Source: EASTERN REGIONAL RES CENTER submitted to
INTEGRATION OF MULTIPLE INTERVENTIONS TO ENHANCE MICROBIAL SAFETY, QUALITY, AND SHELF-LIFE OF FOODS
Sponsoring Institution
Agricultural Research Service/USDA
Project Status
NEW
Funding Source
Reporting Frequency
Annual
Accession No.
0430393
Grant No.
(N/A)
Project No.
8072-41000-101-00D
Proposal No.
(N/A)
Multistate No.
(N/A)
Program Code
(N/A)
Project Start Date
Feb 10, 2016
Project End Date
Feb 9, 2021
Grant Year
(N/A)
Project Director
FAN X
Recipient Organization
EASTERN REGIONAL RES CENTER
(N/A)
WYNDMOOR,PA 19118
Performing Department
(N/A)
Non Technical Summary
(N/A)
Animal Health Component
(N/A)
Research Effort Categories
Basic
10%
Applied
60%
Developmental
30%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2041219106010%
5011420110010%
5021440202010%
7121099106010%
2041110110010%
5011199202010%
5021430106020%
7121460110010%
2041499202010%
Goals / Objectives
This project will focus on the integration of effective intervention technologies and treatments to enhance microbial safety of fresh fruits and vegetables with a holistic approach addressing major elements (safety, quality, and shelf-life), necessary for the implementation of technologies. The ultimate goal is to reduce the risk of foodborne illnesses associated with consumption of fresh produce, while maintaining acceptable food quality and shelf-life. Specific objectives of the research program are: Objective 1 - Develop and optimize single intervention technologies to reduce pathogen populations, maintain quality, and extend shelf-life of foods. Sub-objective 1.1. Develop and optimize aerosolizing technology and pulsed light to reduce pathogen populations, maintain sensorial and nutritional quality, and extend shelf-life of fresh produce. Sub-objective 1.2. Develop new antimicrobial packaging/coating-based technologies by incorporating natural, modified and novel materials to inactivate foodborne pathogens on fresh produce. Objective 2 - Determine the synergistic/additive effectiveness of combining non-thermal processing, antimicrobial packaging and effective chemical interventions utilizing information generated from the first objective.
Project Methods
An integrated approach to enhance microbial safety while maintaining product quality and extending shelf life of fresh produce will be adopted by combining aerosolizing antimicrobials, pulsed light antimicrobial packaging and other interventions. The types of fresh and fresh-cut produce evaluated in the project will be those frequently involved in outbreaks of foodborne illnesses, those that are hard to sanitize due to surface characteristics, and those that cannot be washed. During the first part of the proposed project plan, we will develop and optimize new aerosolization systems, pulsed light technology, novel antimicrobial coating with incorporation of nature and bio-based substances, and antimicrobial packaging materials with controlled-release mechanisms triggered with either acids or pulsed light. The optimized/developed interventions and antimicrobial packaging will then be combined with each other, and with other effective antimicrobial treatments to study the synergistic or additive effects on pathogen inactivation while maintaining quality and shelf-life of fresh produce. When selecting combinations, technologies with different pathogen-inactivation mechanisms or synergistic interactions will be desirable. We will utilize the advanced oxidation, photochemical, and photothermal, and triggered-release mechanisms and other hurdle technologies to increase the efficacy of combined antimicrobial treatments. By combining effective intervention technologies and treatments, synergistic effects with a targeted 5-log reduction of common pathogens may be achieved. Pathogens to be included in the proposed project plan are Salmonella spp., E. coli O157:H7, L. monocytogenes and other emerging pathogens (such as non-O157 STECs). We will use a representative cocktail of 3-5 strains from each genera of bacteria that are associated with outbreaks of relevant fresh produce. Scientifically well-established inoculation, recovery, and enumeration procedures will be used. Appropriate controls will be included in each experiment, and experiments will be replicated independently at least three times. Inoculation of fresh produce will be achieved either by surface ¿spot inoculation¿ where specific locations on the produce surface will be inoculated or by a ¿dip inoculation¿ technique where the whole produce item will be submerged in the experimental inocula. The inoculated fresh produce will be drained and air dried in a laminar flow hood before being subjected to various treatments. After treatment with various chemicals and physical interventions, the total number of viable and injured bacteria will be determined using amended media. The effects of the individual and combined treatments on the physiochemical and sensorial quality and shelf-life will be evaluated during storage. Shelf-life will be determined based on the deterioration in product quality and increasing populations of microorganisms that render the product unacceptable to consumers.

