Progress 09/01/22 to 08/31/23
Outputs
Target Audience:The fresh and fresh-cut produce industry (growers, processors, and equipment manufacturers), US government agencies, and the scientific community are our primary audience. Given the emergent food safety problems associated with the rapidly evolving controlled environment agriculture (CEA) sector, we have expanded our research, technical support, and outreach efforts to CEA farmers and the CEA food safety alliance. We have delivered science-based knowledge through our project website, face-to-face meetings, consultations, video conference calls, emails, virtual meetings, and peer-reviewed journal publications. A more detailed description of outreach activities is included in Part V.3. "How have the results been disseminated to communities of interest?" Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The team provided training, mentoring, and hands-on working experience to 2 graduate students and two high school students. We also provided training and career development opportunities to two post-doctoral research associates, and three young professionals with B.S. or M.S. degrees. We encouraged and supported graduate students and post-doctoral associates to attend professional meetings, symposia, and workshops, both in person and virtually during 2023, including those organized by the Center for Produce Safety, International Association for Food Protection, and a CEA workshop. We supported them to interact with stakeholders during both stakeholder visits and by visiting farm and fresh-cut processing facilities. How have the results been disseminated to communities of interest?We have delivered targeted outreach efforts for our intended stakeholders by a variety of means including peer-reviewed publications, meeting presentations, website visits, in-person meetings, phone calls, emails, service on the produce industry food safety council, etc. We have translated our scientific findings into recommendations and supported the industry in developing science and risk-based food safety practices. Project team members organized and hosted a two-day food safety workshop attended by more than 50 stakeholders, regulatory partners and food safety research and extension professionals. We also organized another stakeholder meeting to discuss project directions with our industry partners. We shared our food safety research results with FDA scientists and consumer safety officers. We engaged and empowered the national and international scientific community through meeting presentations and publication sharing. We published eight peer-reviewed journal articles and delivered nine oral/poster presentations. We provided education and training to undergraduate and graduate students, and post-doctoral research associates. To increase the visibility of the completed research and the utilization of our research findings, all of our publications are posted on our website for stakeholders and the general public to access and freely download. We also hosted stakeholder visits including an FDA delegation, food safety personnel from Taylor Farms, SmartWashSolutions, and the International Fresh Produce Association, and maintained active communication with the CEA Alliance, and Center for Produce Safety. What do you plan to do during the next reporting period to accomplish the goals?Objectives 1 and 2. We will contiue to develop and optimize our patented in-flight sashing system for improved pathogen reductrion efficicay and early removal of orgniac load. We will expand our study to address the food safety challenges and opportunities in the CEA industry. These include the micorbiome studies on pacakged "ready-to-eat" leafy greens from CEA system, and the potential of blue light for pathogen inactiation and increase in the natural resistance to pathogen growth. Objective 3. We will complete the computations of conmsumption of hypochloriote by organic exudate described in Part V.1 (Objective 3), submit the work for publication, and "translate" the results into a form suitable for use by industry practitioners. Objective 4. Research studies have been completed. Outreach activities will continue. Objective 5. We will continue our strong stakeholder outreach to the produce industry, and support technology adoption by end users, as outlined below: Frequently update website content to reflect project activities, publications, news articles, applications, and other relevant information that benefit the produce industry stakehodlers. Host at least one stakeholder workshop. Deliver at least two webinars to industry stakeholders and at least five oral or poster presentations at scientific or industry meetings.
Impacts
What was accomplished under these goals?
Major impactful achievement: CEA represents a climate-smart approach to grow fresh produce with significant social and environmental benefits. However, pathogen contamination during CEA leafy green production has led to foodborne illness outbreaks and recalls that negatively impact public health and consumer confidence in eating fresh leafy greens. At the request of the produce industry, project team members provided strong technical support to the industry in developing science- and risk-based food safety standards for the industry. We shared our research findings and technical expertise in a broad range of food-safety critical CEA operations, especially in the areas of water management and disinfection during hydroponic growth. Our efforts supported the timely development and launch of the first Commodity Specific Food Safety Guidelines for Controlled Environment Agriculture Focused on Leafy Greens and Herbs. Adoption of this food safety standard will improve industry-wide food safety practices and public health, and support climate-smart agriculture and resilient food systems. Objectives 1 & 2 Baby spinach is nutrient-rich and in high demand by consumers owing to its convenience and freshness. However, contamination with foodborne human pathogens has led to public health concerns. In collaboration with scientists from Israel and Harvard University, the project team evaluated a novel antimicrobial formulation for pathogen reduction, consisting solely of food grade materials. We showed that our combination of gallic acid, hydrogen peroxide, and lactic acid significantly reduced the survival of pathogenic E.coli O157:H7, Listeria monocytogenes, and Salmonella spp. on spinach leaves, while maintaining quality and shelf life of the treated produce. This technology can be the much needed alternative to chlorine as sanitizer for fresh produce washing and disinfection operations especially for organic produce, for which application of chlorine is restricted. In collaboration with University of Connecticut, we completed the development of antimicrobial nanocomplexes as a novel antimicrobial washing solution. We developed an innovative strategy to formulate ionic liquid that helps with dispersing the ZnO nanoparticles uniformly in water. The antimicrobial capacity was tested against two strains - Listeria monocytogenes (L. monocytogenes) and Escherichia coli K-12 (E. coli K-12), based on minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and bacteria growth kinetics. The as-prepared nanoparticles exhibited strong antimicrobial activities as compared with commercial ZnO. The antimicrobial capacity was related to the occurrence of cytolysis, disruption of cell walls, and ROS production. In collaboration with personnel at the Georgia Institute of Technology, the USDA-ARS project team investigated the potential synergy effect of sequential application of peroxyacetic acid (PAA) and UV on E. coli reduction in simulated produce wash water with high organic load. We reported that washing with PAA prior to UV exposure significantly increased UV efficacy on E.coli reduction in wash water with high organic matter. PAA pre-treatment also allowed for reduction of UV treatment time, with concomitant reduction in energy consumption. Objective 3 We are completing computations of the rate at which hypochlorite ion is consumed by chemical reaction with organic exudate during leafy green washing at 4 ºC, using sodium hypochlorite with sodium gluconate (typical of the six-carbon uronic acids, a class of sugar acids that compose 55% and 75% of the nonstarch polysaccharides in cabbage and Iceberg lettuce, respectively). The work uses a realistic bimolecular rate constant, which we obtained by Arrhenius extrapolation of the bimolecular rate recently measured by Prof. C.-H. Huang and Dr. T. Zhang of Georgia Tech at two higher temperatures. Following the end of the no-cost extension, Dr. Dahhea (Hannah) Min, the postdoc performing the computations, temporarily relocated to Utah, and now has a permanent position in Texas. These relocations delayed the computations, which are now back on track. The results to date allow us to compute a) the rate of consumption of hypochlorite, b) the rate of formation of chlorinated byproducts, and c) the extent to which organic exudate inhibits convective transport to the produce surface. The results for all three of these measures clearly demonstrate the importance of removing exudate before application of hypochlorite. These results will be "translated" into terms understandable to industry practitioners, and will inform decisions about "washing before sanitization". This has the potential to reduce formation of chlorinated by-products, chlorine consumption, and contact times, and to improve sanitizer penetration to produce surfaces. Objective 4. All of the research studies in this objective have been previously completed. There is nothing new to report for this objective. Objective 5. Please see "How have the results been disseminated to communities of interest?" section for detailed outreach activities for this project.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Luo, Y. Opportunities for improving food quality and safety of leafy greens in controlled environment agriculture. 2023. Canadian Greenhouse Conference. October 4-5, 2023. Niagara Falls, Canada.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Luo, Y., 2023. Lighting modulation for targeted enhancement in food quality, nutrition, and safety of fresh produce. Greenhouse Lighting and Systems Engineering Webinar Series. https://www.youtube.com/watch?v=JucDs233jSA. March, 21, 2023.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2023
Citation:
Luo, Y. 2023. Improving leafy green food safety via LED light modulation. Workshop on advancing controlled environment agriculture on land and in space in the next 20 years. June 27-28, 2023. Toledo, OH.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Yang, Y., Gu, G., Redding, M., Zhou, B., Luo, Y., Millner, P., and Nou, X. 2023. Survival of Salmonella enterica and Listeria monocytogenes in hydroponic pond water as affected by water microbiota. International Association for Food Protection Annual Meeting. July 16-19, 2023. P2-134.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Gu, G., Zhou, B., Redding, M., Luo, Y., Millner, P. and Nou, X. 2023. Salmonella contamination and microbial dynamics of diced tomatoes during washing and storage as affected by sanitation treatments. International Association for Food Protection Annual Meeting. July 16-19, 2023. P3-199.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Li, Y., Zhou, B., Teng, Z., Zhang, M., Yu, L., Luo, Y., Chen, P. and Sun, J. 2023. Improved metabolomic approach for evaluation of phytochemicals in mustard, kale, and broccoli microgreens under different controlled environmental agriculture conditions. Journal of Agriculture and Food Research. 14: 100719. https://doi.org/10.1016/j.jafr.2023.100719.
- Type:
Journal Articles
Status:
Published
Year Published:
2024
Citation:
Peng, H., Luo, Y., Teng, Z., Zhou, B., Pearlstein, D., Wang, D., Turner, E., Nou, X., Wang, T., Tao, Y., Fonseca, J., and Simko, I. 2024. Genome-wide association mapping reveals loci for oxidative discoloration of cut lettuce. Postharv. Bio. Technol. 112577. https://doi.org/10.1016/j.postharvbio.2023.112577.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Qu, B., Xiao, Z., Luo, Y., and Luo, Y. 2023. Carboxymethyl cellulose capped zinc oxide nanoparticles dispersed in ionic liquid and its antimicrobial effects against foodborne pathogens. Carbohydrate Polymer Technologies and Applications. 6: 100364.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Bolten, S., Mowery, J., Gu, G., Redding, M., Kroft, B., Luo, Y., and Nou, X. 2023. Listeria monocytogenes loss of cultivability on carrot is associated with the formation of mesosome-like structures. Int. J. Food Microbiol. 390: 110121. https://doi.org/10.1016/j.ijfoodmicro.2023.110121.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Gu, G., Zhou, B., Mendes-Oliveira, G., Redding, M., Luo, Y., Millner, P., and Nou, X. 2023. Impact of sanitizer application on Salmonella mitigation and microbiome shift on diced tomato during washing and storage. Postharv. Bio. Technol. 198: 112268. https://doi.org/10.1016/j.postharvbio.2023.112268.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Redding, M., Bolten, S., Gu, G., Luo, Y., Micallef, S. A., Millner, P., & Nou, X. 2023. Growth and inactivation of Listeria monocytogenes in sterile extracts of fruits and vegetables: Impact of the intrinsic factors pH, sugar and organic acid content. Int. J. Food Microbiology. 386: 110043. https://doi.org/10.1016/j.ijfoodmicro.2022.110043
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Wang, D., Zhang. B., Xu, Y., Luo, Y., and Yu, H. 2023. SQ-Swin: a pretrained Siamese quadratic swin transformer for lettuce browning prediction. IEEE Access. 10.1109/ACCESS.2023.3332488
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Zhou, B., Luo, Y., Nou, X., Mwangi, E.., Poverenov, E., Rodov, V., Demokritou, P., and Fonseca, J. M. 2023. Effects of a novel combination of gallic acid, hydrogen peroxide and lactic acid on pathogen inactivation and shelf-life of baby spinach. Food Control. 143: 109284. https://doi.org/10.1016/j.foodcont.2022.109284
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Ding, Q., Gu, G., Luo, Y., Nou, X. and Micallef, S. 2023. Comparison of the recovery efficiency of epiphytically associated Escherichia coli O157:H7 on lettuce plants using different sample preparation methods. International Association for Food Protection Annual Meeting. July 16-19, 2023. P2-182
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Ding, Q., Gu, G., Luo, Y., Nou, X. and Micallef, S. 2023. Comparing Escherichia coli O157:H7 cell count recovery from inoculated store-bought lettuce using sonication or stomaching. 2023. International Association for Food Protection Annual Meeting. July 16-19, 2023. P2-183
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Gu, G., Redding, M., Yang, Y., Ding, Q., Gu, T., Zhou., Luo, Y., Micallef, S., Zhang, B., and Nou, X. 2023. Evaluation of romaine lettuce quality and microbial ecology under source processing and forward processing conditions. International Association for Food Protection Annual Meeting. July 16-19, 2023. P3-198.
|
Progress 09/01/21 to 08/31/22
Outputs
Target Audience:The fresh and fresh-cut produce industry (growers, processors, and equipment manufacturers), supply chain associations/coalitions, grocery stores, US government agencies, and the scientific community are our primary audience. In this past year, our research and outreach have also benefited importers, distributors, consumers, and the general public. With rapid growth of urban and controlled environment (indoor) agriculture (CEA) and its associated food safety risk profile, we have expanded our outreach efforts to this new sector. We have delivered science-based knowledge through our project website, on-demand videos, face-to-face meetings, consultations, video conference calls, emails, virtual meetings and workshops, and peer-reviewed journal publications. A more detailed description of outreach activities is included in Part V.3. "How have the results been disseminated to communities of interest?" Changes/Problems:Received no cost extension for two years due to travel and facility access challenges caused by the COVID-19 pandemic. What opportunities for training and professional development has the project provided?The team provided training, mentoring, and hands-on working experience to 4 undergraduate students, 2 Ph.D. students, and two high school students. We also provided training and career development opportunities to 3 post-doctoral research associates. We encouraged and supported graduate students and post-doctoral associates to attend professional meetings, symposia, and workshops, both in person and virtually during 2022, including those organized by the Center for Produce Safety, International Association for Food Protection, and a NASA-supported Food Safety Workshop. We also encouraged them to visit farms and fresh-cut processors and interact with stakeholders. ? How have the results been disseminated to communities of interest?We have delivered targeted outreach efforts for our intended stakeholders by a variety of means including peer-reviewed publications, meeting presentations, website visits, in-person meetings, phone calls, emails, service on the produce industry food safety council, etc. We briefed and maintained close partnerships with the fresh produce industry regarding the USDA's food safety research programs and capacities, promoting stakeholders' improved understanding, appreciation, and support of food safety research. We maintained active communication and interaction with the FDA through both formal and informal methods, including meeting presentations, co-authored publications, emails, phone calls, and in person visits. We engaged and empowered the national and international scientific community through meeting presentations and publication sharing. Team members presented oral and poster presentations at multiple scientific meetings including those organized by the International Association for Food Protection, Institute of Food Technologists, and Center for Produce Safety. We published 13 peer-reviewed journal articles and delivered 5 oral/poster presentations. We provided education and training to undergraduate and graduate students, and post-doctoral research associates. To increase the visibility of the completed research and the utilization of our research findings, all of our publications are posted on our website for stakeholders and the general public to access and freely download. Project team members also provided invited workshop talks and timely technical consultation to NASA scientists regarding food safety risks associated with leafy vegetables grown in controlled environment agriculture. What do you plan to do during the next reporting period to accomplish the goals?The majority of the laboratory-based studies have been completed, but the large pilot-plant trials, as well as commerical trials with our industry partners, have been delayed by the COVID-19 pandemic. Thus, these research trials will be our main focus for this coming reporting period when conditions permit. Specifically, we will work with McEntire Produce to evaluate a novel technology (single-pass washing) to reduce pathogen cross-contamiantion during fresh-cut washing processes, and with Taylor Farms/SmartWashSolutions to optimize the technology to accelerate pathogen die-off during storage while maintaining product quality and shelf life. We will continue trials to test modifications to and validation of our In-Flight Washing system with a variety of produce commodities. In addition, we will work with our team members at UIUC and MIT to utilize new foundational knowledge gained from their fluid dynamic and mechanistic studies to optimize produce wash system design and operation to enhance food safety and process efficiency. Objective 3. We will complete our work on computation of the reaction of sodium hypochlorite with the salt of a typical uronic acid (sodium gluconate). These computations are needed to predict the rate at which hypochlorite ion is consumed by this reaction, and the rate of chlorinated by-product formation. These computations have benefited tremendously from measurements of the bimolecular rate constant for reaction of sodium hypochlorite with sodium gluconate, performed under the direction of Prof. Ching-Hua Huang at the Georgia Institute of Technology. We anticipate an active collaboration with Prof. Huang and her group. We are working with the USDA-ARS team to "translate" the computational results of our work into a form that would be accessible to the produce washing community. This will involve "converting" the dimensionless time, dimensionless position, Reynolds number, and dimensionless concentration to dimensional time, position, velocity, and concentration, and describing how washout times depend on velocity. Objective 4. Research studies have been completed. Outreach activities will continue. Objective 5. We will continue our strong stakeholder outreach to the produce industry and support technology adoption by end users, as outlined below: Publish at least ten research articles in peer-reviewed or trade journals featuring research findings. Frequently update website content to reflect project activities, publications, news articles, applications, and other relevant inforamtion that benefit the produce industry stakehodlers. Host at least one stakeholder workshop in conjunction with either an industry food safety meetings (e.g., Center for Produce Safety Symposium) or scientific meeting. Deliver at least two webinars to industry stakeholders and at least ten oral or poster presentations at scientific or industry meetings.
Impacts
What was accomplished under these goals?