Progress 10/01/19 to 09/30/20

Outputs
Progress Report Objectives (from AD-416): This project will focus on the integration of effective intervention technologies and treatments to enhance microbial safety of fresh fruits and vegetables with a holistic approach addressing major elements (safety, quality, and shelf-life), necessary for the implementation of technologies. The ultimate goal is to reduce the risk of foodborne illnesses associated with consumption of fresh produce, while maintaining acceptable food quality and shelf-life. Specific objectives of the research program are: Objective 1 - Develop and optimize single intervention technologies to reduce pathogen populations, maintain quality, and extend shelf-life of foods. Sub-objective 1.1. Develop and optimize aerosolizing technology and pulsed light to reduce pathogen populations, maintain sensorial and nutritional quality, and extend shelf-life of fresh produce. Sub-objective 1.2. Develop new antimicrobial packaging/coating-based technologies by incorporating natural, modified and novel materials to inactivate foodborne pathogens on fresh produce. Objective 2 - Determine the synergistic/additive effectiveness of combining non-thermal processing, antimicrobial packaging and effective chemical interventions utilizing information generated from the first objective. Approach (from AD-416): An integrated approach to enhance microbial safety while maintaining product quality and extending shelf life of fresh produce will be adopted by combining aerosolizing antimicrobials, pulsed light antimicrobial packaging and other interventions. The types of fresh and fresh-cut produce evaluated in the project will be those frequently involved in outbreaks of foodborne illnesses, those that are hard to sanitize due to surface characteristics, and those that cannot be washed. During the first part of the proposed project plan, we will develop and optimize new aerosolization systems, pulsed light technology, novel antimicrobial coating with incorporation of nature and bio-based substances, and antimicrobial packaging materials with controlled-release mechanisms triggered with either acids or pulsed light. The optimized/developed interventions and antimicrobial packaging will then be combined with each other, and with other effective antimicrobial treatments to study the synergistic or additive effects on pathogen inactivation while maintaining quality and shelf-life of fresh produce. When selecting combinations, technologies with different pathogen-inactivation mechanisms or synergistic interactions will be desirable. We will utilize the advanced oxidation, photochemical, and photothermal, and triggered- release mechanisms and other hurdle technologies to increase the efficacy of combined antimicrobial treatments. By combining effective intervention technologies and treatments, synergistic effects with a targeted 5-log reduction of common pathogens may be achieved. Pathogens to be included in the proposed project plan are Salmonella spp., E. coli O157:H7, L. monocytogenes and other emerging pathogens (such as non-O157 STECs). We will use a representative cocktail of 3-5 strains from each genera of bacteria that are associated with outbreaks of relevant fresh produce. Scientifically well-established inoculation, recovery, and enumeration procedures will be used. Appropriate controls will be included in each experiment, and experiments will be replicated independently at least three times. Inoculation of fresh produce will be achieved either by surface ⿿spot inoculation⿿ where specific locations on the produce surface will be inoculated or by a ⿿dip inoculation⿿ technique where the whole produce item will be submerged in the experimental inocula. The inoculated fresh produce will be drained and air dried in a laminar flow hood before being subjected to various treatments. After treatment with various chemicals and physical interventions, the total number of viable and injured bacteria will be determined using amended media. The effects of the individual and combined treatments on the physiochemical and sensorial quality and shelf-life will be evaluated during storage. Shelf- life will be determined based on the deterioration in product quality and increasing populations of microorganisms that render the product unacceptable to consumers. Progress was made on Objective 2, which falls under National Program 108, Component I, Foodborne Contaminants, and National Action Plan Problem Statement 5, Intervention and Control Strategies. Experiments were conducted to develop formulations for the inactivation of Listeria monocytogenes while maintaining freshness of cut apples, and employ advanced oxidation processes by combining titanium dioxide (TiO2)-based antimicrobial packaging systems with pulsed light, and integrating pulsed light technology with aqueous sanitizers to achieve synergistic or additive reductions of human pathogens and spoilage microorganisms while maintaining quality of fresh produce. Two patent applications have been filed relating to the development of novel bio-based antimicrobials. Due to the COVID-19 pandemic, not all milestone projects are fully completed. Detailed progress to achieve the overall objectives is listed below. A number of natural and bio-based antimicrobials were screened either individually or in combinations for their efficacy in inactivating a cocktail of Listeria monocytogenes. Furthermore, those showing anti- listerial activity were applied onto cut apples to evaluate their ability in inhibiting surface browning of the fruits, while maintaining firmness. Results showed some combinations were able to achieve more than 99.999% reductions of the pathogen while preserving the freshness of cut-fruit. Research continues to optimize the formulations and assess shelf-life of treated cut fruits. Experiments were conducted to develop antimicrobial packaging films containing nano scale TiO2. Polylactic acid (PLA)-TiO2 antimicrobial films were produced using a solvent cast method by mixing PLA powder with TiO2 nano particles. The antimicrobial activity of the film was activated by normal fluorescent light and enhanced by pulsed light. The populations of Listeria and E. coli on PLA-TiO2 antimicrobial films were reduced by 96% and 98.5% under normal light conditions, respectively, while pulsed light for 5 seconds achieved over 99.9% reduction of the bacteria. Light- activated PLA-TiO2 antimicrobial films maintained antibacterial activity and had lower bacterial populations than that without light-activated films. The results demonstrate that the developed antimicrobial packaging material can be used to fabricate food containers or packaging films with pathogen-free surface. Further studies will be conducted with real food. Experiments were also conducted to develop and validate a method using low dose/short duration pulsed light (PL) in presence of hydrogen peroxide (H2O2) (1-3%) and in presence or absence of TiO2 to investigate the efficacy of advanced oxidation process (AOP). In the AOP treatment, PL interacts with H2O2 and TiO2, creating highly reactive hydroxyl radicals possessing strong oxidizing capability to inactivate pathogens and other microorganisms on the surfaces of produce. In a laboratory scale study, a brief 30 s pulsed light treatment with 3% H2O2 provided a 99.9% reduction of a three serotype Salmonella composite inoculated on blueberries. Effectiveness of inactivation was increased to 99.99% when TiO2 (10 ppm) was added to the system. No difference in decontamination efficacy was observed between 30 s and 60 s PL/H2O2 treatments. The AOP treatment also reduced native microbial populations on blueberries and slowed their growth during storage. Overall, results demonstrate that PL/ H2O2 integrated AOP technology can be used to enhance microbial safety of produce. Accomplishments 01 Combining cold plasma and hydrogen peroxide enhances the microbial safety of fruits. ARS scientists at Wyndmoor, Pennsylvania, combined cold plasma and hydrogen peroxide aerosols to produce highly reactive radicals that reduced the populations of bacteria on fresh fruits. Applying cold plasma to hydrogen peroxide increased the effectiveness of hydrogen peroxide aerosols, and killed almost 100 percent of Salmonella and Listeria on surfaces of apples, cantaloupe, and tomatoes. This new process did not affect appearance, color, texture or nutritional quality of the produce. These results would be of interest to produce industry seeking to enhance the microbial safety while keeping the fruits fresh longer. ARS scientists are collaborating with industry partners to explore the commercial applicability of the technology. 02 Pulsed light and Nisin-based sanitizer combination treatment can assure microbial safety of produce. Currently, produce industry employs chlorine-based sanitizers to reduce cross contamination despite issues related to their safety and effectiveness. Hence, there is a need to develop chlorine-free decontamination technologies. Researchers at Wyndmoor, Pennsylvania, developed a safe and effective method combining pulsed light with a Nisin-based sanitizer. This combined treatment method of pulsed light and the Nisin-based sanitizer, exhibited a synergistic activity killing almost one hundred percent of pathogens like Salmonella in tomatoes. The combination treatment is also proven effective in protecting sensory qualities like visual appearance and firmness of tomatoes. This new combined treatment can be used as a replacement for current chlorine-based sanitizers wash in the tomato industry. 03 Application of essential oil washing and vapor treatments for food safety and shelf life. Fresh blackberries are a nutritious fruit, but they have a short shelf life and are contaminated easily by pathogenic spoilage microorganisms. ARS scientists at Wyndmoor, Pennsylvania, investigated methods to reduce microbial contaminants on blackberries using essential oil wash, vapor, and their combination. The combination of essential oil wash and vapor treatments completely inhibited the growth of bacteria and fungi and extended the shelf life of fresh blackberries from 5 days to over 12 days at cool temperatures (10 degrees centigrade). The study shows that the essential oil treatment is good for maintaining the microbiological and nutritional qualities and extending the shelf life of blackberries.

Impacts
(N/A)

Publications

  • Leng, J., Mukhopadhyay, S., Sokorai, K., Ukuku, D.O., Fan, X., Olanya, O.M. , Juneja, V.K. 2019. Inactivation of Salmonella in cherry tomato stems cars and quality preservation by pulsed light treatment and antimicrobial wash. Food Control. 110:107005.
  • Fan, X., Sokorai, K., Gurtler, J. 2019. Advanced oxidation process for the inactivation of Salmonella Typhimurium on tomatoes by combination of gaseous ozone and aerosolized hydrogen peroxide. International Journal of Food Microbiology. 312.
  • Wang, L., Fan, X., Gurtler, J., Wang, W. 2019. Interaction of gaseous chlorine dioxide and mild heat on the inactivation of Salmonella on almonds. Journal of Food Protection. 82(10):1729⿿1735.
  • Song, Y., Fan, X. 2019. Cold plasma enhances the efficacy of aerosolized hydrogen peroxide in reducing populations of Salmonella Typhimurium and Listeria innocua on grape tomatoes, apples, cantaloupe and romaine lettuce. Food Microbiology.
  • Song, Y., Annous, B.A., Fan, X. 2020. Cold plasma-activated hydrogen peroxide aerosol on populations of Salmonella Typhimurium and Listeria innocua and quality changes of apple, tomato and cantaloupe during storage - a pilot scale study. Food Control. 117.
  • Wang, W., Li, X., Du, M., Fan, X., Zhao, J., Cao, R. 2019. Improvement in the oxidative stability of flaxseed oil using an edible guar gum-tannic acid nanofibrous mat. European Journal of Lipid Science and Technology.
  • Zhou, S., Jin, Z.T., Sheen, S., Zhao, G., Liu, L.S., Juneja, V.K., Yam, K. 2020. Development of sodium chlorite and glucono delta-lactone incorporated PLA film for microbial inactivaton on fresh tomato. Food Research International. 132:1-7.
  • Gurtler, J., Keller, S.E., Fan, X., Olanya, O.M., Jin, Z.T., Camp, M.J. 2019. Survival of Salmonella during apple dehydration as affected by apple cultivar and antimicrobial pretreatment. Journal of Food Protection. 82(4) :628-644.
  • Jin, Z.T., Chen, W., Gurtler, J., Fan, X. 2020. Effectiveness of edible coatings to inhibit browning and inactivate foodborne pathogens on fresh- cut apples. Journal of Agricultural and Food Chemistry.
  • Oliverira, G.M., Jin, Z.T., Campanella, O.H. 2020. Modeling the inactivation of escherichia coli O157:H7 and salmonella typhimurium in juices by pulsed electric fields: The role of the energy density. Journal of Food Process Engineering.
  • Wang, L., Fan, X., Sokorai, K.J., Sites, J.E. 2019. Quality deterioration of grape tomato fruit during storage after treatments with gaseous ozone at conditions that significantly reduced populations of Salmonella on stem scar and smooth surface. Food Control. 103:9-20.
  • Yu, Y., Jin, Z.T., Fan, X., Gurtler, J. 2019. Effects of carvacrol wash and ally isothiocyanate vapor treatment to extend the shelf life of blackberries. Jacobs Journal of Food and Nutrition. 6(4):46-57.


Progress 10/01/18 to 09/30/19

Outputs
Progress Report Objectives (from AD-416): This project will focus on the integration of effective intervention technologies and treatments to enhance microbial safety of fresh fruits and vegetables with a holistic approach addressing major elements (safety, quality, and shelf-life), necessary for the implementation of technologies. The ultimate goal is to reduce the risk of foodborne illnesses associated with consumption of fresh produce, while maintaining acceptable food quality and shelf-life. Specific objectives of the research program are: Objective 1 - Develop and optimize single intervention technologies to reduce pathogen populations, maintain quality, and extend shelf-life of foods. Sub-objective 1.1. Develop and optimize aerosolizing technology and pulsed light to reduce pathogen populations, maintain sensorial and nutritional quality, and extend shelf-life of fresh produce. Sub-objective 1.2. Develop new antimicrobial packaging/coating-based technologies by incorporating natural, modified and novel materials to inactivate foodborne pathogens on fresh produce. Objective 2 - Determine the synergistic/additive effectiveness of combining non-thermal processing, antimicrobial packaging and effective chemical interventions utilizing information generated from the first objective. Approach (from AD-416): An integrated approach to enhance microbial safety while maintaining product quality and extending shelf life of fresh produce will be adopted by combining aerosolizing antimicrobials, pulsed light antimicrobial packaging and other interventions. The types of fresh and fresh-cut produce evaluated in the project will be those frequently involved in outbreaks of foodborne illnesses, those that are hard to sanitize due to surface characteristics, and those that cannot be washed. During the first part of the proposed project plan, we will develop and optimize new aerosolization systems, pulsed light technology, novel antimicrobial coating with incorporation of nature and bio-based substances, and antimicrobial packaging materials with controlled-release mechanisms triggered with either acids or pulsed light. The optimized/developed interventions and antimicrobial packaging will then be combined with each other, and with other effective antimicrobial treatments to study the synergistic or additive effects on pathogen inactivation while maintaining quality and shelf-life of fresh produce. When selecting combinations, technologies with different pathogen-inactivation mechanisms or synergistic interactions will be desirable. We will utilize the advanced oxidation, photochemical, and photothermal, and triggered- release mechanisms and other hurdle technologies to increase the efficacy of combined antimicrobial treatments. By combining effective intervention technologies and treatments, synergistic effects with a targeted 5-log reduction of common pathogens may be achieved. Pathogens to be included in the proposed project plan are Salmonella spp., E. coli O157:H7, L. monocytogenes and other emerging pathogens (such as non-O157 STECs). We will use a representative cocktail of 3-5 strains from each genera of bacteria that are associated with outbreaks of relevant fresh produce. Scientifically well-established inoculation, recovery, and enumeration procedures will be used. Appropriate controls will be included in each experiment, and experiments will be replicated independently at least three times. Inoculation of fresh produce will be achieved either by surface ⿿spot inoculation⿿ where specific locations on the produce surface will be inoculated or by a ⿿dip inoculation⿿ technique where the whole produce item will be submerged in the experimental inocula. The inoculated fresh produce will be drained and air dried in a laminar flow hood before being subjected to various treatments. After treatment with various chemicals and physical interventions, the total number of viable and injured bacteria will be determined using amended media. The effects of the individual and combined treatments on the physiochemical and sensorial quality and shelf-life will be evaluated during storage. Shelf- life will be determined based on the deterioration in product quality and increasing populations of microorganisms that render the product unacceptable to consumers. Progress was made on Objective 2, which falls under National Program 108, Component I, Foodborne Contaminants, and National Action Plan Problem Statement 5, Intervention and Control Strategies. Experiments were conducted to determine the synergistic/additive effectiveness of combining pulsed light, antimicrobial packaging, and aerosolized/ vaporized antimicrobials to maximize the effectiveness of the interventions against various human pathogens and spoilage microorganisms while maintaining sensory quality of fresh produce. Detailed progress to achieve the overall objective is listed below. Experiments were conducted to develop and validate a method using low dose/short duration pulsed light followed by aerosolized antimicrobial treatment for greater than 3 logs reductions of common food-borne pathogens in fresh leafy greens and tomato fruits without significant quality deterioration. Among various aerosolized antimicrobials tested, aerosolized formulations containing hydrogen peroxide and organic acids exhibited significant synergistic effects with pulsed light, inactivating > 99.999% of Salmonella and E. coli O157:H7 on tomato and romaine lettuce. The pulsed light - aerosolized sanitizer combination provided not only a pasteurizing effect, but also reduced native microbial populations on these produces and slowed their growth during storage. Furthermore, the color parameters and the firmness of the produce were not significantly affected by the combination of treatments. Overall, results demonstrate that the integrated pulsed light - aerosolized sanitizer treatment technology can be used to enhance microbial safety of produce. Findings from this research will greatly benefit the farmers and small to large produce industries. Progress was made by combining natural antimicrobials aerosolized into packages of fresh produce in which gaseous chlorine dioxide-releasing film was included. The aerosolized antimicrobials not only inactivated pathogenic microorganisms by themselves, but also helped in facilitating the release of gaseous chlorine dioxide from the films into the headspace of packages. As a result, higher reductions of pathogens such as Salmonella on berries and lettuce were achieved than the individual treatment alone. Further studies will be conducted to improve repeatability of the treatments, and evaluate the impact of these treatments on the quality of treated food products. Packaging films releasing gaseous antimicrobials into headspace of packaging containers were continuously studied. Films with biopolymers and carvacrol, an essential oil component, were placed on the lid of food containers and their antimicrobial efficacy against foodborne pathogens (Listeria and E. coli) and spoilage microorganisms in cherry tomatoes was investigated. Results show that these antimicrobial films placed inside of food containers effectively killed or inhibited the growth of pathogens and spoilage microorganisms. Further studies will be conducted to evaluate the impact of these treatments on the quality of treated foods. In addition, significant progress has been made on a NIFA-funded project involving inactivation of Salmonella and quality maintenance of low moisture foods treated with gaseous chlorine dioxide. Result showed that Salmonella populations can be reduced by more than 99.99% with gaseous chlorine dioxide treatments, when combined with mild heating and high relative humidity. Studies on possible formation of chlorine-containing byproducts are underway. Furthermore, in collaboration with an industry partner, the impact of cold plasma on the effectiveness of aerosolized hydrogen peroxide was evaluated. Results showed that cold plasma activated the hydrogen peroxide aerosols and significantly increased the inactivation effectiveness of hydrogen peroxide against Salmonella and Listeria on a number of fresh produce items. Accomplishments 01 Integrated interventions of processing and coating can provide microbial food safety. Currently the produce industry employs chlorine to avoid cross contamination during processing despite its limited ability to reduce pathogens, and potential of forming possible carcinogenic chlorine by-products in wash water. Hence, there is a need to develop chlorine-free decontamination technologies. Researchers at Wyndmoor, Pennsylvania developed a safe and effective produce safety method combining pulsed light treatment with a sanitizer wash. In a laboratory scale study, this integrated technology inactivated > 99. 999% of pathogens such as E. coli O157:H7 in spinach. This combination treatment was also effective in controlling native microbial loads during 21 days of refrigerated storage. Furthermore, firmness and the visual appearance of spinach were not affected by the treatment. Pulsed light is an FDA approved technology while all components of the sanitizer are generally recognized safe compounds. This new integrated method of pulsed light treatment with this new formula sanitizer wash can be used as a replacement for current chlorine-based industrial practice. 02 Mild heating and gaseous chlorine dioxide enhances microbial safety of almonds. Salmonella outbreaks have been linked to the consumption of raw almonds. As a result, USDA and Almond Board of California mandated pasteurization of almonds with a minimal 99.99% Salmonella reduction. Currently, almonds are mostly treated with propylene oxide, however there is a safety concern over the use of propylene oxide. Therefore, other intervention technologies are necessary in achieving the mandatory goal of the 99.99% reduction. ARS scientists in Wyndmoor, Pennsylvania evaluated the combination of gaseous chlorine dioxide and mild heating in inactivating Salmonella on almonds. Results demonstrated that applying gaseous chlorine dioxide at 55 degree Celsius achieved more than 99.99% reductions of Salmonella on almonds. The study established the condition of chlorine dioxide needed to meet mandatory goal of almond pasteurization. 03 Combination of antimicrobial packaging and sanitizer solution improves food safety and quality. Fresh strawberries have a short shelf life and were associated with foodborne outbreaks. ARS scientists at Wyndmoor, Pennsylvania evaluated the effectiveness of antimicrobial wash and coating treatments, either individually or in combination, in reducing populations of E. coli O157:H7 and Salmonella on strawberries. The combination treatments reduced over 99% of pathogens and native microflora. Both the combination and the antimicrobial coating treatments preserved the color, texture, and appearance of strawberries throughout 3 weeks storage at 4 degree Celsius. The combined method has the potential to improve the microbiological safety, shelf-life, and quality of strawberries. 04 Gaseous chlorine dioxide inactivates Salmonella while maintaining quality of tomatoes. There have been a number of reports on the effectiveness of gaseous chlorine dioxide in inactivating various human pathogens associated with fresh produce. However, studies dealing with both microbial reduction and impact on quality and nutrients of tomatoes are scarce. ARS scientists in Wyndmoor, Pennsylvania determined the efficacy of gaseous chlorine dioxide in inactivating Salmonella, and the impact on sensory and nutritional quality of grape tomatoes. Results demonstrated that gaseous chlorine dioxide that reduced populations of Salmonella by 99.99% on tomatoes did not significantly affect appearance, texture, color, odor, or lycopene and ascorbic acid contents of tomatoes. The study eases concern over damage of the fruit caused by gaseous chlorine dioxide, and may help in facilitating the commercial applications of the gaseous antimicrobial on fresh produce.