One of our research articles, entitled "Guidelines to Validate Control of Cross-Contamination during Washing of Fresh-Cut Leafy Vegetables" has been widely cited by the research community. This article received the First Place Most-cited Publication Award conferred by the International Association for Food Protection. Findings have been widely used by the industry and the FDA to develop science- and risk-based food safety practices for fresh-cut processing. Objectives 1 & 2 Multiple salmonellosis outbreaks in recent years have been associated with consumption of contaminated whole and diced tomatoes. ARS scientists evaluated the impact of commonly used and novel sanitizers on the mitigation of Salmonella and shifts in indigenous microbiota on diced tomatoes after washing and during storage. Results indicated that application of a new sanitizer blend containing peracetic acid, sulfuric acid, and a surfactant in washing significantly reduced the survival of inoculated Salmonella on diced tomato and the occurrence of Salmonella cross-contamination of uninoculated samples. Findings from this research suggest that use of the new blend in diced tomato washing could improve the efficacy of Salmonella reduction and cross-contamination prevention, and could extend the product shelf life by suppressing growth of major spoilage bacteria. Carrot is an agricultural commodity that shows antimicrobial activity against foodborne pathogen Listeria monocytogenes (Lm) but the underlying mechanism of action is not well known. ARS scientists examined carrot anti-listerial activity and determined that several Listeria species are equally susceptible to exposure to fresh-cut carrots. On cut carrot surfaces, Lm seemed to quickly lose the ability to grow, although cell membranes remained intact. This loss of cultivability is associated with formation of mesosome-like structures in Lm. This finding is useful in better understanding carrot anti-listerial activity and the survival of Listeria in fresh produce. In recent years Listeria monocytogenes (Lm) outbreaks and recalls associated with fresh produce have heightened concerns and demands from industry. However, little is known about the interactions between Lm and the indigenous microbiota on fresh produce during storage. In this research, ARS scientists examined the dynamics of Lm inoculum and indigenous bacteria on fresh produce during storage at refrigerated and abusive temperatures. The initial indigenous microbial populations on whole avocado, fresh-cut cantaloupe, and romaine lettuce were about 5 log CFU/fruit, 2 log CFU/g, and 5 log CFU/g, respectively. After storage, inoculated Lm populations decreased on the surface of avocado but increased on fresh-cut cantaloupe and romaine lettuce. Fresh-cut cantaloupe provided favorable growth conditions for Lm proliferation (1.7 and > 6 log increase at refrigerated and abusive temperatures, respectively) to overtake indigenous bacteria. The growth rate of Lm on fresh-cut lettuce was lower than that of the total mesophilic bacteria, resulting in 0.4 and > 2 log increase at refrigerated and abusive temperatures, respectively. Microbial diversity analyses indicated Lm growth might be associated with fresh produce microbiota. The highest microbial diversity was found on whole avocado, followed by fresh-cut romaine lettuce, with fresh-cut cantaloupe displaying the least diversity. Data derived from this study could contribute to better understanding the relationship between Lm and indigenous microbiota on fresh produce during storage. Research team collaborated with University of Connecticut in developing antimicrobial nocomplexes comprising of chemically-modified natural biopolymers and plant-based antimicrobial phytochemicals. These nanocomplexes showed strong antibacterial efficacy against foodborne human pathogens, including Listeria monocytogenes and Salmonella Enteritidis. The teams are currently working on further optimization of product preparation for potentially scale-up tests for leafy greens and canloupes. Objective 3 Following development of a computational model to calculate the rate at which hypochlorite ion is consumed by chemical reaction with organic exudate during leafy green washing, we are now completing detailed computations for the 4 ºC reaction of sodium hypochlorite with sodium gluconate using a realistic bimolecular rate constant.(The rate constant is obtained by Arrhenius extrapolation of the bimolecular rate recently measured by Prof. C.-H. Huang and Dr. T. Zhang of Georgia Tech at two higher temperatures.)Sodium gluconate is the sodium salt of gluconic acid, a typical six-carbon uronic acid, a class of sugar acids that compose 55% and 75% of the nonstarch polysaccharides in cabbage and Iceberg lettuce, respectively.This model has allowed us to compute a) the rate of consumption of hypochlorite, b) the rate of formation of chlorinated by-products, and c) the extent to which organic exudate inhibits convective transport to the produce surface. The results for all three of these measures clearly demonstrate the importance of removing exudate before application of hypochlorite. These results will be "translated" into terms understandable to industry practitioners, and will inform decisions about "washing before sanitization". This has the potential to reduce formation of chlorinated by-products, chlorine consumption, and contact times, and to improve sanitizer penetration to produce surfaces. Objective 4. All of the research studies in this objective have been previously completed. There is nothing new to report for this objective. Objective 5. Please see "How have the results been disseminated to communities of interest?" section for detailed outreach activities for this project.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Bertoldi, B., Bardsley, C.A., Pabst, C.R., Baker, C.A., Gutierrez, A., De, J., Luo, Y., and Schneider, K.R. 2022. Influence of free chlorine and contact time on the reduction of Salmonella cross-contamination of tomatoes in a model flume system. Food Protection. 85(1):2226. https://doi.org/10.4315/JFP-21-212.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Cohen, Y., Mwangi, E., Tish, N., Xu, J., Vaze, N.D., Klingbell, T., Fallik, E., Luo, Y., Demokritou, P., Rodov, V., and Poverenov, E. 2022. Quaternized chitosan as a biopolymer sanitizer for leafy vegetables: synthesis, characteristics, and traditional vs. dry nano-aerosol applications. Food Chemistry. 378. Article 132056. https://doi.org/10.1016/j.foodchem.2022.132056.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Gu, G., Kroft, B., Lichtenwald, M., Luo, Y., Millner, P., Patel, J., and Nou, X. 2022. Dynamics of Listeria monocytogenes and the microbiome on fresh-cut cantaloupe and romaine lettuce during storage at refrigerated and abusive temperatures. Int. J. Food Microbiol. 364:109531. https://doi.org/10.1016/j.ijfoodmicro.2022.109531.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Kroft, B., Gu, G., Bolten, S., Micallef, S.A., Luo, Y., Millner, P., and Nou, X. 2022. Effects of temperature abuse on the growth and survival of Listeria monocytogenes on a wide variety of whole and fresh-cut fruits and vegetables during storage. Food Control. 137: 108919. https://doi.org/10.1016/j.foodcont.2022.108919.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Liu, Z., Teng, Z., Pearlstein, D.J., Chen, P., Yu, L., Zhou, B., Luo, Y., Sun, J. 2022. Effects of different light-emitting diode illumination on bioactive compounds in Ruby Streaks mustard microgreens by Ultra-High Performance Liquid Chromatography?High-Resolution Mass Spectrometry. ACS Food Sci. Technol. 2022, 2, 9, 14831494. https://pubs.acs.org/action/showCitFormats?doi=10.1021/acsfoodscitech.2c00193&ref=pdf
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Mendes-Oliveira, G., Gu, G., Luo, Y., Zografos, A., Minas, I., and Nou, X. 2022. Edible and water-soluble corn zein coating impregnated with nisin for Listeria monocytogenes reduction on nectarines and apples. Postharvest Biology and Technology, 185: 111811. https://doi.org/10.1016/j.postharvbio. 111811.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Mendes-Oliveira, G., Luo, Y., Zhou, B., Gu, G., Teng, Z., Bolten, S., Park, E., Pearlstein, D., Turner, E.R., Millner, P.D., and Nou, X. 2022. Use of a silver-based sanitizer to accelerate Escherichia coli die-off on fresh-cut lettuce and maintain produce quality during cold storage: Laboratory and pilot-plant scale tests. Food Res. Int. 157. Article 111170. https://doi.org/10.1016/j.foodres.2022.111170.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Peng, H., Luo, Y., Teng, Z., Zhou, B., Bornhorst, E. R., Fonseca, J. M., and Simko, I. 2021. Phenotypic characterization and inheritance of enzymatic browning on cut surfaces of stems and leaf ribs of romaine lettuce. Postharvest Biol. Technol. 181. Article 111653. https://doi.org/10.1016/j.postharvbio.2021.111653
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Teng, Z., Luo, Y., Pearlstein, D.J., Zhou, B, Johnson, C.M., Mowery, J., Wang, Q., and Fonseca, J. 2022. Agarose hydrogel composite supports microgreen cultivation with enhanced porosity and continuous water supply under terrestrial and microgravitational conditions. International Journal of Biological Macromolecules. 220: 135-146. https://doi.org/10.1016/j.ijbiomac.2022.08.046.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Xue, J., Luo, Y., Li, B., Wang, X., Xiao, Z., and Luo, Y. 2022. Antimicrobial effects of thymol-loaded phytoglycogen/zein nanocomplexes against foodborne pathogens on fresh produce. International Journal of Biological Macromolecules. 209A:1188-1196. https://doi.org/10.1016/j.ijbiomac.2022.04.101.
- Type:
Journal Articles
Status:
Published
Year Published:
2022
Citation:
Zhang, T., Luo, Y., Zhou, B., Teng, Z, and Huang, C.H. 2022. Sequential application of peracetic acid and UV irradiation (PAA-UV/PAA) for improved bacterial inactivation in fresh-cut produce wash water. ACS EST Water. 2(7): 12471253. https://doi.org/10.1021/acsestwater.2c00087
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Lu, Y., Dong, W., Yang, T., Luo, Y., Chen, P. 2021. Preharvest UVB application increases glucosinolate contents and enhances postharvest quality of broccoli microgreens. Molecules. 26 (11):3247. doi: 10.3390/molecules26113247.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Liu, Z., Sun, J., Teng, Z., Luo, Y., Yu, L., Simko, I., and Chen, P. 2021. Identification of marker compounds for predicting browning of fresh-cut lettuce using untargeted UHPLC-HRMS metabolomics. Postharvest Biol. Technol. 180:111626. https://doi.org/10.1016/j.postharvbio.2021.111626.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Peng, H., Luo, Y., Teng, Z., Zhou, B., Bornhorst, E. R., Fonseca, J. M., and Simko, I. 2021. Phenotypic characterization and inheritance of enzymatic browning on cut surfaces of stems and leaf ribs of romaine lettuce. Postharvest Biol. Technol. 181. Article 111653. https://doi.org/10.1016/j.postharvbio.2021.111653.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Gu, G., Zhen, J., Lichtenwald, M., Zhou, B., Zhang, B., Luo, Y., and Nou, X. (2022). Listeria monocytogenes biofilm formation on coated and non-coated stainless-steel coupons in lettuce juice as affected by environmental microbes. IAFP annual meeting. P1-92, Jul. 31 - Aug. 3, 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Gu, G., Lichtenwald, M., Luo, Y., Millner, P.D., and Nou, X. (2022). Shift in Listeria monocytogenes and microbiome on whole avocado, fresh-cut cantaloupe and romaine lettuce during storage at refrigerated and abused temperatures. IAFP annual meeting. P1-93, Jul. 31 - Aug. 3, 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Niemira, B., Luo, Y., and Goodridge, L. (2022). Safety of fresh produce during space farming: standards and recommendations. NASA Food Safety Workshop.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Luo, Y. (2022) Ensuring food safety of in-flight vegetable production ? microgreens as a model product. Phase 2 Safety Workshop, Deep Space Food Challenge, Apr. 5, 2022
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Zhou, B., Luo, Y., Pearlstein, D.J., Millner, P.D., and Pearlstein, A.J. (2022). A new approach to washing fresh-cut leafy produce. Gordon Research Conference on Fluids in Disease Transmission and Contamination, South Hadley, Mass., Aug. 14-19, 2022.
|
Progress 09/01/20 to 08/31/21
Outputs
Target Audience:The fresh and fresh-cut produce industry (growers, processors, and equipment manufacturers), supply chain associations/coalitions, grocery stores, US government agencies, and the scientific community are our primary audience. In this past year, our research and outreach have also benefited importers, distributors, consumers, and the general public. With rapid growth of the urban and controlled environment (indoor) agriculture (CEA) and the associated new food safety risk profile, we have expanded our outreach efforts to this new sector. We have delivered science-based knowledge through our project website, on-demand videos, face-to-face meetings, consultations, video conference calls, emails, virtual meetings and workshops, and peer-reviewed journal publications. A more detailed description of outreach activities is included in Part V.3. "How have the results been disseminated to communities of interest?" Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The team provided training, mentoring, and hands-on working experience to 3 undergraduate students, and 3 Ph.D. students. We also provided training and career development opportunities to 6 post-doctoral research associates. We encouraged and supported graduate students and post-doctoral associates to attend professional meetings, symposia, and workshops, virtually during 2021, including those organized by the Center for Produce Safety, UC Davis Fresh-cut Workshop, International Association for Food Protection, American Society for Horticultural Science, and the American Physical Society Division of Fluid Dynamics. How have the results been disseminated to communities of interest?We have delivered targeted outreach efforts for our intended stakeholders by a variety of means including peer-reviewed publications, meeting presentations, website visits, in-person meetings, phone calls, emails, service on the produce industry food safety council, etc. We teamed up with Taylor Farms and SmartWashSolutions in developing an industry-oriented food safety workshop entitled "No Silver Bullet in Sight: How to Achieve Continuous Improvement in Fresh Produce Safety with Existing Knowledge and Tools". This workshop was hosted in conjunction with the International Association for Food Protection Annual Meeting and drew a significant number of industry attendees and media attention. Numerous food safety news and press organizations including Food Safety News further reported on it and helped us to broadcast the message. We maintained close partnership with the industry and provided data and consultation in support of their effort to implement food safety best practices for imported papayas. Given the source of the pathogen contamination for papayas, we also reached out to Mexican scientists and shared our research findings and recommendations. We maintained active communication and interaction with the FDA through both formal and informal methods, including meeting presentations, co-authored publications, emails, phone calls, and in person visits. We engaged and empowered the national and international scientific community through meeting presentations and publication sharing. Team members presented oral and poster presentations at multiple scientific meetings including those organized by the International Association for Food Protection, American Society for Horticultural Sciences, Institute of Food Technologists, and Center for Produce Safety. We published 25 peer-reviewed journal articles and delivered 8 oral and poster presentations. We provided education and training to undergraduate and graduate students, and post-doctoral research associates. To increase the visibility of the completed research and the utilization of our research findings, all of our publications are posted on our website for stakeholders and the general public to access and free download. The https://www.producefoodsafety.org website received 1600 unique visits and 2640 views from September 1, 2020 through August 30, 2021, with 90 downloads. What do you plan to do during the next reporting period to accomplish the goals? Objectives 1 and 2. The majority of the laboratory-based studies have been completed, but the large pilot-plant trials, as well as commerical trials with our industry partners, have been delayed by the COVID-19 pandemic. Thus, these research trials will be our main focus for this coming reporting period when conditions permit. Specifically, we will work with McEntire Produce to evaluate a novel technology (single pass) to reduce pathogen cross-contamiantion during fresh-cut wash process, and with Taylor Farms/SmartWashSolutions to optimize the technology to accelerate pathogen die-off during storage while maintaining product quality and shelf life. We will continue trials to test modifications to and validation of our In-Flight Washing system with a variety of produce commodities. In addition, we will work with our team members in UIUC and MIT to utilize new foundational knowledge gained from their fluid dynamic and mechanistic studies to optimize produce wash system design and operation to enhance food safety and process efficiency. Objective 3. We will complete our work on computation of the reaction of sodium hypochlorite with the salt of a typical uronic acid (sodium gluconate). These computations are needed to predict the rate at which hypochlorite ion is consumed by this reaction, and the rate of chlorinated by-product formation. These computations have benefited tremendously from measurements of the bimolecular rate constant for reaction of sodium hypochlorite with sodium gluconate, performed under the direction of Prof. Ching-Hua Huang at the Georgia Institute of Technology. We anticipate an active collaboration with Prof. Huang and her group. We are working with the USDA-ARS team to "translate" the computational results of our work into a form that would be accessible to the produce washing community. This will involve "converting" the dimensionless time, dimensionless position, Reynolds number, and dimensionless concentration to dimensional time, position, velocity, and concentration, and describing how washout times depend on velocity. Objective 4. Research studies have been completed. Outreach activities will continue. Objective 5. We will continue our strong stakeholder outreach to the produce industry and support the technology adoption by the end users, as outlined below: Publish at least eight research articles in peer-reviewed or trade journals featuring research findings. Frequently update website content to reflect project activities, publications, news articles, applications, and other relevant inforamtion that benefit the produce industry stakehodlers. Host at least two stakeholder workshops in conjunction with either the industry food safety meetings (e.g. Center for Produce Safety Symposium) or the scientific meetings. Deliver at least three webinars to industry stakeholders and at least eight oral or poster presentations at scientific or industry meetings.
Impacts
What was accomplished under these goals?