Impacts
(N/A)

Publications

  • Mukhopadhyay, S., Sokorai, K.J., Ukuku, D.O., Fan, X., Olanya, O.M., Juneja, V.K. 2019. Effects of pulsed light and sanitizer wash combination on inactivation of Escherichia coli 0157:H7, microbial loads and apparent quality of spinach leaves. Food Microbiology. 82:127-134.
  • Guo, M., Jin, Z.T., Gurtler, J., Fan, X., Yadav, M.P. 2018. Inactivation of E.coli O157:H7 and Salmonella on fresh strawberries by antimicrobial washing and coating. Journal of Food Protection. 81(8):1227-1235.
  • Gurtler, J., Fan, X., Jin, Z.T., Niemira, B.A. 2019. Effects of antimicrobials on the thermal sensitivity of foodborne pathogens: A review. Journal of Food Protection. 82(4):628-644.
  • Gao, H., Fan, X., Chen, H., Qin, Y., Wu, W., Jin, Z.T. 2018. Microbial inactivation and quality improvement of tomatoes treated by package film with Allyl Isothiocyanate vapor. International Journal of Food Science and Technology. 53:1983-1991.
  • Min, S.C., Roh, S., Niemira, B.A., Boyd, G., Sites, J.E., Fan, X., Sokorai, K.J., Jin, Z.T. 2018. In-Package atmospheric cold plasma treatment of bulk grape tomatoes for their microbiological safety and preservation. 108:378-386.


Progress 10/01/17 to 09/30/18

Outputs
Progress Report Objectives (from AD-416): This project will focus on the integration of effective intervention technologies and treatments to enhance microbial safety of fresh fruits and vegetables with a holistic approach addressing major elements (safety, quality, and shelf-life), necessary for the implementation of technologies. The ultimate goal is to reduce the risk of foodborne illnesses associated with consumption of fresh produce, while maintaining acceptable food quality and shelf-life. Specific objectives of the research program are: Objective 1 - Develop and optimize single intervention technologies to reduce pathogen populations, maintain quality, and extend shelf-life of foods. Sub-objective 1.1. Develop and optimize aerosolizing technology and pulsed light to reduce pathogen populations, maintain sensorial and nutritional quality, and extend shelf-life of fresh produce. Sub-objective 1.2. Develop new antimicrobial packaging/coating-based technologies by incorporating natural, modified and novel materials to inactivate foodborne pathogens on fresh produce. Objective 2 - Determine the synergistic/additive effectiveness of combining non-thermal processing, antimicrobial packaging and effective chemical interventions utilizing information generated from the first objective. Approach (from AD-416): An integrated approach to enhance microbial safety while maintaining product quality and extending shelf life of fresh produce will be adopted by combining aerosolizing antimicrobials, pulsed light antimicrobial packaging and other interventions. The types of fresh and fresh-cut produce evaluated in the project will be those frequently involved in outbreaks of foodborne illnesses, those that are hard to sanitize due to surface characteristics, and those that cannot be washed. During the first part of the proposed project plan, we will develop and optimize new aerosolization systems, pulsed light technology, novel antimicrobial coating with incorporation of nature and bio-based substances, and antimicrobial packaging materials with controlled-release mechanisms triggered with either acids or pulsed light. The optimized/developed interventions and antimicrobial packaging will then be combined with each other, and with other effective antimicrobial treatments to study the synergistic or additive effects on pathogen inactivation while maintaining quality and shelf-life of fresh produce. When selecting combinations, technologies with different pathogen-inactivation mechanisms or synergistic interactions will be desirable. We will utilize the advanced oxidation, photochemical, and photothermal, and triggered- release mechanisms and other hurdle technologies to increase the efficacy of combined antimicrobial treatments. By combining effective intervention technologies and treatments, synergistic effects with a targeted 5-log reduction of common pathogens may be achieved. Pathogens to be included in the proposed project plan are Salmonella spp., E. coli O157:H7, L. monocytogenes and other emerging pathogens (such as non-O157 STECs). We will use a representative cocktail of 3-5 strains from each genera of bacteria that are associated with outbreaks of relevant fresh produce. Scientifically well-established inoculation, recovery, and enumeration procedures will be used. Appropriate controls will be included in each experiment, and experiments will be replicated independently at least three times. Inoculation of fresh produce will be achieved either by surface �spot inoculation� where specific locations on the produce surface will be inoculated or by a �dip inoculation� technique where the whole produce item will be submerged in the experimental inocula. The inoculated fresh produce will be drained and air dried in a laminar flow hood before being subjected to various treatments. After treatment with various chemicals and physical interventions, the total number of viable and injured bacteria will be determined using amended media. The effects of the individual and combined treatments on the physiochemical and sensorial quality and shelf-life will be evaluated during storage. Shelf- life will be determined based on the deterioration in product quality and increasing populations of microorganisms that render the product unacceptable to consumers. Progress was made on Objectives 1 and 2, which fall under National Program 108, Component I, Foodborne Contaminants, and National Action Plan Problem Statement 5, Intervention and Control Strategies. Experiments were conducted to develop antimicrobial films that release chlorine dioxide gas, integrate sanitizer washes with pulsed light, and combine aerosolized hydrogen peroxide with gaseous ozone in order to maximize the effectiveness in inactivating various human pathogens and spoilage microorganisms while maintaining sensory quality of fresh produce. Detailed progress to achieve the overall objectives is listed below. Under Objective 1, significant progress was made by continuous development and evaluation of antimicrobial films that release gaseous chlorine dioxide into the headspace of packaging containers. The concentration of sodium chlorite (a chlorine dioxide precursor) in the films and the methods to make the films (press, coating, etc.) were evaluated for their antimicrobial efficacy against foodborne pathogens (Listeria, Salmonella, and E. coli) and spoilage microorganisms in growth media, broccoli, strawberries and tomatoes. Results show that these antimicrobial films placed inside of food containers effectively killed or inhibited the growth of pathogens and spoilage microorganisms. Further studies will be conducted to evaluate the impact of these treatments on the quality of treated foods. Under Objective 2, experiments were conducted to develop and validate a method using pulsed light followed by sanitizer washing for greater than 3 log reductions of common food borne pathogens in fresh leafy green and tomato fruits without significant quality deterioration. Among various sanitizers tested, hydrogen peroxide + EDTA + nisin, and organic acid + EDTA + nisin exhibited synergistic effects with pulsed light, inactivating more than 99.999% of Salmonella and E. coli O157:H7 on tomato and spinach leaves, respectively. In addition, the treatments also reduced initial native microbial populations on these produces and slowed their growth during storage. Furthermore, color and firmness of the produce were not significantly affected by the combination treatment method. Overall, results demonstrate that the integrated pulsed light- sanitizer technology can be used to enhance microbial safety of produce. Also under Objective 2, significant progress was made by an advanced oxidation process which combined aerosolized hydrogen peroxide and gaseous ozone to inactivate Salmonella Typhimurium on tomato fruits. Tomatoes inoculated with a cocktail of Salmonella Typhimurium strains on stem scar and smooth surface were treated simultaneously with combinations of gaseous ozone and hydrogen peroxide aerosolized from various concentrations of hydrogen peroxide solutions. Results showed that combinations of aerosolized hydrogen peroxide with 1,600 ppm ozone frequently reduced the populations of Salmonella by 99.999% on the smooth surface of the fruit. On the stem scar area, combinations of 1,600 ppm ozone and aerosolized hydrogen peroxide achieved 99.99% of Salmonella. Overall, our results suggest that the advanced oxidation process with combinations of hydrogen peroxide and gaseous ozone may be used to inactivate Salmonella on tomato fruits. Studies are underway to evaluate quality of fruits treated with the process. In addition, significant progress has been made on a NIFA-funded project involving applying gaseous antimicrobials to inactivate Salmonella on tomato fruit. Gaseous chlorine dioxide and ozone were evaluated for its effectiveness on reducing populations of Salmonella and native microorganisms on grape tomatoes, and impacts on sensory and nutritional quality. Results showed that chlorine dioxide at headspace concentration of 4.3 mg per liter reduced Salmonella populations by more than 99.99%. The treatments did not have any significant effect on appearance, off- odor, firmness, color, lycopene, or vitamin C contents of grape tomatoes during the 21 days storage at 10�C. While dry ozone was capable of reducing Salmonella populations by 99%, the treatment significantly reduced firmness and decreased lycopene and vitamin C contents of the fruit. Overall, our results showed gaseous chlorine dioxide preserved the sensory or nutritional quality of tomatoes while dry ozone did not. Studies are underway to investigate the effects of humidified ozone on Salmonella populations and quality of the fruit. Furthermore, pulsed electric field technology was used to inactivate foodborne pathogens and spoilage microorganisms in special formulated heath juices. Preliminary results show that 5 log reduction of E. coli O157:H7 can be achieved by adjusting pulsed electric field treatment parameters. More studies will be conducted to evaluate the quality and shelf life of treated foods. Accomplishments 01 Novel antibrowning and antimicrobial formulation for cut apples. There have been a number of recalls of cut apples due to contamination with Listeria monocytogenes. Therefore, there is an urgent need to develop antimicrobial formulations to minimize the risk of Listeria contamination while maintaining the freshness of cut apples. ARS scientists at Wyndmoor, Pennsylvania systemically evaluated the combinations of organic acids and various antioxidants for their anti- listerial and anti-browning properties. Results showed that formulations comprised of citric acid (a fruit acid), ascorbic acid (vitamin C), and N-acetyl-L-cysteine (an amino acid) were able to reduce populations of L. monocytogenes by more than 99.999% and at the same time, inhibited the surface browning of cut apples for at least 21 days. The developed formulations, if adopted by the fresh produce industry, may reduce the risk of Listeria contamination and maintain shelf life of cut apples. 02 Antimicrobial films used for in-package pasteurization. Foodborne pathogens and spoilage fungi may reside in fresh produce after packaging. ARS scientists at Wyndmoor, Pennsylvania developed antimicrobial films that released allyl isothiocyanate vapor (a natural flavor compound from mustard) into headspace of the container and inhibited E. coli and fungi growth in fresh tomatoes stored at 4 and 10 �C for 21 days. The treatment reduced the populations of bacteria and molds by 99 - 99.9% on tomatoes, and treated fruit had less change in quality and nutritional values during storage than the non-treated samples. The developed antimicrobial film has the potential to enhance the safety and extend the shelf-life of perishable fresh produce. 03 Integrated interventions of processing and coating improve microbial food safety. Currently, the produce industry employs chlorine to avoid cross contamination despite its limited ability to eliminate pathogens and to form potentially carcinogenic chlorine by-products in wash water. Hence, there is a need to develop new chlorine-free decontamination technologies. ARS scientists at Wyndmoor, Pennsylvania developed a safe and effective method combining organic acid wash with chitosan-allyl isothiocyanate (natural compounds with broad antimicrobial properties) antimicrobial coating. This integrated technology inactivated more than 99.999% of Salmonella on tomatoes. The treatment was also effective in controlling native microbial loads during storage. Furthermore, the firmness and color of tomatoes were not affected by the treatments. This new integrated method potentially can be used as a replacement for current chlorine-based sanitizers. 04 Enhancing tomato safety with organic acids. Consumption of raw tomatoes has been implicated in multiple Salmonella outbreaks in the U. S. ARS researchers have previously shown that washing round tomatoes with combinations of organic acids reduced populations of Salmonella by 99.999%. However, the impact of the acid washes on fruit quality and factors that influence their efficacy have not been studied. ARS scientists at Wyndmoor, Pennsylvania evaluated the changes in fruit quality after acid washes and compared two types of common tomatoes in response to the treatments. Results demonstrated that the treatments were more effective in reducing populations of Salmonella on large round tomatoes than on small grape tomatoes, and the water rinse after acid treatments negated residual acidic odor caused by the acid wash treatments. The information will help the produce industry in adopting more effective treatments to enhance the microbial safety of tomatoes while maintaining fruit quality.

Impacts
(N/A)

Publications

  • Fan, X., Huang, R., Chen, H. 2017. Application of ultraviolet C technology for surface decontamination of fresh produce. Current Opinion in Food Science. 70:9-19.
  • Mukhopadhyay, S., Ukuku, D.O., Juneja, V.K., Nayak, B., Olanya, O.M. 2018. Microbial control and food Preservation: Theory and practice: Principles of food preservation. Book Chapter.
  • Guo, M., Yadav, M.P., Jin, Z.T. 2017. Antimicrobial edible coatings and films from micro-emulsions and their food applications. Food Control. 263:9-16.
  • Mukhopadhyay, S., Sokorai, K.J., Ukuku, D.O., Jin, Z.T., Fan, X., Olanya, O.M., Juneja, V.K. 2018. Inactivation of Salmonella in tomato stem scars by organic acid wash and chitosan-allyl isothiocyanate coating. International Journal of Food Microbiology. 266:234-240.
  • Mukhopadhyay, S., Ukuku, D.O. 2018. The role of emerging technologies to ensure the microbial safety of fresh produce, milk and eggs. Current Opinion in Food Science.