With the pandemic and the related travel and facility access limitations presenting challenges to our pilot plant trials, we pivoted to developing novel antimicrobial technologies and advance the understanding of fundamental science pertaining to produce washing, disinfection, and food safety. Significant accomplishments are outlined below for each objectives. Objectives 1 & 2 We investigated microbiome shifts on selected fresh produce and the effects on Listeria monocytogenes survival during storage at "normal" and elevated temperatures, using 16S rDNA sequencing. Fresh-cut cantaloupe, which featured a very simple initial microbiome, supported L. monocytogenes growth to become the dominant microbial component. The outcome of L. monocytogenes growth on fresh-cut romaine lettuce, which has a moderately complex microbiome, was more varied. In contrast, L. monocytogenes failed to grow on avocado surfaces. These observations highlight the important role of background microbiota in determining L. monocytogenes growth. We further isolated and identified multiple anti-listerial bacteria from romaine lettuce, including Lactococcus lactis, Leuconostoc mesenteroides, and Weissella cibaria. One of these isolates exhibited very strong growth inhibition/inactivation against L. monocytogenes when co-inoculated in a liquid medium. These results suggested that modification of the fresh produce microbiome could be a useful tool for controlling the growth of foodborne pathogens such as L. monocytogenes. Sanitation of fresh-cut (diced) tomato is challenging due to the high organic content in wash water. In collaboration with our industry partners, we evaluated the performance of a new sanitizer formulation (CMS, containing peracetic acid, sulfuric acid, and copper) designed for sanitation efficacy against Salmonella cross-contamination and survival during diced tomato washing and storage. Commonly used sanitizers, including chlorine and peracetic acid were also tested for comparison. Salmonella cross-contamination frequency and population were significantly lower on samples washed with sanitized water, especially using the novel sanitizer blend. Significant differences for total mesophilic aerobic bacteria, yeast, and mold were also detected among washing treatments. CMS-washed diced tomato also exhibited improved quality retention after two-week cold storage. These observations support the potential use of CMS as a suitable formulation for cleaning diced tomato. Waxing or coating is an effective commercial practice for a variety of fresh fruit to maintain quality appeal during storage and to extend shelf life. However, wax is difficult to remove from fruit surfaces and has limited effectiveness in reducing or eliminating foodborne pathogen contamination. In collaboration with our industry partners, we evaluated the performance of an edible and water-soluble corn zein coating impregnated with nisin for L. monocytogenes reduction on nectarines and apples. Nisin-impregnated corn zein coating outperformed waxing in preventing survival of L. monocytogenes inoculated in simulation of either pre- or post-coating contamination. Corn zein coating also improved retention of fruit firmness and reduced weight loss. This study demonstrated the strong potential of edible fruit coatings impregnated with a variety of natural anti-microbials as a promising intervention strategy against a wide range of foodborne pathogens. We collaborated with Harvard University to develop biodegradable fibers and nature-derived anti-microbials for smart food packaging with enhanced food safety and quality characteristics. By incorporating nature-derived anti-microbial agents, these fibers possessed strong efficacy against both gram positive (L. innocua) and gram negative (E. coli) pathogen surrogates. We further explored the design and development of "multi-stimuli responsive" fibers for controlled release of anti-microbial agents in response to environmental triggers (e.g., high relative humidity and enzymes). This research has revealed the potential to synthesize fibers for sustainable, "smart" food packaging materials using nature-derived biopolymers and anti-microbials. Free chlorine is an effective disinfectant for produce washing but may lead to formation of harmful disinfection byproducts (DBPs). In collaboration with Georgia Tech, we comprehensively evaluated the formation of DBPs during commercial washing of fresh-cut produce (lettuce and cabbage) using traditional double-flume wash and novel immersion-free single-pass wash systems. Water and produce samples were collected at multiple time points and locations from the processing lines and analyzed. The DBPs investigated included a comprehensive suite of 33 conventional and emerging DBPs, i.e., 4 trihalomethanes (THMs), 9 haloacetic acids (HAAs), 9 nitrogenous DBPs (N-DBPs), and 11 carbonaceous DBPs (C-DBPs). The concentrations of THMs and HAAs on the washed products were further used to estimate potential exposure via consumption of fresh-cut produce. The findings of this study broaden the understanding of the formation and removal of DBPs during wash processes, and identify additional areas for further reduction in DBPs and food safety improvement. Objective 3 Following development of a computational model to calculate the chemical reaction between organic exudate and hypochlorite during leafy green washing, we are now performing detailed computations for the 4 ºC reaction of sodium hypochlorite with sodium gluconate using a realistic bimolecular rate constant. (The rate constant is obtained by Arrhenius extrapolation of the bimolecular rate recently measured by Prof. C.-H. Huang and Dr. T. Zhang of Georgia Tech at two higher temperatures. Previously, we used an arbitrary numerical value for the rate constant, in order to develop the code.) Sodium gluconate is the sodium salt of gluconic acid, a typical six-carbon uronic acid, a class of sugar acids that compose 55% and 75% of the nonstarch polysaccharides in cabbage and Iceberg lettuce, respectively. This model has allowed us to compute a) the rate of consumption of hypochlorite, b) the rate of formation of chlorinated by-products, and c) the extent to which organic exudates inhibit convective transport to the produce surface. The results for all three of these measures clearly demonstrate the importance of removing exudate before application of hypochlorite. These results will be "translated" into terms understandable to industry practitioners, and will inform decisions about "washing before sanitization". This has the potential to reduce formation of chlorinated by-products, chlorine consumption, and contact times, and to improve sanitizer penetration to produce surfaces. Objective 4. All of the research studies in this objective have been previously completed. There is nothing new to report for this objective. Objective 5. Please see "How have the results been disseminated to communities of interest?" section for detailed outreach activities for this project.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Aytac, Z., Xua, J., Pillai, S.K.R., Eitzer, B.D, Xu, T., Vaze, N., Ng, K.W., White, J.C., Chan-Park, M.B., Luo, Y., and Demokritou, P. 2021. Enzyme- and relative humidity-responsive antimicrobial fibers as active food packaging. ACS Appl. Mater. Interfaces. 13: 5029850308. https://doi.org/10.1021/acsami.1c12319
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Bertoldi, B., Bardsley, C.A., Pabst, C.R., Baker, C.A., Gutierrez, A., De, J., Luo, Y. and Schneider, K.R. 2021. The influence of organic load and free chlorine on Salmonella cross-contamination of tomatoes in a model flume system. J. Food Prot. in press, http://doi: 10.4315/JFP-21-212.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Bertoldi, B., Bardsley, C.A, Baker, C.A., Pabst, C.R, Gutierrez, A., De, Jaysankar, Luo, Y., and Schneider, K.R. 2021. Determining bacterial load and water quality parameters of chlorinated tomato flume tanks in Florida packinghouses. J. Food Prot. 84: 17841792. https://doi.org/10.4315/JFP-21-100
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Bolten, S., Gu, G., Luo, Y., Haute, S. V., Zhou, B., Millner, P. D., Micallef, S. A., and Nou, X. 2020. Salmonella inactivation and cross-contamination on cherry and grape tomatoes under simulated wash conditions. Food Microbiol. 87: 103359. https://doi.org/10.1016/j.fm.2019.103359.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Bolten, S., Gu, G., Luo, Y., Haute, S.V., Zhou, B., Millner, P.D., Micallef, S.A., and Nou, X. 2020. Salmonella inactivation and cross-contamination on cherry and grape tomatoes during washing under simulated wash conditions. Food Microbiol. 87:103359. https://doi.org/10.1016/j.fm.2019.103359.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Chen, C.-H, Yin, H.-B., Teng, Z., Byun, S., Guang, Y., Luo, Y., Upadhyay, A., and Patel, J. 2021. Nanoemulsified carvacrol as a novel washing treatment reduces Escherichia coli O157:H7 on spinach and lettuce. J. Food Prot. 84: 2163-2173. https://doi.org/ 10.4315/JFP-21-151
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Gu, G., Bolten, S., Mendes-Oliveira, G., Zhou, B., Teng, Z., Pearlstein, D., Luo, Y., Millner, P. D., and Nou, X. 2021. Salmonella inactivation and sponge/microfiber mediated cross-contamination during papaya wash with chlorine or peracetic acid as sanitizer. Food Microbiol. 95:103677. https://doi.org/10.1016/j.fm.2020.103677.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Gu, T., Meesrisom, A., Luo, Y., Dinh, Q.N., Lin, S., Yang, M., Sharma, A., Tang, R., Zhang, J., Jia, Z., Millner, P.D., Pearlstein, A.J., and Zhang, B. 2021. Listeria monocytogenes biofilm formation as affected by stainless steel surface topography and coating composition. Food Control. 130, 198275. https://doi.org/10.1016/j.foodcont.2021.108275
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Huang, R., Vaze, N., Soorneedi, A., Moore, M. D., Luo, Y., Poverenov, E., Rodov, V., and Demokritou, P. 2021. A novel antimicrobial technology to enhance food safety and quality of leafy vegetables using engineered water nanostructures. Environ. Sci.: Nano, 8(2): 514-526. https://doi.org/10.1039/D0EN00814A.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Jia, Z., Luo, Y., Wang, D., Dinh, Q. N., Lin, S., Sharma, A., Block, E. M., Yang, M., Gu, T., Pearlstein, A. J., Yu, H., and Zhang, B. 2021. Nondestructive multiplex detection of foodborne pathogens with background microflora and symbiosis using a paper chromogenic array and advanced neural network. Biosens. Bioelectron. 183: 113209. https://doi.org/10.1016/j.bios.2021.113209.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Ma, P., Zhang, J., Teng, Z., Zhang, Y., Bauchan, G.R., Luo, Y., Liu, D., and Wang. Q. 2021. Metalorganic framework-stabilized high internal phase pickering emulsions based on computer simulation for curcumin encapsulation: comprehensive characterization and stability mechanism. ACS Omega. 6 (40): 26556-26565
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Mei, L., M., Zhang, F., Zhang, J., Li, Y., Liu, Y., Luo, Y., and Wang, Q. 2021. Alkynyl silver modified chitosan and its potential applications in food area. Carbohydr. Polym. 254:117416. https://doi.org/10.1016/j.carbpol.2020.117416.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Nong, W., Guan, W., Yang, Y., Lu, C., Wang, Q., Luo, Y., Zhang, B., Xu, Z., Wu, J., and Guan, Y. 2021. Photo-triggered on-demand carvacrol vapor release from nano-generators for non-contact bacterial inactivation between nanomaterials and bacteria. Chem. Eng. J. 420:129874. https://doi.org/10.1016/j.cej.2021.129874
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Tan, J., Zhou, B., Luo, Y, and M.V. Karwe. 2021. Numerical simulation and experimental validation of bacterial detachment using a spherical produce model in an industrial-scale flume washer. Food Control. 130: 108300. https://doi.org/10.1016/j.foodcont.2021.108300
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Teng, Z., Luo, Y., Zhou, B., Wang, Q., and Hapeman, C.J. 2021. Characterization and mitigation of chemical oxygen demand and chlorine demand from fresh produce wash water. Food Control. 127: 108112. https://doi.org/10.1016/j.foodcont.2021.108112
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Wang, T., Wusigale, D.K., Amalaradjou, M.A., Luo, Y., and Luo, Y. 2021. Polydopamine-coated chitosan hydrogel beads for synthesis and immobilization of silver nanoparticles to simultaneously enhance antimicrobial activity and adsorption kinetics. Adv. Composites Hybrid Mater. 4, 696-706 (2021). https://doi.org/10.1007/s42114-021-00305-1
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Xue, J., Luo, Y., Balasubramanian, B., Upadhyay, A., Li, Z., and Luo, Y. 2021. Development of novel biopolymer-based dendritic nanocomplexes for encapsulation of phenolic bioactive compounds: A proof-of-concept study. Food Hydrocolloids. 120: 106987. https://doi.org/10.1016/j.foodhyd.2021.106987.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Yang, M., Liu, X., Luo, Y., Pearlstein, A. J., Wang, S., Dillow, H., Reed, K., Jia, Z., Sharma, A., Zhou, B., Pearlstein, D., Yu, H., and Zhang, B. 2021. Machine learning-enabled non-destructive paper chromogenic array detection of multiplexed viable pathogens on food. Nature Food. 2: 110-117. https://doi.org/10.1038/s43016-021-00229-5
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Zhang, T., Lee, W., Luo, Y., and Huang, C. 2022. Flume and single-pass washing systems for fresh-cut produce processing: Disinfection by-products evaluation. Food Control. 133, Part A: 108578. https://doi.org/10.1016/j.foodcont.2021.108578
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Zhou, B., Luo, Y., Teng, Z., Nou, X., and Millner, P. 2021. Factors impacting chemical and microbiological quality of wash water quality during simulated dump tank wash of grape tomatoes. J. Food Prot. 84: 695-703. https://doi.org/10.4315/JFP-20-343.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Zhou, B., Luo, Y., Huang, L., Fonseca, J.M., Yan, H., and Huang, J. 2021. Determining effects of temperature abuse timing on shelf life of RTE baby spinach through microbial growth models and its association with sensory quality. Food Control. 133, Part B: 108639. https://doi.org/10.1016/j.foodcont.2021.108639
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Zhou, B., Luo, Y., Huang, L., Fonseca, J. M., Yan, H., and Huang, J. 2022. Determining effects of temperature abuse timing on shelf life of RTE baby spinach through microbial growth models and its association with sensory quality. Food Control. 133: 108639. https://doi.org/10.1016/j.foodcont.2021.108639.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Bertoldi, B, Pabst, C.R., Baker, C.A., Gutierrez, A., De J., and Schneider, K.R. 2021. Evaluating the Potential of 25 ppm Sodium Hypochlorite in Preventing Cross-Contamination of Tomatoes in a Laboratory Model Flume. IAFP Annual Meeting, Phoenix, AZ/Virtual. Poster.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Gu, G., Ottesen, A., and Nou, X. 2021. Effect of sanitation on microbiome and relevance of foodborne pathogens during produce production. Institute for Food Safety and Health (IFSH) / Food Research Institute (FRI) Virtual Annual Symposium. September 27-30, 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Gu, G., Lichtenwald, M., Luo, Y., and Nou, N. 2021. Survival of Listeria monocytogenes in romaine lettuce juice and isolation of antilisterial bacteria. P2-124. International Association for Food Protection Annual Meeting. A Virtual Meeting, July 18-21, 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Luo, Y. 2021. Moving the Mountain Together: The Industry, Academia, and Government Partnership is Essential for the Development of Best Practices. International Association for Food Protection Annual Meeting, Phoenix, AZ. July 2021.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2021
Citation:
Luo, Y. 2021. Mexico-USDA. Government-industry partnership in developing solutions to pathogen cross-contamination during packing house operation of tomatoes and papayas . 7th CIAD (Mexico) and ARS Workshop. Feb 2021.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2021
Citation:
Luo, Y. Particulate-mediated pathogen cross-contamination an overlooked food safety risk factor. FDA-ARS meeting. May, 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Mendes-Oliveira, G., Luo, Y., Nou, X. 2021. Ultrasonic formulation of bergamot oil and linalool nanoemulsions and their bactericidal activity. P1-34. International Association for Food Protection Annual Meeting. A Virtual Meeting, July 18-21, 2021.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Mendes-Oliveira, G., Zografos, A., Luo, Y., Nou, X. 2021. Antimicrobial effects of corn zein impregnated with nisin as edible coating for mangoes stored at different temperatures. P1-35. International Association for Food Protection Annual Meeting. A Virtual Meeting, July 18-21, 2021.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Bauyrzhan, P., Pahlavan, A., Bourouiba, L., Bush, J and Juanes, R. 2020. Spin coating of capillary tubes. Journal of Fluid Mechanics. 886:A30
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Wang, Y. and Bourouiba, L. 2021. Growth and breakup of ligaments in unsteady fragmentation. J. Fluid Mech. 910:A39.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Bourouiba, L. 2021. The fluid dynamics of disease transmission. Ann. Rev. Fluid Mech. 53:473-508.
|
Progress 09/01/19 to 08/31/20
Outputs
Target Audience:Our primary target audience is the fresh and fresh-cut produce industry (growers, processors, and equipment manufacturers), supply chain associations/coalitions, grocery stores, US government agencies, and the scientific community. In this past year, our research studies and outreach efforts have also benefited importers, distributors, consumers, and the general public. We also expanded our audience to include growers in the urban agriculture/controlled environment agriculture field. We have delivered science-based knowledge to these groups through a variety of means, including our project website, videos, face-to-face meetings, consultations, video conference calls, emails, virtual meetings and workshops, peer-reviewed journal publications, and agricultural extension fact sheets. More detailed outreach activities are included in Part V.3. How have the results been disseminated to communities of interest?? Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The team provided training, mentoring, and hands-on working experience to 3 undergraduate students, and 4 Ph.D. students, including a minority group Ph.D. student. We also provided training and career development opportunities to 6 post-doctoral research associates, and 1 minority group student intern. We encouraged and supported graduate students and post-doctoral associates to attend professional meetings, symposia, and workshops, virtually during 2020, including those organized by the Institute of Food Technologists, International Association for Food Protection, the Center for Produce Safety, American Society for Horticultural Science, and the American Physical Society Division of Fluid Dynamics. We also facilitated training of postdoc and support staff on this project through the UC Davis fresh-cut virtual workshop. We fostered unique opportunities for students and post-doctoral research associates in engineering and life science to receive interdisciplinary training in food safety, produce processing, and microbiology through collaborative research, seminars, frequent conference calls, and site visits. We provided laboratory and fresh-cut processing pilot plant tours to a several officials from USDA's Foreign Agricultural Service. This provided a unique opportunity for the U.S.'s top agriculture diplomats to learn the challenges and opportunities associated with maintaining quality and safety of fresh produce. We provided a seminar to UMD students, and recruited, and mentored a minority student intern. How have the results been disseminated to communities of interest?We have delivered targeted outreach efforts for our intended stakeholders via peer-reviewed publications and presentations, stakeholder workshops, videos, website visits, face-to-face meetings (pre-pandemic), phone calls, emails, on-site visits, and service on the produce industry food safety council, etc. To support the translation of our research findings into actionable steps, we organized and hosted a virtual international food safety conference and stakeholder workshop on October 1 and 8, 2020. Project team members made 17 oral presentations. A stakeholder advisory board meeting was also held in conjunction with this workshop. Over 150 attendees from the produce and retail industries, regulatory agencies, and scientific communities (including a significant number of HSI and HBCU schools) actively participated in this workshop. Video recordings from this workshop will be made available on our website soon. The project team received highly positive feedback from the stakeholder advisors and workshop participants. In addition, we also maintained and frequently updated our project website https://www.producefoodsafety.org which serves as a major portal for dissemination of information from this project. To increase the visibility of the completed research, the team has linked the resources to other websites such as Colorado State University Food Safety website and the University of Vermont Clearinghouse website for food safety information. Our publications and presentations were shared with the general public, along with our extension publications. The https://www.producefoodsafety.org website received 405 unique visits and 456 views from January 1, 2020 through October 31, 2020, with 1230 downloads. Additional details of our outreach activities for each targeted stakeholder group follow. Produce and retail industries. We continue to engage the fresh and fresh-cut produce industry through service of its members on our stakeholder advisory board (SAB), and have expanded SAB membership to include technical leaders in tomato growing and packing, water treatment, and the emerging field of urban agriculture. Our project team members also serve on the Food Safety and Technology Council of the United Fresh Produce Association (UFPA), the leading industry organization. In addition to working with leafy-green and tomato growers and processors as we have in the past, we targeted outreach to papaya growers and importers this year following an urgent request from UFPA and the Texas International Produce Association for new research studies to support the industry effort to improve food safety of Mexican-grown papaya. We shared our research findings via special presentations to the entire papaya supply chain including papaya growers in Mexico and importers in the US. Our research findings contributed significantly to the development of Food Safety Best Practices for the Growing and Handling of Mexican Papaya. The project team worked closely with major fresh-cut processors (Taylor Farms, SmartWashSolutions, Church Brothers Farms/True Leaf Farms) in our large-scale pilot-plant and shared research findings with them. Subsequently, these research findings also were featured in the California Postharvest Academy, and The Packer newspaper. Additionally, project team members taught several courses during the virtual fresh-cut produce workshop attended by more than 50 industry personnel, and partnered with SmartWashSolutions in developing a symposium proposal for IAFP meeting. Food safety regulators: We maintained active communication and interaction with the FDA through emails, phone calls, meeting presentations, and co-authored publications. We presented our research findings to FDA scientists and policy makers regarding papaya food safety, and shared unpublished data with FDA per request. We also provided technical consultation, publications, and analyses to support FDA food safety risk assessment and modeling tasks. Two FDA personnel also serve on our Stakeholder Advisory Board and have provided guidance on research directions. National and international scientific community. We engaged and empowered the national and international scientific community through meeting presentations and publication sharing. Team members presented oral and poster presentations at multiple scientific meetings including those organized by the International Association for Food Protection, American Society for Horticultural Sciences, Institute of Food Technologists, and Center for Produce Safety. We published 11 peer-reviewed journal articles, secured 1 issued patent, and filed a new patent application. We brought together industry technical personnel, FDA regulatory scientists, and academic researchers. We provided education and training to undergraduate and graduate students, and post-doctoral research associates. Consumers: To provide general information to the consumers about food safety, project team member worked with a USDA-ARS communication specialist to prepare and publish an online news article "Keeping Bagged Leafy Greens Safe and Nutritious for Human Consumption". Research findings on leafy green and tomato food safety from this project were shared with consumers and the general public. https://www.ars.usda.gov/oc/utm/keeping-bagged-leafy-greens-safe-and-nutritious-for-human-consumption/ What do you plan to do during the next reporting period to accomplish the goals? Objectives 1 and 2. The majority of the laborotary-based studies have been completed, but the large pilot plant trials, as well as commerical trials with our industry partners have been delayed by the COVID-19 pandemic. Thus, these research trials will be our main focus for this coming reporting period. Specifically, we will work with McEntire Produce to evaluate a novel technology (single pass) to reduce pathogen cross-contamiantion during fresh-cut wash process, and with Taylor Farm/SmartWashSolutions to optimize the technology to accelerate pathogen die-off during storage while maintaining product quality and shelf life. We will also work with the produce industry to support the implemetnation of our recommended sanitizer concentrations as preventive controls for food safety during fresh-cut produce wash operation. We will continue trials to test modifications to and validation of our In-Flight Washing system with a variety of produce commodities. In addition, we will also work with our team members in UIUC and MIT to utilize new foundational knowledge gained from their fluid dynamic and mechanistic studies to optimize the produce wash system design and operation to enhance food safety and process efficiency. Objective 3. We will complete our computations for the washout of a soluble viscosifying solute (sodium gluconate, a surrogate for the uronic acids comprising over 55% and over 75% of the soluble non-starch polysaccharides in cabbage and iceberg lettuce, respectively. We have performed measurements of the viscosity of aqueous sodium gluconate solutions at 43 combinations of temperature and composition relevant to fresh-cut processing (from 2°C to 25°C). The data below 10°C are the only data for this system). We are preparing a paper for journal submission that critically evaluates and correlates all of the known data. We will continue work on our computations for reaction of sodium hypochlorite with the salt of a typical uronic acid (sodium gluconate). These computations are needed to predict the rate at which hypochlorite ion is consumed by this reaction, and the rate of chlorinated by-product formation. So far, we have used an assumed value for the bimolecular rate constant. These computations will benefit tremendously from measurements of the bimolecular rate constant for reaction of sodium hypochlorite with sodium gluconate, to be performed under the direction of Prof. Ching-Hua Huang at the Georgia Institute of Technology. We anticipate an active collaboration with Prof. Huang and her group. We will work with the USDA-ARS team to "translate" the computational results of our work into a form that would be accessible to the produce washing community. This will involve "converting" the dimensionless time, dimensionless position, Reynolds number, and dimensionless concentration to dimensional time, position, velocity, and concentration, and describing how washout times depend on velocity. Objective 4. Research studies have been completed. Outreach activities will continue. Objective 5. Strong stakeholder outreach will be the primary focus in this reporting period. We intend to translate our research findings as follows: Publish at least ten research articles in peer-reviewed or trade journals featuring research progress relevant to fundamental and applied science/engineering relative to fresh and fresh-cut produce food safety, equipment design, and operational practices. Frequently update website content to reflect project activities, research and extension publications, and practical applications of the research to stakeholder and industry needs. Continue to hold project team and stakeholder advisory board meetings. Continue collaboration with UC Davis Post-harvest Center in delivering annual fresh-cut workshop for industry stakeholders. Host a stakeholder workshop in conjunction with either the Center for Produce Safety Symposium or the United Fresh Produce Public Policy Conference. Deliver at least five webinars to industry stakeholders and at least six oral or poster presentations at scientific meetings.
Impacts
What was accomplished under these goals?
Impact Reduced food safety risk of imported papaya. Mexican papaya contaminated with human pathogens caused multiple foodborne illness outbreaks resulting in hospitalizations and deaths. On urgent industry request, ARS scientists in Beltsville, Md., investigated effects of papaya packinghouse operations on cross-contamination and spread of Salmonella. We found that two disinfectants (chlorine and peracetic acid) can reduce but not eliminate Salmonella on papayas, and that the low risk of cross-contamination mediated by sponges or microfiber mitts can be managed by frequent dipping in these sanitizing solutions. Industry used these findings to develop science- and risk-based "Food Safety Best Practices for the Growing and Handling of Mexican Papaya" to improve food safety. Safer papayas benefit US consumers and improves US-Mexico trade relations. Identifeid new opportunities to improve food safety by accelerating bacterial die-off on fresh-cut produce. Pathogen contamination on fresh-cut produce has led to many foodborne illness outbreaks. Partnering with a major fresh-cut stakeholder, ARS scientists in Maryland showed that in simulated commercial conditions, silver citrate in combination with a commonly used process aid accelerate bacterial die-off on romaine lettuce during cold storage. The industry partner used the results to optimize treatment conditions and improve antimicrobial efficacy and food safety. Output Objectives 1 & 2 Following several Salmonella-mediated foodborne illness outbreaks traced to raw tomatoes, Florida's T-GAPs regulation mandated maintaining at least 150 ppm free chlorine (FC) in flume water. Recently, the industry asked if lower FC levels could be used. As part of our project, a University of Florida team performed packinghouse surveys and examined cross-contamination prevention using lower FC levels, with and without organic load. Results showed significant interaction between sanitizer concentration and Salmonella inoculant levels on cross-contamination. Findings were used to devise new tomato food safety regulations. Responding to recurring Salmonella outbreaks implicating papaya from Mexico, and to urgent needs to develop guidelines, we examined risks in postharvest washing and cleaning, especially the plausibility of sponge or microfiber wash mitts mediating cross-contamination during washing. Peracetic acid (PAA) and FC efficacy on papaya, and on sponge/ microfiber were also examined. Our results indicate that risks of sponge/microfiber mediating cross-contamination during washing can be mitigated by standardizing sanitizer monitoring and sponge/microfiber wetting. We evaluated susceptibility of three foodborne pathogens (Salmonella, Listeria, saiga-toxin producing E. coli) to commonly used sanitizers (chlorine and PAA) in leafy green wash water. Both sanitizers were highly effective. Pathogenic bacterial cells were less damaged after PAA treatment, with DNA protected by the cell membrane, raising concerns about inducing a viable but nonculturable (VBNC) state. However, potential VBNC cells were not resuscitated after various attempts, arguing against such concerns. We also examined microbial dynamics in wash water with FC or PAA as sanitizer. The microbiome in different wash waters converges to a core sanitizer-tolerant one, including multiple spore-forming bacteria. This information is useful in understanding wash water microbial dynamics and improving washing efficacy. We evaluated an abiotic surrogate for foodborne pathogens that can potentially be used to validate antimicrobial commercial food processing interventions. Safetracers are proprietary mixtures of DNA barcodes embedded in edible polymers such as polysaccharides, and can be quantitated by real-time PCR. We compared the ability of this DNA-based abiotic surrogate (DBAS) and E. coli O157:H7 to bind to spinach, as well as their removal/inactivation from spinach when washed in chlorinated water. E. coli O157:H7 and DBAS showed comparable inactivation at low FC levels typically used for leafy green washing. Our results show that DBAS might be a promising abiotic surrogate for on-site validation of anti-microbial processes targeting foodborne pathogens such as E. coli O157:H7. Current industry washing of fresh-cut produce uses two sequential flumes. The major challenge associated with flume washing is that abundant organic exudate is released from cut products, and rapidly depletes sanitizer, thus compromising microbiological safety. We made significant progress evaluating our novel in-flight washer (IFW; US Patent 10,285,411) in removing exudate before product enters the first flume, thereby improving sanitizer control and thus food safety and quality after packaging and during storage. Two IFW prototypes have been built, with configurable dimensions, water/air flow rates and directions. Trials have been conducted with numerous configurations, products (e.g., shredded lettuce, diced tomato and cabbage) and throughputs (25-150% of levels typical for commercial processing) to test organic removal capacity. Measuring turbidity and total dissolved solids, we found that the larger-diameter prototype, with multiple levels of directionally adjustable water/air nozzles was able to remove 50-60% of organic material released from shredded lettuce at 3,600 lb/hr throughput and a water input rate of 10 gal/min. These results demonstrate the potential of our invention to remove organic material from fresh-cut produce, thus promoting microbiological safety and product quality during storage. Objective 3 Our "wash-away" computations for soluble contaminant removal from behind a backward-facing step in a boundary layer flow, modeling the final "potable water" rinse to remove residual sodium hypochlorite from a rough produce surface, such as iceberg lettuce, have now been published, and show that considerable time is required to significantly reduce sanitizer concentration downstream of a topographical obstruction. The results strongly suggest that different flow regimes (e.g., a spray) will be more effective, and have the potential to greatly reduce contact time and water requirements. We have nearly completed computations of washout of a soluble viscosifying solute behind a backward-facing step, a good model of how organic exudate is removed in a flume wash, the importance of which is threefold. First, organic exudate reacts with and consumes hypochlorite ion, significantly complicating sanitizer concentration regulation. Second, exudate on the produce surface hinders access of hypochlorite, due to both reaction as well local increase in viscosity (thus reducing hypochlorite diffusivity). The computations show that the lower diffusivity of exudate (compared to hypochlorite ) is significant. We have made substantial progress in computing penetration of sanitizer through an exudate layer with which sanitizer reacts. This shows the importance of removing exudate before application of hypochlorite. When complete, they will inform decisions about "washing before sanitization". This has the potential to a) reduce formation of chlorinated by-products, chlorine consumption, and contact times, and improve sanitizer penetration to produce surfaces. Objectives 4 & 5 In partnership with major US retail chains (Publix, Wegmans, Raley's, and Hy-Vee), we have successfully completed large nationwide field studies on temperature control for food safety by retrofitting refrigerated display cases with doors. The analyisis of impact on produce sales and economics has been completed. We now also have the extension publications available online at the Iowa State University Extension Store website (Publications FS 36A, 36B, 37A, 37 B, and 38; https://store.extension.iastate.edu/Topic/Food-Nutrition-and-Health/Food-Safety?S=0&A=0&F=0 ). See "How have the results been disseminated to communities of interest?" section for detailed outreach activities for this project.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
de Frias, J.A, Luo, Y., Zhou, B., Ingram, D., Zhang, B., Vorst, K., and Brecht, J.K. 2020. Effect of door opening frequency and duration of an enclosed refrigerated display case on product temperatures and energy consumption. Food Control. 111: 107044. https://doi.org/10.1016/j.foodcont.2019.107044.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Gu, G., Ottesen, A., Bolten, S., Luo, Y., Rideout, S., and Nou, X. Microbiome convergence following sanitizer treatment in spinach and lettuce rinse water. Int. J. Food Microbiology. https://doi.org/10.1016/j.ijfoodmicro.2019.108458. Submitted: 09/29/2019; accepted; 11/21/2019; published: 11/23/2019.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Gu, G., Gonzalez-Escalona, N., Zheng, J., Bolten, S., Luo, Y., Mafiz, A., Leon, M.C., and Nou, X. 2020. Genome sequences of Brevundimonas naejangsanensis strain FS1091 and Bacillus amyloliquefaciens strain FS1092 isolated from a fresh-cut produce processing plant. Microbiology Resource Announcements. 9 (4) e01448-19. https://doi.org/10.1128/MRA.01448-19.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Gu, G., Bolten, S., Mowery, J., Luo, Y. Gulbronson, C., and Nou, X. 2020. Susceptibility of foodborne pathogens to sanitizers in produce rinse water and potential induction of viable but non-culturable state. Food Control. 112: 107138. https://doi.org/10.1016/j.foodcont.2020.107138.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Van Haute, S., Luo, Y., Bolten, S., Gu, G., Nou, X., and Millner, P.D. 2020. Survival of Salmonella enterica and shifts in microbial community as impacted by tomato wash water particulate size and chlorine treatment. Food Microbiology. 90:103470. https://doi.org/10.1016/j.fm.2020.103470.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Zhou, B., Luo, Y., Teng, Z., Pearlstein, D., Millner, P.D., and Pearlstein, A.J. 2021. Assessment of a novel in-flight washing device: microbial reduction and food quality of chopped iceberg lettuce during storage. Food Control. 120: 107538.
- Type:
Journal Articles
Status:
Published
Year Published:
2021
Citation:
Xie, Y., Brecht, J.K., Abrahan, C.E., Bornhorst, E.R., Luo, Y., Monge, A.L., Vorst, K., and Brown, W. 2021. Improving temperature management and retaining quality of fresh-cut leafy greens by retrofitting open refrigerated retail display cases with doors. J. Food Eng. 292, 110271 https://doi.org/10.1016/j.jfoodeng.2020.110271
- Type:
Journal Articles
Status:
Accepted
Year Published:
2020
Citation:
Xie, Y., Brecht, J.K., Abrahan, C., Luo, Y., and Bornhorst, E. 2020. Minimizing quality deterioration of fresh-cut baby spinach by retrofitting refrigerated retail display cases with doors. IV International Conference on Fresh-Cut Produce, Taian, China. Acta Hort. (in press)
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Monge, A.L., Brown, W., Brecht, J.K., Xie, Y., Bornhorst, E.R., Luo, Y., Zhou, B., Shaw, A. and K. Vorst. 2020. Temperature profiling of open and closed produce display cases in retail grocery stores. Food Control: 113: 107158; https://www.sciencedirect.com/science/article/abs/pii/S0956713520300748
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Min, D., Fischer, P.F. and Pearlstein, A.J., High Schmidt Number 'Washout' of a Soluble Contaminant Downstream of a
Backward-Facing Step. Int. J. Heat Mass Transfer, 159 (2020), 119740
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Brecht, J. Improving temperature management and retaining quality of fresh-cut leafy greens by retrofitting open refrigerated retail display cases with doors. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 8, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
de Frias, J.A., Luo, Y., Zhou, B., Teng, Z., Bornhorst, E.R. Chlorinated Water Injection in the Cutter of a Produce Washing System Reduces Bacteria Levels on Cut Produce Surfaces. ASHS Virtual Annual Conference, August 10-13, 2020. Available at https://ashs.confex.com/ashs/2020/meetingapp.cgi/Paper/33194
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Gu, G., Ottesen, A., Bolten, S., Mowery, J., Luo, Y., and Nou, X. Sensitivity of foodborne pathogens to chlorine and peracetic acid in sterile water and rinse water of spinach and lettuce. P3-120. International Association for Food Protection Annual Meeting. A Virtual Meeting, October 28, 2020.
- Type:
Journal Articles
Status:
Published
Year Published:
2020
Citation:
Yang, M., Cousineau, A., Liu, X., Luo, Y., Sun, S., Li, S., Gu, T., Sun, L., Dillow, H., Lepine, J., Xu, M., and Zhang, B. 2020 Direct metatranscriptome RNA-seq and multiplex RT-PCR amplicon sequencing on Nanopore MinION - promising strategies for multiplex identification of viable pathogens in food. Front Microbiol. 11:514. doi: 10.3389/fmicb.2020.00514.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Gu, G., Yin, H., Ottesen, A., Bolten, S., Patel, J., Luo, Y., and Nou, X. Effect of lettuce cultivar and irrigation water source on the dynamics of innate microbiota and survival of pathogenic E. coli and Salmonella spp. on lettuce. P3-121. International Association for Food Protection Annual Meeting. A Virtual Meeting, October 28, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Luo, Y. Dynamics of Human Pathogen, Native Microflora, and Product Quality under Elevated Storage Temperature. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 8, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Luo, Y. Monitoring Pathogen Cross-Contamination during Commercial Fresh Produce Wash using Indigenous Microflora The Association between Bacterial Survival and Antimicrobial Strength in Wash Water. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Luo, Y. Monitoring Wash Water Organic Load and Chlorine Demand Key parameters and their correlations. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Mendes Candido de Oliveira, G., Zhou, B., Pearlstein, D., Bolten, S., Gu, G., Park, E., Teng, Z., Turner, E., Millner, P.D., Nou, X., and Luo, Y. A Pilot-Plant Study Evaluating a New Technology to Accelerate Escherichia coli Die-Off on Fresh-Cut Lettuce during Cold Storage. P3-139. International Association for Food Protection Annual Meeting. A Virtual Meeting, October 28, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Millner, P.D. Advancing Our Understanding of Fresh-cut Washing Processes and Novel Technologies to Improve Disinfection Efficacy. Oral Presentation. University of Arizona Food Safety Conference. A Virtual Meeting, October 21, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Millner, P.D. Evaluation of a novel non-immersive fresh-cut produce wash during commercial operation. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 8, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Millner, P.D. Improving Food Safety of Packing House Tomato Wash. Oral Presentation. University of Arizona Food Safety Conference. A Virtual Meeting, October 21, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Millner, P.D. Preventing Salmonella cross-contamination during tomato dump tank operation the roles of sanitizer strength, plant debris, and particulates. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Millner, P.D. The use of ORP to estimate free chlorine in fresh produce washing operations: possibilities and limitations. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Nou, X. Evaluation of Salmonella cross-contamination associated with cleaning tools for papaya washing. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Nou, X. Microbiome dynamics on produce, in processing facility, and in wash water. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Pearlstein, A.J. Fluid Mechanics Computations for Removal of Organic Exudate and Residual Sanitizer from Fresh-Cut Produce. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 8, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Pearlstein, D. Wash produce vertically? Pilot plant trials of a novel in-flight washer. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 8, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Luo, Y. Packing House Operating Conditions and Tomato Varieties Effect on Infiltration of Human- and Plant-Pathogens and the Development of Market Disease. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Teng, Z. Identity, Prevalence, and Chlorine Demand of Major Organic Compounds in Fresh Produce Wash Water. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Thompson, G. Do Doors on Refrigerated Produce Display Cases Affect Sales of Fresh Processed Products? Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 8, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Xie, Y., Brecht, J.K., (Presenter), Abrahan, C., Luo, Y., and Bornhorst, E.R. Minimizing quality deterioration of fresh-cut baby spinach by retrofitting refrigerated retail display cases with doors. E-poster. IV International Conference on Fresh-Cut Produce, Tian, China August 12-17, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Pabst C.R, De, J., Smovzhenko, A., Schneider, K.R. Evaluating the Efficacy of Peroxyacetic Acid at Lower than Recommended Levels as a Sanitizer for Tomato Fluming Operations. Virtual International Association for Food Protection Annual Meeting. A Virtual Meeting, October 28, 2020.
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2019
Citation:
Monge-Brenes, A.L. 2019. Food safety in the retail environment. Dissertation. https://lib.dr.iastate.edu/etd/17750/
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Zhou, B. Monitoring microbial load in the presence of chlorine in wash water importance of sufficient chlorine neutralization. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 1, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Vorst, K. Effect of location and design of refrigerated display cases on temperature control of display cases. Oral presentation. Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-fresh-produce-food-safety-workshop), October 8, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2020
Citation:
Bourouiba, L. Fluids and sprays interaction with produce from small scales to large scales and back. Oral presentation.
Food Safety Innovations and Preventative Controls Virtual Workshop (https://www.producefoodsafety.org/virtual-freshproduce-food-safety-workshop), October 8, 2020.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Min, D., Fischer, P.F., and Pearlstein, A.J. High Schmidt number 'washout' of sodium hypochlorite or a viscosifying solute shielded by topography. 72nd Annual Meeting of the Division of Fluid Dynamics of the American Physical Society. Seattle, Wash., November 23-26, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Bertoldi B., De, J., Baker, C.A., Pabst, C.R., Gutierrez, A., and Schneider, K.R. Determining Water Quality and Bacterial Load on Tomatoes in Flume Tanks from Florida Packinghouses. IAFP annual meeting. Louisville, KY, July 21-24, 2019.