Progress 10/01/16 to 09/30/17

Outputs
Progress Report Objectives (from AD-416): This project will focus on the integration of effective intervention technologies and treatments to enhance microbial safety of fresh fruits and vegetables with a holistic approach addressing major elements (safety, quality, and shelf-life), necessary for the implementation of technologies. The ultimate goal is to reduce the risk of foodborne illnesses associated with consumption of fresh produce, while maintaining acceptable food quality and shelf-life. Specific objectives of the research program are: Objective 1 - Develop and optimize single intervention technologies to reduce pathogen populations, maintain quality, and extend shelf-life of foods. Sub-objective 1.1. Develop and optimize aerosolizing technology and pulsed light to reduce pathogen populations, maintain sensorial and nutritional quality, and extend shelf-life of fresh produce. Sub-objective 1.2. Develop new antimicrobial packaging/coating-based technologies by incorporating natural, modified and novel materials to inactivate foodborne pathogens on fresh produce. Objective 2 - Determine the synergistic/additive effectiveness of combining non-thermal processing, antimicrobial packaging and effective chemical interventions utilizing information generated from the first objective. Approach (from AD-416): An integrated approach to enhance microbial safety while maintaining product quality and extending shelf life of fresh produce will be adopted by combining aerosolizing antimicrobials, pulsed light antimicrobial packaging and other interventions. The types of fresh and fresh-cut produce evaluated in the project will be those frequently involved in outbreaks of foodborne illnesses, those that are hard to sanitize due to surface characteristics, and those that cannot be washed. During the first part of the proposed project plan, we will develop and optimize new aerosolization systems, pulsed light technology, novel antimicrobial coating with incorporation of nature and bio-based substances, and antimicrobial packaging materials with controlled-release mechanisms triggered with either acids or pulsed light. The optimized/developed interventions and antimicrobial packaging will then be combined with each other, and with other effective antimicrobial treatments to study the synergistic or additive effects on pathogen inactivation while maintaining quality and shelf-life of fresh produce. When selecting combinations, technologies with different pathogen-inactivation mechanisms or synergistic interactions will be desirable. We will utilize the advanced oxidation, photochemical, and photothermal, and triggered- release mechanisms and other hurdle technologies to increase the efficacy of combined antimicrobial treatments. By combining effective intervention technologies and treatments, synergistic effects with a targeted 5-log reduction of common pathogens may be achieved. Pathogens to be included in the proposed project plan are Salmonella spp., E. coli O157:H7, L. monocytogenes and other emerging pathogens (such as non-O157 STECs). We will use a representative cocktail of 3-5 strains from each genera of bacteria that are associated with outbreaks of relevant fresh produce. Scientifically well-established inoculation, recovery, and enumeration procedures will be used. Appropriate controls will be included in each experiment, and experiments will be replicated independently at least three times. Inoculation of fresh produce will be achieved either by surface �spot inoculation� where specific locations on the produce surface will be inoculated or by a �dip inoculation� technique where the whole produce item will be submerged in the experimental inocula. The inoculated fresh produce will be drained and air dried in a laminar flow hood before being subjected to various treatments. After treatment with various chemicals and physical interventions, the total number of viable and injured bacteria will be determined using amended media. The effects of the individual and combined treatments on the physiochemical and sensorial quality and shelf-life will be evaluated during storage. Shelf- life will be determined based on the deterioration in product quality and increasing populations of microorganisms that render the product unacceptable to consumers. Progress was made on Objectives 1 and 2, which fall under National Program 108, Component I, Foodborne Contaminants, and National Action Plan Problem Statement 5, Intervention and Control Strategies. Experiments were conducted to optimize conditions for the applications of aerosolization and pulsed light technologies and to develop antimicrobial packaging systems. Detailed progress to achieve the overall objectives is listed below. Under objective 1, significant progress was made by optimizing aerosolization technologies for the inactivation of bacteria (Salmonella, E. coli and Listeria) inoculated onto a number of fresh produce items and for the maintenance of product quality attributes. Furthermore, a gaseous ozone treatment system with precise controlling and monitoring of ozone levels was built. The system consists of a computer controlled flow device, ozone generator, ozone analyzer, ozone destruction units, and treatment chambers. The system was tested for the inactivation of Salmonella spp. inoculated onto stem scar and smooth surface of tomatoes. Effects of gaseous ozone on product quality (appearance, color, texture etc.) are being conducted. Tests will be conducted to combine the ozone treatment with aerosolized hydrogen peroxide to produce synergistic efficacy against bacteria. Also under Objective 1, significant progress was made by applying pulsed light (PL), a non-thermal preservation method, to mitigate the safety issues associated with fresh produce. The technology uses short-duration, high-peak light pulses on food or processing/packaging surfaces. Research was conducted to optimize the pulsed light processing to achieve a minimum 3 log reductions of most common food borne pathogens such as Salmonella and E. coli O157:H7 in fresh produce without damaging the quality. Preliminary results showed pulsed light treatment was capable of inactivating greater than 99.9% of a mixed culture of Salmonella and E. coli O157:H7 inoculated on tomato stem scars and on spinach leaves. The native aerobic bacterial load was also substantially reduced, and mold and yeast population fell below the limit of detection. No visual alteration of color and texture was apparent. The result of this optimization reveals the applicability of the method for fresh produce. Under Objectives 1 and 2, significant progress was made by screening and evaluating a number of natural antimicrobials and new polymers for their antimicrobial activities against E. coli and Listeria and for film forming capacity. Furthermore, antimicrobial films, pads and cartridges that release gaseous chlorine dioxide have been developed. Preliminary results show that gaseous chlorine dioxide released from antimicrobial films, pads and cartridges placed inside of food containers is able to kill or inhibit the growth of food pathogens (Listeria, Salmonella and E. coli) and spoilage microorganisms on broccoli, strawberries and tomatoes. More studies will be conducted to evaluate the quality and shelf life of treated foods. Accomplishments 01 Aerosolized antimicrobials to enhance microbial safety of fresh produce. Washes with sanitizers such as chlorine have limited effectiveness against human pathogen on fresh produce, partially due to the inability of aqueous antimicrobials in reaching bacteria. ARS researchers at Wyndmoor, Pennsylvania aerosolized a number of FDA-approved sanitizers and activated hydrogen peroxide aerosol using cold plasma to inactivate E. coli, Salmonella and Listeria inoculated onto spinach leaves, tomato, and cantaloupe. Results showed that populations of the bacteria on the surfaces of the fresh produce items could be reduced by more than 99. 99% depending on types of inoculated bacteria and produce items. The aerosolization technology represents a novel and effective method to enhance microbial safety of fresh produce. 02 Novel edible antimicrobial coatings for the reduction of foodborne pathogens. Ready-to-eat foods, such as deli meat and fresh fruits, could be contaminated with foodborne pathogens. ARS researchers at Wyndmoor, Pennsylvania developed edible antimicrobial coating to inactivate foodborne pathogens on deli meat and fresh strawberries, using the combination of high pressure homogenization technology and bio-emulsifiers from plant byproduct. The coating treatments reduced 99% - 99.9% of foodborne pathogens (Listeria, Salmonella and Escherichia coli O157:H7) on deli meat and strawberries and hence could enhance the safety of ready-to-eat food. 03 New safety method for produce industry. The microbial safety of fresh fruits and vegetables continues to be a major concern. Fruits and vegetables frequently implicated in outbreaks include tomatoes, leafy greens and melons. Currently, the produce industry relies on washes with sanitizers such as chlorine to minimize the contamination risk. However, chlorine based chemical sanitizers have very limited effectiveness and can form potentially carcinogenic byproducts. Therefore new methods are required. ARS researchers at Wyndmoor, Pennsylvania developed a safe and effective method by integrating non- thermal UV light with a novel antimicrobial formulation developed by ARS scientists. In a laboratory scale study, this method inactivated more than 99.99% of pathogens. This new integrated method can be used as a replacement for the current chlorine-based method to ensure consumer safety. 04 Combination of non-thermal processing and sanitizer solution improves food safety and quality. Blueberry, fruit rich in nutrients, can be contaminated with pathogenic or spoilage microorganisms. ARS researchers at Wyndmoor, Pennsylvania developed a method using the combination of pulsed electric fields (PEF) and a sanitizer solution to achieve up to 99.9% reduction of E. coli and Listeria as well as 99% reduction of spoilage bacteria without causing any change in color and appearance of whole blueberries. Anthocyanins and phenolic compounds in blueberries increased by 10 and 25%, respectively, after PEF treatments. These results demonstrate the possibility of PEF to be used to enhance the safety and to improve the quality and nutritional value of fruits and derived products. 05 Packaging films releasing antimicrobial vapor. Controlled release of volatile antimicrobials exhibits more antimicrobial efficacy than their liquid phase against foodborne pathogens or spoilage bacteria in fresh produce. ARS researchers at Wyndmoor, Pennsylvania, teamed with a collaborator, developed antimicrobial polylactic acid (PLA) films releasing allyl isothiocyanate (major component in mustard oil) vapor. The antimicrobial film had more flexibility, lower gas permeability, and higher UV blocking ability than pure PLA film. The vapor released from antimicrobial films inhibited bacterial growth in fresh vegetables stored at 4 and 10 degrees C for 15 days and has the potential to be utilized for extending the shelf-life of various perishable fresh produce.