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Progress 09/01/18 to 08/31/19
Outputs
Target Audience:Our primary target audience is the fresh and fresh-cut produce industry (growers, processors, and equipment manufacturers), grocery stores, US government agencies, and international scientific communities. We have delivered science-based knowledge to these groups through a variety of means, including social media, our website, YouTube videos, site visits, face-to-face meetings, consulting, video conference calls, emails, meeting presentations, and peer-reviewed journal publications, as described below: Fresh and fresh-cut produce industry. We continue to engage the fresh and fresh-cut produce industry through service of its members on our stakeholder advisory board (SAB). Our project team members also serve on the Food Safety and Technology Council of the United Fresh Produce Association (UFPA), the leading industry organization. We have also organized and taught a fresh-cut produce workshop attended by more than 50 industry personnel, and shared our research during industry meetings. To support the industry effort in developing and implementing science- and risk-based food safety standards, project team members provided a webinar, per invitation from UFPA, on tomato dump-tank wash monitoring to the industry. We also hosted a tour at BARC for the Technical Committee of the Center for Produce Safety (CPS). The project team worked closely with major fresh-cut processors (Taylor Farms, SmartWashSolutions, Church Brothers Farms/True Leaf Farms, Lipman Produce) and a technology developer (Safe Traces) in our large pilot-plant scale at BARC and at the processors' facilities. Grocery stores. The retail industry is another major audience for our project given the importance of temperature control for food safety and the current technical challenges that this faces. We have worked with four retail chains to conduct in-store temperature monitoring of display cases with and without doors. In this current reporting period, we expanded that research to include additional studies to optimize case design and operation. The ISU team also developed science-based food safety educational curricula focusing on food safety best practices and sanitation within the grocery store environment. Food safety regulatory agency: FDA is an important stakeholder of our project as it pertains to science- and risk-based food safety regulations and industry standards. We have maintained close communication with the FDA through email, face-to-face meetings, and seminars. We have co-authored research publications, co-organized symposia, and provided consultation on an on-going and as-needed basis. National and international scientific community. We engaged and empowered the national and international scientific community through meeting presentations and publication sharing. Our team member at MIT worked with the French research agency CNRS to organize and host an eleven-day conference/summer school entitled "Fluids and Health", the first of its kind. Attendees included senior personnel from FDA, CDC, and leading universities in the US and Europe, as well as postdocs and graduate students (and one undergraduate). We gave more than 30 symposium talks, technical presentations, guest lectures, and webinars throughout the world, published 13 peer-reviewed journal articles, secured two issued patents, and filed one new patent application. We brought together industry technical personnel, FDA regulatory scientists, and academic researchers. We provided education and training to undergraduate and graduate students, and post-doctoral research associates. We also hosted site visits at BARC for multiple US and international entities, including the Taiwan Council of Agriculture, an Ethiopian agricultural delegation, Shanghai Jiao Tong University, and Rutgers University. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The team provided training, mentoring, and hands-on working experience to eight undergraduate students, two M.S. students, and six Ph.D. students, including two undergraduate students and two Ph.D. students of color. We also provided training and career development opportunities to seven post-doctoral research associates. We encouraged and supported graduate students and post-doctoral associates to attend professional meetings, symposia, and workshops, including those organized by the Institute of Food Technologists, International Association for Food Protection, the Center for Produce Safety, American Society for Horticultural Science, and the American Physical Society Division of Fluid Dynamics. We also facilitated training and certification for Ph.D. students in the Food Safety Modernization Act Produce Safety Grower Course, Food Safety Modernization Act Preventive Control for Human Food Course, and ServSafe through the National Restaurant Association. We fostered unique opportunities for students and post-doctoral research associates in engineering and life science to receive interdisciplinary training in food safety, produce processing, and microbiology through collaborative research, seminars, frequent conference calls, and site visits. The ARS team provided laboratory and fresh-cut processing pilot plant tours to more than 30 undergraduate students from the University of Maryland. The students interacted with our postdocs and participated in product quality evaluation. This provided a unique opportunity for students to learn and gain hands-on experience with produce processing. The work at UIUC provided direct exposure to produce washing issues for one postdoctoral research fellow and one PhD student. The postdoctoral fellow also participated in the 2019 Fluids and Health conference/summer school. At UIUC, we incorporated problems and findings relating to this project into three courses: TAM 536, "Instability and Transition" (a graduate course on hydrodynamic stability and transition) in Spring 2019; TAM 531, "Inviscid Flow" (a graduate fluid mechanics course for engineering students in multiple disciplines) in Fall 2019; and ME 320, "Heat Transfer" (a required undergraduate heat transfer course for mechanical engineering students) in Fall 2018 and Spring 2019. Recognizing the limited awareness in the fluid mechanics community of the importance of food safety, the UIUC team presented two talks at the annual meeting of the Division of Fluid Dynamics of the American Physical Society (APS-DFD): one on wash-away of contaminant downstream of a backward-facing step over a range of Schmidt numbers, and one on high Schmidt number 'washout' of a viscosifying solute downstream of a backward-facing step dealing with the case in which increasing the concentration of the solute increases the viscosity of the solution. At this conference, the MIT team also delivered three talks: one on novel validated algorithms developed for feature extraction and droplet image tracking for high-precision quantification of spray and atomization; one on the dynamics of fluid fragmentation selecting droplet size and speed relevant for optimization of spray drop impacts on contaminated fresh produce; and one on the role of biological surfactants secreted by bacterial contamination in changing the sizes and numbers of secondary contaminated droplets emitted from contaminated water, such as residual water in flume systems. Our team member at MIT organized and conducted an eleven-day conference/summer school in France from July 23 - August 2, 2019, with one week (five and one-half days) devoted to fluid dynamics and food safety, almost all of which was focused specifically on produce safety. This conference brought together an interdisciplinary group of fluid mechanicians, microbiologists, food safety regulators, agricultural water use experts, physicians, public health specialists, and environmental engineers from the FDA, CDC, the French Institute of Agriculture, the Connecticut Agricultural Experiment Station, as well as from leading universities in the US and Europe, to discuss produce food safety, and to expose an equally diverse set of about 50 postdocs, graduate students, and undergraduates to the issues. At the University of Florida, we incorporated scientific findings from this project into the UF course, HOS5085C, "Principles of Postharvest Horticulture," in Fall 2018. How have the results been disseminated to communities of interest? The project team has been very active in disseminating information to our major stakeholders, including the fresh and fresh-cut produce industry, retail industry, food safety regulatory agencies, and the international scientific community. Our means of communication include social media, our website, YouTube videos, site visits, face-to-face meetings, consulting, video conference calls, emails, and meeting presentations, as well as peer-reviewed journal publications. We published ten peer-reviewed journal articles, and delivered 29 scientific presentations on a broad range of scientific topics in the US and internationally. To reach out to the fresh-cut produce industry, project team personnel organized a fresh-cut workshop at UC Davis attended by more than 40 industry participants. We held a webinar for the produce industry regarding sanitizer monitoring, and provided consultation to numerous fresh-cut processors and tomato growers. To accelerate information sharing and industry stakeholder collaboration, we conducted research studies at SmartWashSolution's pilot plant in Salinas, CA, and Lipman Produce fresh-cut processing plant in New Jersey, and invited engineers and R&D scientists from Church Brothers Farms to visit our pilot-plant facility in Beltsville, MD. Through collaborative research and on-site monitoring, our team worked with four retail chains throughout the United States. We conducted observational food safety assessments, and based on those results developed science-based food safety educational curricula that focus on food safety best practices and sanitation within the grocery environment. Major foci include a) employee health and hygiene, b) handwashing, c) cross-contamination, d) stocking and rotation, e) handling of fallen produce, f) refrigeration and temperature control, g) display case cleaning, and h) maintenance. Training materials developed include two posters, four flipcharts, and one video. We disseminated scientific information and trainings through presentations at four national retailers and food safety conferences and five short courses that were attended by 81 participants in total. We delivered numerous presentations at conferences organized by the retail industry, including "Supermarket Sense Conference", "Fresh Summit Conference and Expo", and "Plastics Industry Association Fall Food Packaging Summit". In these industry-oriented conferences and expos, we interacted with retail store stakeholders and equipment manufacturers, and disseminated our research findings along with insights on new and innovative strategies for shelf-life extension of fresh and fresh-cut produce during retail distribution and display. Our website (https://www.producefoodsafety.org) has been frequently updated to disseminate project news, research activities, presentations, videos, and freely downloadable publications which we have uploaded. The ISU team has organized and hosted two food safety short courses: the "Produce Safety Alliance Grower Course" and the "Preventive Control for Human Food Course". What do you plan to do during the next reporting period to accomplish the goals?Objectives 1 and 2 We plan to extend research on the impacts of different sizes of suspended particulates on survival of inoculated (tagged) strains of E. coli O157:H7, Salmonella enterica, and Listeria monocytogenes in wash water, with and without different washing aids, across a range of sanitizers and concentrations, temperatures, and micron-size selective filtration, for lettuce and several types of tomatoes in fresh-cut processing. We first will conduct bench-scale studies, and then implement pilot-plant-scale studies to test the efficacy of pre-wash size filtration of recirculated wash water on reducing survival of inoculated bacterial pathogens. These studies will include characterization of survival responses of the indigenous microbial communities associated with particulates and the various treatment factors examined. ARS will investigate the shift in micrbial communities on various produce (including different varieties of leafy greens) and in production environment during processing and storage at refrigerated and abused temperature, and analyze the potential impact on the colonization and persistence of foodborne pathogens. ARS will investigate the residual disinfection byproduct on diced cabbage, diced tomato, and diced onion, as well as in the water collected from processing these products. Rationalle: preliminary study suggests a rapid drop in FC level from ~200 ppm to 0.5 ppm within seconds during single pass processing, suggesting an extremely fast reaction and potentially abundance of toxic byproducts. We plan to continue collaboration with Taylor Farms/SmartWashSolutions Inc., to test a hurdle technology that accelerates bacterial disinfection during wash and cold storage, thereby enhancing fresh-cut produce safety. Validation studies will be conducted as appropriate. Future studies of tomato packinghouse wash water and fruit samples will include impacts of temperature and selective size-filtration of micron-size particulates (pre- and post-wash), following our prior protocol with microbial analyses of water and fruits, and chemical analyses of wash tank water at collaborator sites in Florida. ARS and UIUC personnel will continue optimizing the design and perforamnce of the in-flight washer in terms of organic matter removal during fresh-cut produce washing. This may include the effects of nozzle configuration, angle of impact, and spray cone angles on organic matter. ARS will investigate chemical composition in cabbage and tomato wash water, along with chemical oxygen demand and chlorine demand. ARS will evalaute effectiveneess of novel technologies such as the inflight washer and vibra washer on pathgoen cross-contamination, compared to traditional flume washing. The UF team will complete statistical analysis of data on pathogen cross-contamination studies, and will submit two manuscripts for peer-reviewed publications. The ARS team expects to submit at least five manuscripts for peer-reviewed journal publication, deliver at least ten presentations at scientific meetings, and hold at least two webinars for the produce indsutry. Objective 3. The UIUC team plans to complete computations and submit two manuscripts relating to solute washout for publication in peer-reviewed journals: Min, D., Fischer, P.F., and Pearlstein, A.J. High Schmidt number 'washout' of a soluble contaminant downstream of a backward-facing step. Int. J. Heat Mass Transfer, submitted. Min, D., Fischer, P.F., and Pearlstein, A.J. High Schmidt number 'washout' of a viscosifying solute downstream of a backward-facing step. J. Fluid Mech., manuscript in preparation. The UIUC team will complete computations for the penetration of hypochlorite ion through gluconic acid and submit another manuscript in the second quarter of 2020. The UIUC team will also work closely with ARS personnel to translate our computational results into a publication suitable for a food safety journal. The MIT team will expand prediction and identify optimal regimes of removal, by spray-drop-impacts, of particulates from surfaces of complex geometries, in particular surfaces mimicking leafy green fresh produce. The MIT team will use the experimental platform developments of the past year to quantify precisely the effect of the surface and spray impacts on the removal of combined bacteria-particulate contamination. The MIT team will leverage the experimental protocol development and validation of the past year to quantify the mixing of fluids occurring upon spray drop impact on liquid films coating solid surfaces. This is important to study the regimes of optimal deposition of sanitizers on wet surfaces, such as pre-rinsed fresh produce, and evaluate the ratio of penetration to loss of the sanitizer from such wet produce surfaces. This work will interface with the work of the UIUC team on the dynamics of penetration of hypochlorite ion at the surface micron scale. Objective 4. The UF team intends to complete data analysis and submit a mansucript for a peer-reviewed publication: Xie, Y., Brecht, J.K., C The ISU team (Vorst and Shaw) will complete data analysis and submit the following two manuscripts for peer-reviewed publications: Monge-Brenes, A., Brown, W., Brecht, J.K., Xie, Y., Bornhorst, E.R., Luo, Y., Zhou, B., Shaw, A. and Vorst, K. 2019. Temperature profiling of open and closed produce display cases in retail grocery stores. Food Control Bhullar, M., Monge-Brenes, A., Perry, B., Nabwiire, L., and Shaw, A. 2019. Determining the potential food safety risk associated with dropped produce on floor surfaces in the grocery store. Food Protection Trends Flip Chart Training material: Employee Health and Hygiene-Managers Objective 5. The ISU team (Vorst) will give an invited talk at the Food Manufacturers Institute (FMI) Fresh Executive Committee and Fresh Foods Leadership Council in early 2020. The focus of the presentation is forward thinking strategies on food product display including fresh and fresh-cut product to increase sustainability awareness, and reduce spoilage and cost. This conference will be attended by executive-level management including personnel from our project sponsors such as Wegmans, Publix, Hy-Vee, and other large brand owners and stakeholders such as Target, Walmart, SuperValu and Kroger. The ISU team (Shaw) will complete the following training materials and disseminate them to stakeholders: Poster: Food Safety in the Supermarket Poster: Display Case Best Practices Video: How to Clean a Display Case Flip Chart Training material: Handwashing Flip Chart Training material: Stocking and Rotation Flip Chart Training material: Employee Health and Hygiene-Employees
Impacts
What was accomplished under these goals?
Impact Commercial produce wash water accumulates organic matter, which reacts with and depletes chlorine, helping bacteria survive. Project teams at ARS and UIUC patented a novel "in-flight" wash system to remove organic matter early in the process. The new process exposes all produce surfaces to sanitizer, thus improving process control and wash efficacy. This system also allows exceptionally efficient use of vertical space in processing areas. An on-site demonstration was provided to the produce industry during a group visit organized by the United Fresh Produce Association and attended by more than 50 industry technical leaders. Church Brothers Farms is currently working with the team to scale up the test towards commercial applications. We completed a large undertaking with major US retail chains (Publix, Wegmans, Raley's, and Hy-Vee) in monitoring the temperature in refrigerated produce display cases with and without doors. Display cases from different store chains, regions, seasons, and operating conditions were evaluated. Our large data set, obtained under commercial retail conditions for the first time, demonstrated benefits of door installation in reducing temperature abuse and facilitating compliance with the US Food Code regarding temperature control for food safety. We also identified numerous opportunities to further improve case design and operation, and provided recommendations to retailers and case designers. Output Objectives 1 & 2 We expanded our wash water study to investigate particulate-mediated pathogen cross-contamination, specifically the effects of wash water turbidity and size-selective filtrationon cross-contamination and sanitizer efficacy. We reported significant effects of chlorine treatment and particulate size on the microbial community. For tomato dump-tank wash water, results clearly showed that Salmonella cells in free suspension are readily inactivated by free chlorine (FC) at less than 100 mg/L, but those associated with particulates are protected, and can serve as vectors for cross-contamination. Findings contribute to the body of knowledge and directly benefit the produce industry. We investigated how sanitizer (hypochlorous acid) routinely used in fresh-cut produce washing affects microbiomes of surviving organisms. Results demonstrate that repeated addition of sanitizer to spinach and lettuce wash water gradually reduces the microbiome richness of the water, resulting in survival dominance of Gram-positive and spore-forming bacteria, mainly Bacillus spp. Inoculated foodborne pathogens (EHEC, Salmonella, and Listeria) were not isolated among sanitizer-resistant strains. We also analyzed the microbiome in a commercial fresh-cut produce processing facility and documented the identities and relative abundances of bacteria as impacted by typical equipment and sanitation practices. Collaborating with Taylor Farms/SmartWashSolutions Inc., the project team evaluated a hurdle technology to reduce pathogens in fresh-cut lettuce. We found that a fine-mist pre-treatment of a trace concentration of commercially available, food-grade, silver-ion solution significantly accelerates E. coli die-off during cold storage, opening the door to developing approaches to accelerate more general bacterial die-off during cold storage and improve fresh-cut produce safety. We analyzed tomato wash water and fruit samples (pre- and post-wash) in representative Florida packinghouses, at operational start-up and hourly, for water chemistry (pH, free chlorine, turbidity, temperature, total dissolved solids, chemical oxygen demand, etc.). Bacterial analyses (total plate counts, total coliforms, and E. coli) of water and fruit samples were conducted to assess efficacy of chlorine in preventing cross-contamination during washing. Findings were shared with the industry. Objective 3 The UIUC team completed computations to model the removal of residual sodium hypochlorite from a rough produce surface, like iceberg lettuce, finding that in a typical boundary layer flow regime (as in flume washing), considerable time is required to significantly reduce the amount of sanitizer residue. Results strongly suggest that different flow regimes (e.g., a spray) will improve the efficacy of this function, and have the potential to greatly reduce contact time and water requirements. The UIUC team also made substantial progress in computations investigating the removal of exudate that reacts with and consumes sanitizer. When incorporated into a wash system where exudate is washed off before sanitization, this work will provide the theoretical basis for a) reducing the formation of chlorinated by-products, b) reducing chlorine consumption, c) reducing required contact times, d) improving sanitizer penetration to produce surfaces, and e) improving control of chlorine concentration in wash systems. The MIT team developed and validated physical and theoretical models to investigate fluid break-up and droplet size and speed distributions under a range of dynamic conditions. They also expanded on previous work, developing and validating models of stresses, fluid retention, and fluid removal on surfaces impacted by spray drops, including surfaces with complex geometries that mimic produce such as spinach. The MIT team also developed an optical experimental platform to directly visualize and quantify both the removal of bacteria and micron-scale particles from produce surfaces by droplet impacts, and to investigate spray impacts on surfaces that have liquid films. This work will provide insight into the efficacy of spray configurations and inform the design of novel spray systems. Finally, they also developed experimental protocols for simulating bacterial and particulate removal from produce surfaces at varying levels of desiccation. Objective 4 Collaborating with major US retail chains (Publix, Wegmans, Raley's, and Hy-Vee), we completed a large study monitoring temperature in refrigerated produce display cases with and without doors across different store chains, regions, and seasons. Results demonstrated benefits of installing transparent doors in reducing temperature abuse and complying with US Food Code regarding temperature control for food safety. We identified numerous opportunities to further improve case design and operation, and shared recommendations with retailers and case manufacturers. These include: a) new coatings on display case doors, lights, and side panels to reduce light degradation and intensity; b) product placement for optimal airflow during high traffic retail shopping hours; c) display case location to optimize customer traffic flow and minimize case door interference, thus improving the shopping experience and increasing product turnover; and d) temperature profile data to optimize cooling cycles during peak and off-peak shopping hours. We also made many food safety observations and provided targeted training and education to store employees. Objective 5 Economics: We continued evaluating sales of fresh produce in grocery stores that retrofitted their refrigerated display cases with doors to maintain product temperatures within US Food Code requirements. We examined weekly sales data before and after retrofits at four stores of a regional supermarket chain, for 52 weeks prior to, and 52 weeks after, retrofitting. Generally, retrofit had no statistically detectable impact, positive or negative, on total store sales, sales of all produce items, or sales of fresh-processed produce items. Weekly temperature had little impact on total store sales, but was statistically significant in explaining differences in produce and fresh-processed vegetable sales. Results helped to alleviate potential concerns that door installation to improve US Food Code compliance might negatively impact sales. Extension: Extensive outreach activities are detailed in "How have the results been disseminated to communities of interest?"