Impacts
(N/A)

Publications

  • Lew, H.N., Wagner, K., Yan, Z., Nunez, A., Yee, W.C., Fan, X., Moreau, R.A. 2017. Synthesis, chemical characterization, and economical feasibility of poly-phenolic-branched-chain fatty acids: Synthesis of poly-phenolic- branched-chain fatty acids. European Journal of Lipid Science and Technology. doi: 10.1002/ejit.201600380.
  • Fan, X., Wagner, K., Sokorai, K.J., Lew, H.N. 2017. Inactivation of gram- positive bacteria by novel phenolic branched-chain fatty acids. Journal of Food Protection. 80(1):6-14. doi: 10.4315/0362-028X.JFP-16-080.
  • Zhang, X., Ashby, R.D., Solaiman, D., Liu, Y., Fan, X. 2017. Antimicrobial activity and inactivation mechanism of lactonic and free acid sophorolipids against Escherichia coli O157:H7. Biocatalysis and Agricultural Biotechnology. 11(C):176-182. doi: 10.1016/j.bcab.2017.07. 002.
  • Fan, X., Sokorai, K.J., Weidauer, A., Gotzmann, G., Rogner, F., Koch, E. 2016. Comparison of gamma and electron beam irradiation in reducing populations of E. coli artificially inoculated on Mung Bean, clover and Fenugreek Seeds, and affecting germination and growth of seeds. Journal of Radiation Physics and Chemistry. doi: 10.1016/jradphyschem.2016.09.015.
  • Min, S.C., Roh, S., Niemira, B.A., Boyd, G., Sites, J.E., Uknalis, J., Fan, X. 2017. In-package inhibition of E.coli 0157:H7 on bulk romaine lettuce using cold plasma. Food Microbiology. 65:1-6.
  • Mukhopadhyay, S., Sokorai, K.J., Ukuku, D.O., Fan, X., Juneja, V.K. 2016. Effect of high hydrostatic pressure processing on the background microbial loads and quality of cantaloupe puree. Food Research International. doi: 10.1016/j.foodres.2016.11.029.
  • Jiang, Y., Sokorai, K.J., Pyrgiotakis, G., Demokritou, P., Li, X., Jin, Z. T., Mukhopadhyay, S., Fan, X. 2017. Cold Plasma-activated hydrogen peroxide aerosol inactivates Escherichia coli 0157:H7, Salmonella Typhimurium, and Listeria innocua and maintains quality of grape tomato, spinach and cantaloupe. International Journal of Food Microbiology. 249:53- 60.
  • Zhang, X., Ashby, R.D., Solaiman, D., Uknalis, J., Fan, X. 2016. Inactivation of Salmonella spp. and Listeria spp. by palmitic, stearic and oleic acid sophorolipids and thiamine dilauryl sulfate. Frontiers in Microbiology. doi: 10.3389/fmicb.2016.02076.
  • Yan, R., Liu, Y., Gurtler, J., Fan, X. 2017. Sensitivity of pathogenic and attenuated E. coli O157:H7 strains to ultraviolet-C light as assessed by conventional plating methods and ethidium monoazide-PCR. Journal of Food Safety. doi: 10.1111/jfs.12346.
  • Yan, R., Yun, J., Gurtler, J., Fan, X. 2017. Radiochromic film dosimetry for UV-C treatments of apple fruit. Postharvest Biology and Technology. 127:14-20.
  • Yu, Y., Jin, Z.T., Xiao, G. 2017. Effects of pulsed electric fields pretreatment and drying method on drying characteristics and nutritive quality of blueberries. Journal of Food Processing and Preservation. doi: 10.1111/jfpp.13303.
  • Yu, Y., Jin, Z.T., Fan, X., Xu, Y. 2016. Osmotic dehydration of blueberries pretreated with pulsed electric fields: Effects on drying rate, and microbiological and nutritional qualities. Drying Technology: An International Journal. doi: 10.1080/07373937.2016.1260583.
  • Gao, H., Fan, X., Chen, H., Qin, Y., Xu, F., Jin, Z.T. 2017. Physiochemical properties and food application of antimicrobial PLA film. Food Control. doi: 10.1016/j.foodcont.2016.11.017.
  • Jiang, Y., Fan, X., Li, X., Gurtler, J., Mukhopadhyay, S., Jin, Z.T. 2016. Inactivation of Salmonella Typhimurium and quality preservation of cherry tomatoes by in-package aerosolization of antimicrobials. Food Control. doi: 10.1016/j.foodcont.2016.08.031.
  • Yang, W., Sousa, A., Fan, X., Jin, Z.T., Li, X., Tomasula, P.M., Liu, L.S. 2016. Electrospun ultra-fine cellulose acetate fibrous mats containing tannic acid-Fe+++ complexes. Carbohydrate Polymers. 157:1173-1179. doi: 10.1016/j.carbpol.2016.10.078.
  • Jin, Z.T., Yu, Y., Gurtler, J. 2016. Effects of pulsed electrical field processing on microbial survival, quality change and nutritional characteristics of blueberries. LWT - Food Science and Technology. 77:517- 524. doi: 10.1016/j.lwt.2016.12.009.
  • Gao, H., Fang, X., Li, Y., Chen, H., Zhao, Q., Jin, Z.T. 2017. Effect of sanitizer washing on quality and shelf-life of fresh coriander during refrigerated storage. Journal of Food Science and Technology. 54(1):260- 266. doi: 10.1007/s13197-016-2458-7.
  • Mukhopadhyay, S., Sokorai, K.J., Ukuku, D.O., Fan, X., Juneja, V.K., Sites, J.E., Cassidy, J.M. 2016. Inactivation of Salmonella enterica and Listeria monocytogenes in cantaloupe puree by high hydrostatic pressure with/without added ascorbic acid. International Journal of Food Microbiology. 235:77-84. doi: 10.1016/j.ijfoodmicro.2016.07.007.
  • Yang, W., Sousa, A.M., Thomas-Gahring, A.E., Fan, X., Jin, Z.T., Li, X., Tomasula, P.M., Liu, L.S. 2016. Electrospun polymer nanofibers reinforced by tannic acid/Fe+++ complexes. Materials. 9(757):1-12. doi: 10.3390/ ma9090757.
  • Xiangjun, F., Hangjun, C., Haiyan, G., Hailong, Y., Yunlong, L., Peicheng, M., Jin, Z.T. 2016. Effect of modified atmosphere packaging on microbial growth, quality and enzymatic defence of sanitiser washed fresh coriander. International Journal of Food Science and Technology. 51(12):2654-2662. doi: 10.1111/ijfs.13254.
  • Jin, Z.T., Huang, M., Niemira, B.A., Cheng, L. 2016. Shelf life extension of fresh ginseng roots using sanitizer washing, edible antimicrobial coating and modified atmosphere packaging. International Journal of Food Science and Technology. doi: 10.1111/ijfs.13201.
  • Min, S., Roh, S., Boyd, G., Sites, J.E., Uknalis, J., Fan, X., Niemira, B. A. 2017. Inactivation of Escherichia coli 0157:H7 and aerobic microorganisms in Romaine lettuce packaged in a commercial polyethylene terephthalate container using atmospheric cold plasma. Journal of Food Protection. 80(1):35-43.
  • Mukhopadhyay, S., Ukuku, D.O., Juneja, V.K., Ramaswamy, R. 2016. Impact of high-pressure processing on the microbial ecology of foods. In: de Souza Sant'Ana, A. (Ed). Quantitative Microbiology in Food Processing: Modeling the Microbial Ecology, First Edition. Chichester, West Sussex, UK. Wiley- Blackwell Publisher. p.194-216.