Publications
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Nou, X., Luo, Y., and Millner, P. Listeria monocytogenes growth potential, kinetics, and factors affecting its persistence on a broad range of fresh produce. Center for Produce Safety Research Symposium. Austin, Tex., June 18-19, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Pearlstein, A.J. Fresh-cut produce washing: State-of-the-art, alternatives, and the role of organic exudate. Invited talk, Fluids and Health 2019 Conference and Summer School. Carg�se, France, August 1, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Pearlstein, A.J. Fluid mechanics of produce washing. Invited talk, Fluids and Health 2019 Conference and Summer School. Carg�se, France, July 30, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Poulain, S. and Bourouiba,L. Bubbles at contaminated water interfaces. 71st Annual Meeting of the Division of Fluid Dynamics of the American Physical Society. Atlanta, Ga., November 18-20, 2018.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Shaw, A.. FSMA Produce, Processing, and Holding. Oral Presentation. Ohio Produce Network. Dublin, Ohio, January 16-17, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Van Haute, S., Luo, Y., Zhou, B., Sampers, I., Vanhaverbeke, M., and Millner, P.D. Effect of wash water matrix on the correlation between free chlorine and oxidation-reduction potentials during fresh produce washing operations. International Association of Food Protection Annual Meeting. Louisville, Ky., July 23, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Van Haute, S., Luo, Y., Bolten, S., Gu, G., Nou, X., Zhou, B., and Millner, P.D. Influence of suspended particulates from harvest debris on Salmonella survival in chlorinated whole tomato wash water. International Association of Food Protection Annual Meeting. Louisville, Ky., July 23, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Vorst, K. Retail innovation. Oral Presentation. Supermarket Sense Conference. Conyers, Ga., September 18-19, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Vorst, K. Retail innovation. Oral Presentation. Produce Manufacturers Association (PMA) Fresh Summit Conference and Exp. Anaheim, Calif., October 17-19, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Vorst, K. Food Packaging in Retail. Plastics Industry Association Fall Food Packaging Summit. Savannah, Ga., November 12-14, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Zhou, B., Luo, Y., Teng, Z., Nou, X., and Millner, P.D. Impact of Field Debris on Tomato Wash Water Quality Deterioration. P2-199. International Association of Food Protection Annual Meeting. Louisville, Ky., July 23, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Zhou, B., Luo, Y., Millner, P.D., and Pearlstein, A.J. Washing Efficacy of In-flight Washer on Fresh-cut Produce. Beltsville Agricultural Research Center Poster Day. Beltsville, Md., 2019.
- Type:
Theses/Dissertations
Status:
Submitted
Year Published:
2019
Citation:
Lejeune, S. 2018, Fragmentation of a drop impacting near the edge of a solid substrate, doctorate thesis, Bourouiba MIT Co-advisor. Submission to Department of Engineering Science, Liege University, Belgium.
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2020
Citation:
Alsved, M., Bourouiba, L., Duchaine, C., Londahl J., Marr, L., Parker, S., Prussing II, A., and Thomas, R. Natural sources and experimental generation of bioaersols: Challenges and Perspectives. Aerosol Science and Technology. (in press).
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2020
Citation:
Bolten, S., Gu, G., Luo, Y., Van Haute, S., Zhou, B., Millner, P.D., Micallef, S.A., and Nou, X. Salmonella inactivation and cross-contamination on cherry and grape tomatoes under simulated wash conditions. Food Microbiology. (in press). https://doi.org/10.1016/j.fm.2019.103359
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Gu, G., Ottesen, A., Bolten, S., Wang, L., Luo, Y., Rideout, S., Lyu, S., and Nou, X. Impact of routine sanitation on the microbiomes in a fresh produce processing facility. International Journal of Food Microbiology. 294 (2019) 31-41.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Gu, G., Yin, H.-B., Ottesen, A., Bolten, S., Patel, J., Rideout, S., and Nou, X. Microbiomes in Ground Water and Alternative Irrigation Water, and Spinach Microbiomes Impacted by Irrigation with Different Types of Water. Phytobiomes. 3 (2019) 137-147.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Guan, Y., Teng, Z., Mei, L., Zhang, J., Wang, Q., and Luo, Y. An entrapped metal-organic framework system for controlled release of ethylene. Journal of Colloid and Interface Science. 533 (2019) 207-215.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Huang, J., Luo, Y., Zhou, B., Zheng, J., and Nou, X. Growth and Survival of Salmonella enterica and Listeria monocytogenes on fresh-cut produce and their juice extracts: Impacts and interactions of food matrices and temperature abuse conditions. Food Control 100 (2019) 300-304.
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Li, J., Teng, Z., Weng, S., Zhou, B., Turner, E.R., Vinyard, B.T., and Luo, Y. Dynamic changes in the physicochemical properties of fresh-cut produce wash water as impacted by commodity type and processing conditions. PLoS ONE (2019) 14(9).
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Luo, Y., Zhou, B., Van Haute, S., Nou, X., Zhang, B., Teng, Z., Turner, E.R., Wang, Q., and Millner, P.D. Association between bacterial survival and free chlorine concentration during commercial fresh-cut produce wash operation. Food Micro. 70 (2018) 120-128.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Poulain, S. and Bourouiba, L. Biosurfactants change the thinning of contaminated bubbles at bacteria-laden water interfaces. Physical Review Letters 121 (2018) 204502.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Teng, Z., Van Haute, S., Zhou, B., Hapeman, C.J., Millner, P.D., Wang, Q., and Luo, Y. Impacts and interactions of organic compounds with chlorine sanitizer in recirculated and reused produce processing water. PLoS One (2018). 13 (12).
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Van Haute, S., Zhou, B., Luo, Y., Sampers, I., Vanhaverbeke, M., and Millner, P. The use of redox potential to estimate free chlorine in fresh produce washing operations
- Type:
Journal Articles
Status:
Published
Year Published:
2019
Citation:
Wu, Y., Luo, Y., Zhou, B., Mei, L., Wang, Q., and Zhang, B. Porous metal-organic framework (MOF) Carrier for incorporation of volatile antimicrobial essential oil. Food Control 98 (2019) 174-178.
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2020
Citation:
Xie, Y., Brecht, J.K., Abrahan, C., Luo, Y., and Bornhorst, E.R. Minimizing quality deterioration of fresh-cut baby spinach by retrofitting refrigerated retail display cases with doors. Acta Horticulturae. (in press).
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Zhang, B., Luo, Y., Kanyuck, K., Saenz, N., Reed, K., Zavalij, P., Mowery, K., and Bauchan, G. Facile and template-free solvothermal synthesis of mesoporous/macroporous metalorganic framework nanosheets. RSC Adv. 58 (2018) 33059-33064.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Bertoldi, B., De, J., Baker C., Pabst C., Gutierrez A., and Schneider, K. Determining Water Quality and Bacterial Load on Tomatoes in Flume Tanks from Florida Packinghouses. P2-185. International Association for Food Protection Annual Meeting. Louisville, Ky., July 23, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Bhullar, M. and Shaw, A. Retail Produce Safety Drop. Oral and Poster Presentation: North Central Region Center for Food Safety Modernization Act Training, Extension, and Technical Assistance Annual Conference. Indianapolis, Ind., June 11-12, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Bhullar, M., Monge, A., Perry, B., Nabwiire, L., and Shaw, A. Determining the potential food safety risks associated with dropped produce on floor surfaces in retail stores. International Association for Food Protection Annual Meeting. Louisville, Ky., July 23, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Bolten, S., Gu, G., Van Haute, S., Zhou, B., Millner, P., Luo, Y., Micallef, S.A., and Nou, X. Salmonella inactivation and cross-contamination on cherry and grape tomatoes during washing in simulated commercial wash water. International Association for Food Protection Annual Meeting. Louisville, Ky., July 23, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Bourouiba, L. Unsteady fluid fragmentation. Applied Mathematics Colloquium, New Jersey Institute of Technology. Newark, N.J., February 22, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Bourouiba, L. Fluid fragmentation. Mechanical and Aerospace Engineering, Princeton University. Princeton, N.J., April 12, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Bourouiba, L. Fluid dynamics for agricultural disease control and food systems. Invited lecture, Aspen Global Change Institute. Basalt, Colo., August 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Bourouiba, L. Fluids and Health. Invited SEARS public lecture, Woods Hole Oceanographic Institution. Woods Hole, Mass., August 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Bourouiba, L. Pathogen transmission from surfaces: drop impacts and interactions. Invited talk, Living Systems Institute (LSI), University of Exeter. Exeter, UK, September 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Bourouiba, L. Unsteady fluid fragmentation. Keynote talk, 29th European Conference on Liquid Atomization and Spray Systems (ILASS). Paris, France, September 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Clotilde, L., Nou, X., Luo, Y., Wilhelmsen, E., Idoine, A., Zhou, B., Bolten, S., Gu, G., and Zografos, A. 2019. Evaluation of abiotic bacterial surrogates for validation and verification of one-pass produce wash systems. International Association for Food Protection Annual Meeting. Louisville, Ky., July 22, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Gu, G., Bolten, S., Van Haute, S., Zhou, B., Luo, Y., Rideout, S., and Nou, X.. Potential for Salmonella cross-contamination during tomato washing and pre- and post-wash commingling. International Association for Food Protection Annual Meeting. Louisville, Ky., July 23, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Luo, Y. Food Safety Innovations and Preventive Controls for Leafy Greens and Tomatoes. ARS/FSIS Food Safety Workshop. Shepherdstown, W. Va., February 20-22, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. and Wang, Y. Rim thickness evolution in unsteady sheet fragmentation. 71st Annual Meeting of the Division of Fluid Dynamics of the American Physical Society. Atlanta, Ga., November 18-20, 2018.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Luo, Y. Controlled Environment Agriculture - The Heightened Importance of Seeds to Food Safety. American Seed Trade Association. Orlando, Fla., January 5, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2018
Citation:
Luo, Y., Van Haute, S., Zhou, B., Teng, Z., and Millner, P. D. Tomato dump tank water monitoring. Webinar. United Fresh Produce Association. October 9, 2018.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Millner, P.D. Farm-to-Fork: Salad in a Bag! Can Aquaponics fit the Supply Chain. Invited Deans Seminar, School of Agricultural and Natural Sciences, University of Maryland Eastern Shore. Princess Anne, Md., October 3, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Millner, P.D. Science and technology challenges and opportunities for improving fresh and fresh-cut food safety: Farm-to-Fork, 1890 Association of Research Directors, Research Conference, Speaker and Co-organizer, Special Session on Food Safety and Associated Water Quality. Jacksonville, Fla., April 2, 2019.
- Type:
Conference Papers and Presentations
Status:
Other
Year Published:
2019
Citation:
Millner, P.D. Organic Carbon and Food Safety of Fresh Produce. ARS/FSIS Food Safety Workshop. Shepherdstown, W. Va., February 20-22, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Min, D., Fischer, P.F., and Pearlstein, A.J. High Schmidt number 'washout' of sodium hypochlorite or a viscosifying solute shielded by topography. 72nd Annual Meeting of the Division of Fluid Dynamics of the American Physical Society. Seattle, Wash., November 26, 2019.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2019
Citation:
Monge, A., Vorst, K., and Shaw, A. Effect of location and design of refrigerated display cases on temperature control in retail stores. International Association of Food Protection Annual Meeting. Louisville, Ky., July 23, 2019.
|
Progress 09/01/17 to 08/31/18
Outputs
Target Audience:Our primary target audience is the fresh and fresh-cut produce industry, grocery stores, US government agencies, and international scientific communities. We have delivered science-based knowledge to these communities through a variety of means, as described below: Fresh and fresh-cut produce industry is our primary stakeholder. We have invited industry technical specialists from fresh-cut processing companies and industry associations to serve on our stakeholder advisory board (SAB). Our project team members also serve on the Food Safety and Technology Council of the United Fresh Produce Association (UFPA), the leading industry organization. We also serve as members or leaders on the working groups of various food safety programs of importance to our research programs and the industry. We have hosted the Food Safety and Technology Council meeting in our facility and provided technical briefings and facility tours to more than 50 technical executives from the industry. We also organized a fresh-cut produce workshop attended by more than 50 industry personnel. Most importantly, at a critical juncture when tomato food safety guideline development was hindered by the lack of scientific information concerning pathogen cross-contamination in relation to chlorine concentration, we responded to the call from the industry immediately. We moved our ARS research lab from Beltsville, Maryland to Naples, Florida and worked alongside industry personnel to evaluate the effects of tomato packinghouse operating conditions on microbial populations. We then simulated tomato dump tank conditions in the laboratory and conducted additional pathogen cross-contamination studies. Our results were shared with the industry through webinars, frequent email communications, and face-to-face meetings. We also reviewed the industry tomato food safety guidelines and contributed significantly their successful, on-time publication. Grocery stores are another targeted audience. We have worked with four retail store chains and conducted in-store temperature monitoring of display cases with and without doors. We have reached out to employees and management within the retail grocery sector, by conducting observational food safety assessments and using those results to develop science-based food safety educational curricula focusing on food safety best practices and sanitation within the grocery environment. We provided consultation to two grocery chains on the food safety results and impacts of sanitation and employee training. Additionally, when we noticed that one of the collaborating stores had unusually low temperature due to inadequate adjustment of the duty cycle following door installation, we contacted the collaborating store manager promptly and helped the store to avoid product freezing. We engaged and empowered the national and international scientific community through meeting presentations and publication sharing. In this past reporting year, we organized three technical sessions/symposia during annual meetings of the Institute of Food Technologists, the International Association for Food Protection, and the American Society for Horticultural Sciences, bringing together industry technical personnel, FDA regulatory scientists, and academic researchers. We gave more than 30 symposium talks, technical presentations, guest lectures, and webinars throughout the world, and published ten peer-reviewed journal articles. We provided education and training to undergraduate and graduate students, and post-doctoral research associates. We also developed a new curriculum to train our future work force in fresh-produce washing and safety. 1890 Institutions. Project team members organized and hosted, with the 1890 Institution's Association of Research Directors, the Second Food Safety Consortium Symposium at the USDA-ARS - Beltsville Agricultural Research Center, in Beltsville, MD. Over 100 attendees, from 19 of the 1890 institutions, industry, and several grant funding agencies, participated. The attendees met with project team members and toured the research facility. The project PD shared the team's accomplishments, research activities, and internship opportunities with the attendees. Fluid mechanics community. Recognizing the limited awareness in the fluid mechanics community of the importance of produce safety (or more generally, food safety), we presented a talk at the annual meeting of the Division of Fluid Dynamics of the American Physical Society (APS-DFD) on wash-away of contaminant downstream of a backward-facing step over a range of Schmidt number. We also presented another APS-DFD talk on high Schmidt number 'washout' of a viscosifying solute downstream of a backward-facing step dealing with the case in which the concentration of the solute increases the viscosity of the solution. In the course on hydrodynamic stability and transition (Theoretical and Applied Mechanics 536: "Instability and Transition") at the University of Illinois at Urbana-Champaign (UIUC), there is a section (three two-hour lectures on boundary layer stability and transition. In Spring 2018, 21 graduate students heard a one-hour lecture on the case in which the viscosity depends on a transported scalar (temperature or species concentration) and used the case of a viscosifying solute (and in particular organic exudate in fresh-cut processing) as an example. (Some of these students had been exposed to a 10-minute discussion of the importance of fluid mechanics in fresh-cut processing the previous Fall semester in the foundational course TAM 531.) The required undergraduate heat transfer course for mechanical engineering students at UIUC (ME 320) contains brief coverage of mass transfer. (This course, for which one semester of fluid mechanics is prerequisite, is the only exposure to mass transfer in any required course for these students.) In one section of this course during Fall 2018, the 38 students were exposed to a 10-minute discussion of the importance of diffusive and convective mass transfer in fresh-cut processing. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The team provided training, mentoring, and hands-on working experience to five undergraduate students at the University of Maryland, ISU, and MIT. We also trained one M.S. student each at the University of Florida and University of Arizona, a total of five Ph.D. students at ISU, MIT, and UIUC, and a total of six post-doctoral researchers at MIT, UIUC, and USDA-ARS. We encouraged and supported graduate students and post-doctoral associates to attend professional meetings, symposia, and workshops, including those organized by the Institute of Food Technologists, International Association for Food Protection, the Center for Produce Safety, American Society for Horticultural Science, and the American Physical Society Division of Fluid Dynamics. We also provided training and certification to a Ph.D. student for the Food Safety Modernization Act Produce Safety Grower Course, Food Safety Modernization Act Preventive Control Human Food and Animal Food Courses and ServSafe through the National Restaurant Association. Most importantly, we fostered unique opportunities for students and post-doctoral research associates in engineering and life science to receive inter-disciplinary training in food safety, produce processing, and microbiology through collaborative research, seminars, frequent conference calls, and site visits. We brought a postdoc from UIUC to meet with her experimental collaborators at MIT, and to meet microbiologists at ARS for cross-training. We provided training to faculty and students from historically black colleges (1890 schools), and mentored one student of color at ISU. We provided laboratory and fresh-cut processing pilot plant tours to more than 30 undergraduate students from the University of Maryland. The students interacted with our postdocs and participated in product quality evaluation. This provided a unique opportunity for students to learn and gain hands-on experience with produce processing. How have the results been disseminated to communities of interest? The project team has been very active and productive in outreach and disseminating information to our major stakeholders, including the fresh and fresh-cut produce industry, retail industry, food safety regulatory agencies, and the international scientific community. Our means of communication include social media, our website, YouTube videos, site visits, face-to-face meetings, consulting, video conference calls, emails, and meeting presentations, as well as peer-reviewed journal publications. We hosted the annual food safety and technology council meeting of UFPA at our facility, and provided tours to the attendees (more than 50). Industry personnel visited our fresh-cut produce pilot plant and research supermarket, watched the videos and slideshows featuring project accomplishments, engaged in hands-on activities with our patent-pending instruments, and interacted with our team members. Great feedback was received from the industry. To further reach out to the fresh-cut produce industry, project team personnel organized a fresh-cut workshop at UC Davis attended by more than 40 industry participants. We also shared project findings during an industry food safety council meeting attended by more than 60 industry technical executives. In addition, we participated in a working group involving members of USDA and FDA, and other food safety researchers, on topics at the interface between mathematical modeling and empirical data. Another important stakeholder group that we have reached out to is the retail industry, where temperature control is important to food safety, but challenging to maintain. Through collaborative research and on-site testing, our team worked with four retail chains throughout the United States. We reached out to employees and management within the retail grocery market. We conducted observational food safety assessment, and based on those results we are developing a science-based food safety educational curricula that focuses on food safety best practices and sanitation within the grocery environment. Our research team also interacted broadly with the international scientific community concerning produce food safety, time and temperature control for food safety, and fluid dynamics of produce washing. We disseminated findings through scientific publications and presentations in the US and international platforms, as well as classroom technical and hands-on lab practices. We educated and trained many undergraduate and graduate students and post-doctoral research associates. One unique aspect of our project is the focus on fluid dynamics and produce sanitization. Currently, there is little awareness in the fluid dynamics community of the importance of produce safety (or more generally, food safety), and our talks at the annual meeting of the American Physical Society Division of Fluid Dynamics help to fill the void. In addition, we presented talks at international conferences, including in France, the USA, and Canada and at a summer school held at MIT, in addition to special lectures on this topic in a class taught at MIT on Fluids and Health, focusing on food safety and agriculture. We are also in the process of organizing a conference for summer 2019 which will further raise awareness on these topics. We also include our research in the development of new curricula to train students. At UIUC, we included some discussion of produce washing in a foundational fluid mechanics course in 2017, exposing 17 engineering graduate students (from four graduate curricula) to the issues and importance of this application, with which none were previously familiar. In 2018, 21 students in a specialized graduate course on hydrodynamic stability received one hour of instruction on the effects of a viscosifying solute on boundary layer stability, with discussion of the fresh-cut processing application in which this is important. Developed and launched a new website (http://producefoodsafety.org) featuring research progress, news, reports, peer-reviewed papers, trade journal publications, fact sheets, patents and patent applications, archived seminars, videos, and other resources. We provided many site tours to companies that may provide additional innovations to develop food safety solutions. These include tours for Vanguard delegations, a United Kingdom Precision Agriculture Innovation Center delegation, Emerson Automation, Heinzen Manufacturing International (HMI), Coastal Manufacturing, Spraying Systems Co., Optimized Thermal Systems, Inc., and BETE Fog Nozzle, Inc. FDA is an important stakeholder of our project as it pertains to science- and risk-based food safety regulations and industry standards. We have maintained close communication with the FDA with emails, face-to-face meetings, and seminars. We have co-authored research publications, and co-organized symposia, and provided consultation on an on-going and as-needed basis. The team also made on-site visits and performed experimental trials at stakeholder processing facilities during regular production. What do you plan to do during the next reporting period to accomplish the goals?Objectives 1&2 ARS will complete investigation on the impact of particulates on pathogen survival and cross-contamination during fresh-cut leafy green washing and tomato dump tank handling processess. We expect to submit 1-2 manuscripts for peer-reviewed journal publications, and 1-2 webinars to share findings with indsutry stakeholders. ARS will expand the studies to inlcude pre-washing rinse with stabilized silver ion (via collaboration with SmartWash Solutions) to further improve pathogen reduction during produce washing. ARS will complete pilot-scale single-pass and flume wash systems fabrication and installation, and initiate side-by-side comparisons of pathogen reduction and cross-contaminaiton prevention between these sysems. ARS and UIUC personnel will continue evaluating the performance of the in-flight washer in terms of organic matter removal, microbial reduction, and cross-contamination prevention, water usage, and produce quality and shelf life. The system will be further optimized to reduce water consumption, increase throughput, and enhance microbial reduction. ARS will evaluate the effect of nozzle configuration, angle of impact, and spray cone angles on organic matter and microbial removal and water usage. ARS will complete investigation of chemical compostion in Romaine and Iceberg letuce and wash water chemical oxygen demand and chlorine demand. ARS will evaluate the potential of using a range of microorganisms as surrogates for pathogenic E.coli O157:H7, Salmonella spp., and Listeria monocytogenes, in terms of their response to chlorine treatment, and their suitability for microbial lethality studies, in pilot-plant studies. UF will complete testing the effects of organic loading on cross-contamination. The study will analyze COD levels of 0, 100 and 300 ppm (based on the findings of our in-plant surveys conducted this past year) challenged with FC levels of 0, 50, and 100 mg/L. The study will utilize a five-strain cocktail of Salmonella to determine cross contamination. The initial inoculation level on tomatoes will be 1.0 x 104 CFU/tomato to address concerns of high inoculum levels used in previous experiments. This study will set chlorine levels first before addition of organic load. Presence/absence testing will be used to determine the potential of cross-contamination potential Objective 3 UIUC will complete work on, and submit (to the International Journal of Heat and Mass Transfer) the first computational paper (two-dimensional unsteady "wash-away" of a soluble contaminant behind an obstruction) before January 1, 2019. UIUC will complete the two-dimensional computations for "wash-away" of a viscosifying solute whose concentration affects liquid viscosity sometime in December 2018. One manuscript will be submitted to the Journal of Fluid Mechanics. UIUC will resume and complete the computations of penetration of sanitizer through fluid which consumes it (i.e., hypochlorite diffusing through organic exudate). These computations should be complete during the second quarter of 2019. MIT will complete the full modeling and validation of sheet coating of surfaces and fragmentation for a range of impacting different fluids and impacted surfaces to be representative of larger range of sanitizers and produce surfaces. MIT will collaborate with UIUC and ARS in furthering studies on the role of roughness and size of target surface on changing the spray impact efficacy for washing and cleaning. The surface physics influences the spreading of the spray drop after impact, which can therefore affect removal efficacy during spreading. This will be done in collaboration with UIUC for rough surface mimics used in computation modeling, and with ARS for mimicking surfaces that more realistically represent roughness of fresh produce, and micro-organism characterizations when we move to the final stages of biological materials. We will study the role of viscosity on residual fluid in grooves in collaboration with UIUC, designing artificial mixtures that mimic the range of viscosities the team recently measured from organic exudates. Objective 4 ISU and UF teams will complete data analysis of retail store display case temperature mapping. Information available to public will include differences between case with and without doors, and additional temporal and special factors such as variations among months, stores, case load (Altoona and Des Moines), and product positions within the display cases. UF will continue evaluation of product quality comparisons for spinach and fresh-cut Romaine lettuce. ISU and UF expect to complete and submit two manuscripts for peer-reviewed journal publications and visit with the retailers (in January 2019) to discuss impact of open- and closed-door display cases on shelf life and cost savings at the retail level. Objective 5 Project team will publish at least ten research articles in peer-reviewed or trade journals featuring research progress. Frequently update website content to reflect project activitites. Continue to hold quarterly project team and Stakeholder Advisory Board meetings to discss project activities and stakeholder needs, and for the stakeholders to evaluate project performance. UF will develop a training fact sheet on the correct way to measure free chlorine and other water quality parameters. Publication is targeted for Spring 2019. The team will co-host (in collaboration with the UC Davis Post-harvest Center) a fresh-cut workshop for industry stakeholders. ISU extension team will further develop produce food safety education for US retailers through in-store research on the effects of open and closed display case. The team is now developing extension decision-making tools for retailer management and employees. As a result of this observational study, a microbial research study was conducted in the summer of 2018 to evaluate the risk of microbial attachment on produce dropped in the grocery store. This publication is currently in review for publication. Sanitation and employee training related to cross contamination and Food Code will be translated into on-demand videos, quick-facts sheets, and extension publications. Products will include cleaning of display cases, best-practices guide for grocery store produce aisles, focusing on food Safety knowledge builders for grocery store employees and management.
Impacts
What was accomplished under these goals?
Impact The project has generated two results with significant industrial impact, supporting development and implementation of science- and risk-based food safety policies and practices. The UFPA has submitted these impacts to USDA-NIFA on our behalf as detailed below: For the US to realize the benefits of tomatoes as a source of minerals, vitamins, and phytonutrients, high consumer confidence in tomato safety must be maintained. Personnel from USDA-ARS and the University of Florida (UF) partnered with Florida tomato growers and packers to address critical food safety data gaps. The industry used the findings to develop "Commodity Specific Food Safety Guidelines for the Fresh Tomato Supply Chain," adoption of which will reduce microbial hazards associated with fresh and fresh-cut tomatoes. Washing produce can remove harmful bacteria and reduce food-safety risk; improper washing can spread bacteria and increase risk. ARS personnel identified key operating conditions (including sanitizer concentration) affecting bacterial survival and transference during washing. An industry and a multi-agency taskforce used our findings to develop "Guidelines to Validate Control of Cross-Contamination during Washing of Fresh-Cut Leafy Vegetables". Our findings were also cited by the FDA as a scientific basis for the newly released "Draft Guidance for Industry: Guide to Minimize Food Safety Hazards of Fresh-cut Produce" to implement science- and risk-based food safety policies in support of Food Safety Modernization Act (FSMA). Output Objectives 1 & 2 Based on an industrial request to support food safety standards development, we conducted large-scale studies of tomato dump tank handling conditions and Salmonella cross-contamination. ARS and UF personnel documented current packinghouse operating conditions. The ARS team matched wash conditions in its laboratory to those in commercial settings. Freshly harvested cherry tomatoes were washed concurrently with tomatoes and field debris inoculated with distinguishable strains of Salmonella at a range of free chlorine (FC) levels (5-150 mg/L). Salmonella was not recovered from spent wash water at any FC level. However, sporadic Salmonella cross contamination on uninoculated tomatoes sometimes occurred even at high FC levels. In those rare cases, contaminating Salmonella more frequently originated from inoculated debris than inoculated tomatoes, pointing to the former as an important contamination source, and suggesting that debris removal prior to washing can significantly improve food safety. We further examined the removal of wash water particulate on bacteria survival. We observed that the abundance of spore and endospore-forming Gram-positive bacteria increased as particle size decreased, indicating that early removal of stem and leaf debris from dump tanks can aid microbial reduction. "Single-pass" washing, in which water contacts the produce once and is not recirculated, is a recent industry development designed to reduce pathogen cross-contamination risk. In collaborating with our industry partner, the ARS team compared produce quality and shelf life, and water and chemical usage between single-pass and flume systems for the first time. Results were shared with the industry to aid in developing and optimizing new washing processes. We also developed an automated in-line dosing/mixing system for 0-50 mg/L FC (exceeding the currently available commercial FC limit of 20 mg/L) and acidulants to adjust pH at any FC level, providing processors increased flexibility to dose/monitor FC and sanitizers at high concentrations. Oxidation-Reduction Potential (ORP) is a popular measurement used to quickly estimate FC in wash water. But no data on the ORP-FC relationship are available for typical commercial conditions. We evaluated the ORP/FC/pH relationship for such conditions, showing that ORP-FC follows a log-linear relationship ("ORP-LogFC") at fixed pH, and delineating additional factors such as organic matter type and concentration influencing ORP-LogFC. Suggestions for developing ORP-LogFC relationships for specific industrial washing processes are included in a manuscript being prepared. Objective 3 The UIUC team studied "washout" of soluble material from fresh-cut produce during washing. We measured viscosity of aqueous sodium gluconate solutions over 2-25°C at concentrations up to near saturation. These measurements, the first for a six-carbon sugar acid below 25°C, are relevant to typical 4°C fresh-cut processing. We performed the first computations of washout of soluble contaminant from a rough produce surface, providing quantitative data on time needed for such removal, and showing the importance of tailoring wash water flow to the application. Our computations support the hypothesis that organic exudate removal prior to washing not only reduces chlorinated by-product formation, but also facilitates sanitizer penetration to produce surfaces and reduces FC depletion. They also provide guidance to design washing processes removing viscosifying solutes prior to sanitizing wash steps; when completed, this will inform decisions about "washing before sanitization", i.e., a two-step process washing off exudate before sanitization. At MIT, we delineated drop impact regimes for viscous sessile drops on large surfaces. For viscosity mimicking produce exudate, we determined regimes of efficient removal or mixing for surfaces with wettability similar to produce leaves. To improve coating and washing, we examined how impact leads to spray-drop formation. We developed algorithms to extract key break-up features and derived a universal criterion describing such break-up, robust to variation in fluid viscoelasticity and surface roughness. We quantified time-varying emission of secondary droplets from drop impact on finite surfaces. For optimal coating and sanitizing, these emissions would induce loss of sprayed fluid upon impact with a produce surface, whose dynamics and geometric regimes we characterized. Objective 4 ISU and UF personnel monitored temperature in open and closed display cases in matched pairs of stores for four retailers (eight stores in total) nationwide. Temperature was also mapped before and after door installation. Results indicate significant reduction in temperature, after door installation, confirming previous results obtained in the research supermarket. The team observed that the temperature dropped too low after installation in some stores, and advised the stores to increase the refrigeration set point, helping the stores avoid freezing damage. The upward adjustment of the set point also is expected to reduce energy consumption. Energy analyses and product quality evaluation are underway, although technical challenges are expected due to confounding factors associated with electrical connections of display cases in stores, and many other uncontrollable factors impacting product quality. Objective 5 See also the section "How have the results been disseminated to communities of interest". Economics For a regional grocery chain, the University of Arizona team identified four stores in which doors had been retrofitted to refrigerated displays, and analyzed the impact on fresh-processed produce sales, comparing weekly scanner data before/after door installation in geographically distinct areas. An econometric model accounts for effects of price, with data from NOAA (daily weather), IRS (adjusted gross income), and the Census Bureau (demographics) as control variables. Results will be used to inform grocery chains in other regions of the significance of this research in relation to their operations.
Publications
- Type:
Theses/Dissertations
Status:
Published
Year Published:
2018
Citation:
Lobo, A. 2018. Two-Stage Estimation of Elasticities for Disaggregated Salad Products, M.S. thesis, Department of Agricultural and Resource Economics, University of Arizona.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Bornhorst, E.R., Luo, Y., Park, E., Vinyard, B.T., Nou, X., Zhou, B., Turner, E., Millner, P.D. 2018. Immersion-free single-pass, commercial fresh-cut produce washing system: An alternative to flume processing. Postharvest Biology and Technology. 146:124-133.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
de Frias, J.A., Luo, Y., Zhou, B., Turner, E., Millner, P.D., and Nou, X. 2018. Minimizing pathogen growth and quality deterioration of packaged leafy greens by maintaining optimum temperature in refrigerated display cases with doors. Food Control. 92:488-495.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Gu, G., Ottesen, A., Bolten, S., Ramachandran, P., Reed, E., Rideout, S., Luo, Y., Patel, J., Brown, E., Nou, X. 2018. Shifts in spinach microbial communities after chlorine washing and storage at compliant and abusive temperatures. Food Microbiology. 73. August 2018: 73-84.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Guan, Y., Luo, Y., Teng, Z., Zhou, B., Mei, L., Bauchan, G.R., and Wang, Q. 2018. A novel sensing chip for probing chlorine permeation into simulated produce cracks. Advanced Materials Interfaces. 5(13):1800119.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Teng, Z., Luo, Y., Alborzi, S., Zhou, B., Chen, L., Zhang, J., Zhang, B., Millner, P., Wang, Q. 2018. Investigation on chlorine-based sanitization under stabilized conditions in the presence of organic load. International Journal of Food Microbiology. 266:150-157.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Van Haute, S., Luo, Y., Sampers, I., Mei, L., Teng, Z., Zhou, B., Bornhorst, E.R., Wang, Q., Millner, P. 2018. Can UV absorbance rapidly estimate the chlorine demand in wash water during fresh-cut produce washing processes? Postharvest Biology and Technology. 142:19-27.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Wang, Y. and Bourouiba, L. 2018. Non-isolated drop impacts. Journal of Fluid Mechanics. 835:24-44.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Wang, Y. and Bourouiba, L. 2018. Unsteady sheet fragmentation: Droplet sizes and speeds. Journal of Fluid Mechanics. 848:946-967.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Wang, Y., Dandekar, R., Bustos, N., Poulain, S., and Bourouiba, L. 2018. Universal rim thickness in unsteady sheet fragmentation. Physical Review Letters. 120: 204503.1-6.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Lejeune, S., Gilet, T., and Bourouiba, L. (2018) Edge-effect: Liquid sheet and droplets formed by drop impact close to an edge. Physical Review Fluids. 3, 083601.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Guan, Y., Teng, Z., Mei, L., Zhang, J., Wang, Q., and Luo, Y. An entrapped metal-organic framework system for controlled release of ethylene. J. Colloid & Interface Science. 533: 207-215. 2018.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bolten, S., Clotilde, L., Gulbronson, C., Gu, G., Luo, Y., Micallef, S. A., Zografos, A., Nou., X. 2018. Detachment Kinetics of Escherichia coli O157:H7 and Nonliving Surrogate from Surface of Spinach. International Association for Food Protection Annual Meeting, Salt Lake City, UT.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bornhorst E.R., Luo Y., Park E., Vinyard B.T., Nou X., Zhou B., Turner E., Teng Z., and P.D. Millner. 2018. Evaluation of commercial washing processes for fresh-cut produce: traditional flume and novel single pass systems. Institute of Food Technologist Annual Meeting, Chicago, IL.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bornhorst E.R., Park E., Zhou B., Hutton, B.T., Simko, I., and Luo Y. 2018. Comparison of the Browning Potential of Fresh-cut Romaine Lettuce Cultivars during Cold Storage, Beltsville Agricultural Research Center Poster Day, Beltsville, MD.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bornhorst E.R., Park E., Zhou B., Turner E., Simko I., and Y. Luo. 2018. Comparison of the browning potential of fresh-cut Romaine lettuce during cold storage. American Society for Horticultural Science Annual Meeting, Washington, DC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Mechanistic modeling of pathogen transmission. Keynote speaker at the Infectious Bioaerosols Special Symposium, 10th International Aerosol Conference.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Unsteady fluid fragmentation, plenary keynote lecture at the 2018 Engineering Mechanics Institute Conference, Cambridge, MA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Mechanistic multi-scale modelling of infectious diseases transmission, Workshop on Modeling Biological Phenomena from nano to macro scales, Fields Institute, Toronto, Canada.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Unsteady fragmentation. School of Engineering Fluid Mechanics Seminar, Stanford University, Stanford, CA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Disease transmission. American Mathematical Society Special Session "Modeling of Biological Processes" Spring Eastern Sectional Meeting, Boston, MA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. The fluid dynamics of disease transmission: drop impacts and transfer of pathogens, INRA and AgroParisTech, Paris, France.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Unsteady fragmentation, Institut d'Alembert, CNRS and Universit� Pierre et Marie Curie, Paris, France.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Mechanistic understanding of disease transmission. Keynote speaker at the Darwin Science Festival Week, Salem, MA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Fluids and Health. Keynote speaker at "A Two-day Centenary Celebration of Jule Charney and Ed Lorenz, Lorenz Center, Cambridge, MA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Bourouiba, L. 2018. Contamination via fluid fragmentation and multiphase flows. Keynote speaker at the Porous Materials for Energy and Environment Winter School, Marseille, France.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Brecht, J.K., Xie, Y., Luo, Y., Bornhorst, E.R., Vorst, K., and Brown, W. 2018. Closed-door refrigerated retail display cases for whole and fresh-cut produce: Are temperature management and product quality improved? American Society for Horticultural Science Annual Meeting, Washington, DC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
de Frias, J.A., Luo, Y., Zhou, B., Turner, E., Millner, P.D. and Nou, X. 2018. Food quality and safety assessment of packaged leafy greens after storage in a refrigerated display case with doors. American Society for Horticultural Science Annual Meeting, Washington, DC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Gu, G., Ottesen, A., Bolten, S., Wang, L., Luo, Y., Rideout, S., Lyu, S., Brown, E., Nou, X. 2018. Effect of Routine Sanitation and Surface Material on the Shift in Microbial Communities in Fresh Produce Processing Environments. International Association for Food Protection Annual Meeting, Salt Lake City, UT.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Gu, G., Yin, H., Ottesen, A., Bolten, S., Patel, J., Rideout, S., Nou, X. 2018. Dynamics of Microbial Communities on Spinach Irrigated by Ground Water, Reclaimed Water, and Roof-harvest Water. International Association for Food Protection Annual Meeting, Salt Lake City, UT.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Gu, G., Xu, Y., Zheng, J., Bolten, S., Reed, E., Luo, Y., Nou, X. 2018. RNA-Seq analyses on Listeria monocytogenes and Ralstonia insidiosa mono- and dual-species growth and biofilm formation. American Society for Microbiology Annual Meeting, Atlanta, GA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Huang, J., Zhou, B., Zheng, J., Nou, X., and Luo, Y. 2018. Survival and Growth of Salmonella and Listeria Monocytogenes on Fresh-Cut Fruits and Radish under Different Temperature Abuse Conditions. American Society for Horticultural Science Annual Meeting, Washington, DC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Hutton, B.T., Bornhorst E.R., Park E., and Luo Y. 2018. Image analysis of fresh-cut produce to determine visual quality, Beltsville Agricultural Research Center Poster Day, Beltsville, MD.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Liu, X., Yang, M., Luo, Y., and Zhang, B. 2018. Detection of Foodborne Pathogens via Paper Chromogenic Array. Institute of Food Technologist Annual Meeting, Chicago, IL and Gordon Research Conference, South Hadley, MA.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Luo, Y. 2018. Challenges and research opportunities for maintaining food safety and quality of fresh produce during washing, packing, and retail display. 2nd 1890 Association of Research Directors and United States Department of Agriculture, Agricultural Research Service Food Safety Symposium, Beltsville, MD.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Millner, P.D. 2018. Fresh and fresh-cut produce food safety- meeting technical challenges with advances. American Society for Horticultural Science Annual Meeting, Washington, DC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Min, D., Fischer, P.F., and Pearlstein, A. J. High Schmidt number 'washout' of a viscosifying solute downstream of a backward-facing step. presentation at the 71st Annual Meeting of the Division of Fluid Dynamics of the American Physical Society, November 18-20, 2018, Atlanta, Ga.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Nou, X. 2018. Spinach microbiome shifts following chlorine wash and ensuing storage. University of Maryland Plant Symposium- Joint Symposium with the American Society of Plant Biologists, College Park, MD.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Nou, X., Bolten, S., Gu, G., Van Haute, S., Zhou, B., Millner, P.D., and Luo, Y. 2018. Prevention of Salmonella contamination on tomatoes during simulated dump-tank washing. American Society for Horticultural Science Annual Meeting, Washington, DC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Teng, Z., Van Haute, S., Zhou, B., Hapeman, C., Millner, P., Wang, Q., and Luo, Y. 2018. Identity, Prevalence, and Chlorine Demand of Major Organic Compounds in Fresh Produce Wash Water. Beltsville Agricultural Research Center Poster Day, Beltsville, MD.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Teng, Z., Van Haute, S., Zhou, B., Hapeman, C., Millner, P., Wang, Q., and Luo, Y. 2018. Investigation on the major sources of organic load and chlorine demand in fresh-cut product wash water. American Society of Horticultural Science Annual Meeting, Washington, DC.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Zhang, B., Luo, Y., Liu, X., Yang, M. 2018. Novel strategy for rapid quantification of viable pathogens - electrochemical BioMEMS. Institute of Food Technologist Annual Meeting, Chicago, IL.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2018
Citation:
Zhou, B., Luo, Y., Huang, L., Yan, H., and Huang, J. 2018. Exposure to elevated temperatures during early vs late storage, differently affects the rate of microbial quality deterioration in commercially packaged baby spinach. Beltsville Agricultural Research Center Poster Day, Beltsville, MD.