Progress 10/01/15 to 09/30/16

Outputs
Progress Report Objectives (from AD-416): This project will focus on the integration of effective intervention technologies and treatments to enhance microbial safety of fresh fruits and vegetables with a holistic approach addressing major elements (safety, quality, and shelf-life), necessary for the implementation of technologies. The ultimate goal is to reduce the risk of foodborne illnesses associated with consumption of fresh produce, while maintaining acceptable food quality and shelf-life. Specific objectives of the research program are: Objective 1 - Develop and optimize single intervention technologies to reduce pathogen populations, maintain quality, and extend shelf-life of foods. Sub-objective 1.1. Develop and optimize aerosolizing technology and pulsed light to reduce pathogen populations, maintain sensorial and nutritional quality, and extend shelf-life of fresh produce. Sub-objective 1.2. Develop new antimicrobial packaging/coating-based technologies by incorporating natural, modified and novel materials to inactivate foodborne pathogens on fresh produce. Objective 2 - Determine the synergistic/additive effectiveness of combining non-thermal processing, antimicrobial packaging and effective chemical interventions utilizing information generated from the first objective. Approach (from AD-416): An integrated approach to enhance microbial safety while maintaining product quality and extending shelf life of fresh produce will be adopted by combining aerosolizing antimicrobials, pulsed light antimicrobial packaging and other interventions. The types of fresh and fresh-cut produce evaluated in the project will be those frequently involved in outbreaks of foodborne illnesses, those that are hard to sanitize due to surface characteristics, and those that cannot be washed. During the first part of the proposed project plan, we will develop and optimize new aerosolization systems, pulsed light technology, novel antimicrobial coating with incorporation of nature and bio-based substances, and antimicrobial packaging materials with controlled-release mechanisms triggered with either acids or pulsed light. The optimized/developed interventions and antimicrobial packaging will then be combined with each other, and with other effective antimicrobial treatments to study the synergistic or additive effects on pathogen inactivation while maintaining quality and shelf-life of fresh produce. When selecting combinations, technologies with different pathogen-inactivation mechanisms or synergistic interactions will be desirable. We will utilize the advanced oxidation, photochemical, and photothermal, and triggered- release mechanisms and other hurdle technologies to increase the efficacy of combined antimicrobial treatments. By combining effective intervention technologies and treatments, synergistic effects with a targeted 5-log reduction of common pathogens may be achieved. Pathogens to be included in the proposed project plan are Salmonella spp., E. coli O157:H7, L. monocytogenes and other emerging pathogens (such as non-O157 STECs). We will use a representative cocktail of 3-5 strains from each genera of bacteria that are associated with outbreaks of relevant fresh produce. Scientifically well-established inoculation, recovery, and enumeration procedures will be used. Appropriate controls will be included in each experiment, and experiments will be replicated independently at least three times. Inoculation of fresh produce will be achieved either by surface �spot inoculation� where specific locations on the produce surface will be inoculated or by a �dip inoculation� technique where the whole produce item will be submerged in the experimental inocula. The inoculated fresh produce will be drained and air dried in a laminar flow hood before being subjected to various treatments. After treatment with various chemicals and physical interventions, the total number of viable and injured bacteria will be determined using amended media. The effects of the individual and combined treatments on the physiochemical and sensorial quality and shelf-life will be evaluated during storage. Shelf- life will be determined based on the deterioration in product quality and increasing populations of microorganisms that render the product unacceptable to consumers. Experiments have been undertaken to evaluate the feasibility of aerosolized antimicrobials for the inactivation of Salmonella, E. coli and Listeria and quality maintenance of tomato, cantaloupe and spinach leaves, to optimize pulsed light technology for the reductions of Salmonella on tomato fruit, and to evaluate potential antimicrobials and polymers to be incorporated into packaging systems. Detailed progress to achieve the overall objectives is listed below. Spinach leaves, cantaloupe rinds, and stem scar and smooth surfaces of tomatoes were inoculated with Escherichia coli O157:H7, Salmonella Typhimurium and Listeria innocua. The inoculated samples were then treated with aerosolized hydrogen peroxide for 45 sec in a treatment chamber. Non-inoculated samples were used to study effects on quality and native microflora populations. Results showed that the effects of aerosolized hydrogen peroxide depended on types of inoculated bacteria and produce items. The treatments also significantly reduced populations of native bacteria, and yeast and mold. Furthermore, firmness, color or odor of tomato, spinach and cantaloupe was not significantly affected by the aerosolized hydrogen peroxide treatments. The aerosolized sanitizers could potentially be used for sanitizing fresh fruits and vegetables. Further studies are planned to optimize the technology. Whole and sliced apples have been found to be contaminated with Listeria monocytogenes. New formulations consisting of antioxidants and organic acids were validated for their effectiveness in preventing browning of cut apple surface and inactivation of L. monocytogenes. Solutions prepared from most promising formulations developed earlier by our group were used to dip apple slices. Color of cut surface and skin discoloration of fruit pieces were measured during simulated 21-days shelf-life. In addition, a cocktail of L. monocytogenes was added in the solutions of anti-browning/antimicrobial formulation to study inactivation of the pathogen. Results showed that the formulations maintained the freshness of cut apples while minimizing Listeria contamination. Several new antimicrobials and polymers, including olive leaf extract, doped titanium dioxide, acrylic polymer with citrus terpenes and ternenes hydrocarbons, corn fiber gum, and glycerol have been screened and evaluated for their antimicrobial activities against E. coli and Listeria and for film forming capacity. Results show that these compounds have a potential to be used as antimicrobial packaging materials and will be applied on food to improve safety and shelf life. As a physical preservation method, pulsed light has a positive consumer image and is efficient in inactivating microorganisms in a relatively short period of time compared to other technologies. Research is now on going to optimize the pulsed light system to achieve a minimum 99.9% reduction of foodborne pathogens such as Salmonella and E. coli on fresh produce. Preliminary results showed that pulse light was very promising inactivating greater than 99.9% Salmonella enterica in the stem scars of cherry tomatoes after about 30 sec treatment. No visual alteration of color and texture was observed. Research on reduction of background spoilage microflora and on retention of quality is being carrying out.

Impacts
(N/A)

Publications