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Progress 09/01/16 to 08/31/17
Outputs
Target Audience: Our primary target audience is the fresh and fresh-cut produce industry. For this group, we invited many industry technical specialists from leading fresh-cut processors and industry associations to serve on our stakeholder advisory board (SAB). Our project team members serve on the Food Safety and Technology Council at the produce industry association, and made significant contributions to the drafting and revising of industry-led white papers. We co-organized a working group with food safety researchers and USDA and FDA personnel on issues relating to mathematical modeling and empirical data of produce washing. Another important target audience is the retail industry. Temperature control of displayed products is critical to food safety, yet difficult to achieve. Our team is working to address these challenges through collaborative research with four USA retail chains. A third targeted audience was the international scientific and academic community. We presented symposium talks and seminars throughout the world and published our research findings in peer-reviewed journals and trade magazines. We provided education and training to undergraduate and graduate students, and post-doctoral research associates. We also developed new curriculum to train our future work force in fresh-produce washing and safety. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The team provided training, mentoring, and hands-on working experience to three undergraduate students at the University of Maryland, one M.S. student at University of Florida, a total of five Ph.D. students at Iowa State University, MIT, and University of Illinois, and a total of seven post-doctoral researchers at MIT, University of Illinois, and USDA-ARS. We encouraged and supported graduate students and post-doctoral associates to attend professional meetings, symposia, and workshops, including those organized by the Institute of Food Technologists, International Association for Food Protection, the Center for Produce Safety, and the American Physical Society Division of Fluid Dynamics. Most importantly, we fostered unique opportunities for students and post-doctoral research associates in mechanical engineering and life science to receive inter-disciplinary training in food safety, produce processing, and microbiology through collaborative research, seminars, frequent conference calls, and site visits etc. How have the results been disseminated to communities of interest? The project team has been very active and productive in outreach and disseminating information to our major stakeholders, including the fresh and fresh-cut produce industry, retail industry, food safety regulatory agencies, and the international scientific community. Our means of communication include social media, our website, YouTube videos, site visits, face-to-face meetings, consulting, video conference calls, emails, and meeting presentations, as well as peer-reviewed journal publications. Within the first two weeks of project approval, we held our first project team and stakeholder advisory board (SAB) meetings in conjunction with the industry's public policy conference held in Washington, D.C. The team interacted with SAB members and laid out solid plans for collaboration, fulfillment of milestones, and measurement of success. We held four additional quarterly conference calls with the SAB and shared our findings with the industry. To reach out to the fresh-cut produce industry, project team personnel organized a fresh-cut workshop at UC Davis attended by more than 60 industry participants. The PD and two Co-PIs of our project shared our project findings with the attendees. We also shared project findings during an industry food safety council meeting attended by more than 70 industry technical executives. We further contributed to industry sponsored "white papers" widely distributed throughout the entire produce industry. In addition, we co-organized a working group involving members of USDA and FDA, and other food safety researchers, on topics at the interface between mathematical modeling and empirical data, and provided technical consultations to numerous fresh produce companies, as well as site tours. Another important stakeholder group that we have reached out to is the retail industry, where temperature control is important to food safety, but challenging to maintain. Through collaborative research and on-site testing, our team worked with four retail chains throughout the United States. Our research team also interacted broadly with the international scientific community concerning produce food safety, time and temperature control for food safety, and fluid dynamics of produce washing. We disseminated findings through scientific publications and presentations in the US and international platforms, as well as classroom technical and hands-on lab practices. We educated and trained many undergraduate and graduate students and post-doctoral research associates. One unique aspect of our project is the focus on fluid dynamics and produce sanitization. Currently, there is essentially no awareness in the fluid dynamics community of the importance of produce safety (or more generally, food safety), and our talks at the annual meeting of the American Physical Society Division of Fluid Dynamics helps to fill the void. In addition, we presented symposium talks and seminars internationally, including in France, Greece, Singapore, and China. We also include our research in the development of new curricula to train students. At the University of Illinois, we included some discussion of produce washing in a foundational fluid mechanics course, exposing 17 engineering graduate students (from four graduate curricula) to the issues and importance of this application, with which none was previously familiar. At MIT, we developed a curriculum, and are training students on disease transmission,sprays,and surface science. At the USDA-ARS, we offered tours to more than 30 undergraduate students from the University of Maryland, and mentored five post-doctoral research associates on food safety research. We developed and launched a new website (http://producefoodsafety.org) featuring the project activities, publications, poster presentations, and videos. What do you plan to do during the next reporting period to accomplish the goals?Objective 1 Conduct on-site survey of commercial tomato packinghouse operation including the dynamic changes of free and total chlorine, ORP, organic load, and microbial survival. Investigate the effect of free chlorine and ORP in the presence of varying organic load on pathogen cross-contamination during simulated tomato dump tank operations. Assess the role of chemical classes and their presence in relation to organic load, chlorine demand, and chlorine dosing scheme of diverse fresh-cut produce. Objective 2 Complete installation of chlorine dosing system of the single-pass wash system at the USDA-ARS pilot plant. Evaluate the effect of nozzle configurations on the removal of bacteria and foreign materials from fresh and fresh-cut produce during single-pass wash operation. Objective 3 Complete the two-dimensional computations for "wash-away" of a solute whose concentration affects liquid viscosity, as well as the computations of penetration of sanitizer through fluid which consumes it (i.e., hypochlorite diffusing through organic exudate). Investigate droplet fragmentation during impact on surfaces for a range of controlled roughness and relevant physical properties of the fluid solutions in wash system for a range of produce. Objective 4 Complete summary of the first set of temperature measurements at collaborating retail chains. Work with the retail industry to solve technical challenges in order to facilitate energy monitoring once door installation is optimized. Evaluate packaged salad sales trends in correlation with door installation to display cases. Begin to evaluate various mechanisms for optimizing display case operation, considering temperature, energy consumption, and produce quality and shelf life. Objective 5 Publish at least ten research articles in peer-reviewed or trade journals featuring research progress. Frequently update website content to reflect project activities. Continue to hold quarterly project team and stakeholder advisory board meetings. Co-host (in collaboration with the UC Davis Post-harvest Center) a fresh-cut workshop for industry stakeholders. Host a stakeholder workshop in conjunction with either the Center for Produce Safety Symposium to be held in Charlotte, N.C., or the United Fresh Produce Public Policy Conference to be held at Washington.
Impacts
What was accomplished under these goals?
Impact Preparation of packaged, fresh-cut, "triple washed", "ready-to-eat" vegetables relies on use of wash water sanitizers, like chlorine, to prevent bacterial pathogen contamination. The integrated multi-disciplinary approaches taken by the project engineers, microbiologists, and food scientists uncovered myths behind the penetration of sanitizer through a layer of exudate, and developed new visualization techniques and a state-of-the-art image processing algorithm to delineate and quantify the outcome of drop impacts on produce surfaces. Information gained from this project enables fresh-cut processors to improve food safety by systematic rather than trial-and-error approaches. The project team also invented a novel fresh-cut washing system that improves the washing process efficacy and filed a nonprovisional patent application. Our team's research with four multi-state retail grocery chains is showing significant improvements in control and compliance with food code temperatures during display of fresh-cut produce in refrigerated cases, with the added benefit of major conservation of energy. Our project website provides easy access to project activities and workshop trainings on water sanitation practices to industry personnel, and accomplishments for stakeholders. Output Objectives 1 & 2: The project team comprehensively evaluated the major sources of chemical oxygen demand, and chlorine demand in wash water of diced cabbages. We characterized the types/contents of sugars, phenolic compounds, organic acids, proteins and peptides in the produce wash water, but chiefly, their roles in depleting free chlorine. Diced cabbage is known to present major challenges to maintaining required free chlorine levels during commercial washing. Delineation of these important chemical classes and their abundance in wash water fills critical data gaps on produce food safety, and paves the road for safe and effective wash water treatments. We conducted microbial community analyses on spinach and the environment in a commercial fresh-cut processing facility using DNA sequencing to determine the effects of sanitizer and storage conditions on changes in the natural resident bacterial populations. Results can inform processors about potential contamination routes, thereby improving product/environmental sanitation. We developed a method based on dual-wavelength ultraviolet light absorbance (UVA) to predict real-time chlorine demand during produce washing. Using cut cabbage, carrot, lettuce, and onion as model food products, we showed that UVA changes relative to the amount of organic material in the water and the residual chlorine demand. This method forms a basis for development of an automated chlorine control replenishment system in continuous commercial produce washing processes. In collaboration with an industry partner, the first research unit of a single pass wash system was fabricated and installed in our pilot plant. On-going research studies focus on improving the washing efficacy of the single-pass system by optimizing water nozzle types and configurations in collaboration with two leading nozzle manufacturers. Objective 3: We fabricated and tested our novel produce wash system for cleaning fresh-cut produce immediately after cutting, and submitted a nonprovisional patent application. As produce falls downward, a spray manifold directs fluid upward to spray and impact the tumbling produce, thereby thoroughly coating/cleaning it. Computations of the capacity to wash away a soluble contaminant, such as plant tissue exudate or residual chlorine, from a rough produce surface, will provide major insight into the flow velocities and thicknesses required. Using a computational fluid dynamics approach, we have nearly completed analyses of "wash-away" scenarios for characteristic 2-D roughness elements. These are the first detailed convective mass transfer computations performed for any nontrivial flow in any geometry at a Schmidt number over 10. Results suggest that different flow regimes (e.g. spray) would effectively wash away a contaminant and potentially reduce contact time and wash water requirements. Further computations will include characteristic 3-D roughness elements and 3-D topographies from actual produce surfaces. We also measured the viscosity of aqueous solutions over a range of temperatures to use in our computations; these are the first such data for any six-carbon sugar acid. We are currently working on computations for the penetration of sanitizer through a layer of exudate, including the reaction of sanitizer with exudate to understand the importance of removing exudate before the application of hypochlorite. When complete, these computations will inform decisions about "washing before sanitization" We are also conducting research on fresh produce to examine impact dynamics of spray drop shape on particulate matter removal, sanitizer deposition, and rinsing. Our team established the scientific basis for fundamentally new approaches to improve the process of spray washing of produce and sanitizer deposition. We developed new visualization techniques, and a state-of-the-art image processing algorithm to delineate/quantify the outcome of drop impact on produce surfaces and the role of the drop speed, size, and fluid properties when coupled with surface roughness of produce. These findings revealed key factors in fluid retention on surfaces after impact from spray drops. Our ongoing work focuses on mixing during spray impact on dry, rough, and pre-wetted surfaces. The fundamentally novel mathematical models and physics we developed can be used to improve produce washing, sanitizing, and rinsing to optimize pathogen control. Objective 4: Our research with four different multi-state retail chains involves continuous data collection (180 temperature/relative humidity sensors in refrigerated display cases) in 10 grocery stores. Data has helped our industry partners deal with key issues with retrofitting doors on display cases. We also identified potential air flow and contamination collection points during temperature monitoring in various case locations. Our team recommended changes to best practices for temperature control in closed display case settings and showed that implementing these changes can result in 90% reduction in warm temperature abuse. We worked with store- and chain-level management to improve maintenance and improve safety and consumer experience. Objective 5: Extension activities are detailed in the "How have the results been disseminated to communities of interest" section. Economics We have made significant progress in assembling data needed to assess potential impacts of installing doors on refrigerated display cases. We successfully negotiated agreements with a sales data provider and were granted secure access to store-level, weekly sales data on all items sold in most supermarkets in the USA. To begin compiling weekly sales data at the store level, we determined the relevant identifiers for fixed-weight fresh-processed products (UPCs) and random-weight fresh products (IRI data sets), and more than 3,000 UPCs of potential interest. Prospective candidates for measuring potential impacts of display-case doors on sales have been selected. Detailed data on three classes of factors (store, neighborhood, weather) that can affect weekly sales in different locations are being assembled for use in accounting for the impact of door installation on refrigerated display cases on store sales of packaged fresh-cut produce. This work has provided a solid foundation for our data analysis.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Gombas, D., Luo, Y., Brennan, J., Shergill, g., Petran, R., Walsh, C., Khurana, K., Zomorodi, B., Rosen, J., Varley, R., and Deng, K. 2017. Guidelines to validate control of cross-contamination during washing of fresh-cut leafy vegetables. Journal of Food Protection. 80(2):312-330.
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
Luo, Y., Zhou, B., Van Haute, S., Nou, X., Zhang, B., Teng, Z., Turner, E., Wang, Q., and Millner, P.D. 2018. Association between bacterial survival and free chlorine concentration during commercial fresh-cut produce wash operation. Food Microbiology. 70:120-128.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Mei, L., Teng, Z, Zhu, G., Liu, Y., Zhang, F., Zhang, J., Li, Y., Guan, Y., Luo, Y., Chen, X., and Wang, Q. 2017. Silver nanocluster-embedded zein films as antimicrobial coating materials for food packaging. ACS Applied Materials & Interfaces. 9(40):35297-35304.
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Sun, X., Zhou, B., Luo, Y., Ference, C.M., Baldwin, E.A., Harrison, K., and Bai, J. 2017. Effect of controlled-release chlorine dioxide on the quality and safety of cherry/grape tomatoes. Food Control. 82:26-30.
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2017
Citation:
Zhou, B., Luo, Y., Bauchan, G., Feng, H., and Stommel, J. 2017. Visualizing pathogen internalization pathways in fresh tomatoes using MicroCT and confocal laser scanning microscopy. Food Control. In press. https://doi.org/10.1016/j.foodcont.2017.09.027
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
Wang, Y. and Bourouiba, L. 2017 Drop impact on small surfaces: thickness and velocity profiles of the expanding sheet in the air. Journal of Fluid Mechanics. 814:510-534.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Bourouiba, L. and Wang Y. 2017. Binary drop interaction on surfaces: onset and bounding ligaments of Crescent-Moon fragmentation. Oral presentation, 70th Annual Meeting of the Division of Fluid Dynamics of the American Physical Society, Denver, CO.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Gu, G., Bolten, S., Wang, L., Rideout, S., and Nou, X. 2017. Impact of Washing Process and Storage on the Shift of Spinach Microbiota. Poster presentation, International Association for Food Protection Annual Meeting, Tampa, FL.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Gu, G., Ottesen, A., Bolten, S., Wang, L., Ramachandran, P., Reed, E., Rideout, S., Luo, Y., Brown, E., and Nou, X. 2017. Shift in Microbial Communities in Fresh Produce Processing Environments Before and After Routine Sanitization. Poster presentation, Joint conference of the Capital Area Food Protection Association and DC chapter of the American Society of Microbiology, College Park, MD.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Min, D., Fischer, P. F., and Pearlstein, A. J. 2017. Wash-away of contaminant downstream of a backward-facing step over a range of Schmidt number. Presentation, 70th Annual Meeting of the Division of Fluid Dynamics of the American Physical Society, Denver, CO.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Nyarko, E., Kniel, K., Zhou, B., East, C., Handy, E., Luo, Y., Millner, P., and Sharma, M. 2017. Practices and Conditions Which Promote Persistence of Listeria monocytogenes on Equipment Surfaces and Transfer to Cantaloupes in the Packing Environment. Poster presentation, International Association of Food Protection Annual Meeting, Tampa, FL.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Luo, Y., Zhou, B., Zhang, B., Nou, X., Van Haute, S., Turner, E., Teng, Z., Wang, Q., and Millner, P. 2017. Dynamic Changes in Water Quality and Microbial Survival during Commercial Fresh-cut Produce Wash Operation. Poster presentation, International Association of Food Protection Annual Meeting, Tampa, FL.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Teng, Z., Luo, Y., Alborzi, S., Zhou, B., Zhang, B., Millner, P., and Wang, Q. 2017. Chlorine-based Inactivation of Escherichia coli O157:H7: Impact of Residual-free Chlorine Content, Organic Load, Residence Time, and pH. Poster presentation, International Association of Food Protection Annual Meeting, Tampa, FL; Beltsville Agricultural Research Center Poster Day, Beltsville, MD.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Wang, Y., and Bourouiba, L. 2017. Unified thickness profile of radially expanding sheets in the air. Oral presentation, 70th Annual Meeting of the Division of Fluid Dynamics of the American Physical Society, Denver, CO.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2017
Citation:
Zhou, B., Luo, Y., Bauchan, G., Feng, H., and Stommel, J. 2017.Visualizing Pathogen Internalization Pathways in Fresh Tomatoes Using a Confocal Laser Scanning Microscope and a Micro CT. Poster presentation, International Association of Food Protection Annual Meeting, Tampa, FL.
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