Progress 01/01/24 to 12/31/24
Outputs
Target Audience:During this reporting period, the project focused on developing a bench-top flume washing process informed by a fundamental understanding of the antimicrobial effectiveness of the ozone microbubble washing system. The primary emphasis is on evaluating the efficacy of this innovative technology for flume washing in fresh produce. Consequently, the project is directed toward academics, industrial scientists, and engineers interested in sustainable washing and cleaning methods to enhance food safety and defense. Findings are shared through peer-reviewed publications, presentations at scientific and professional events, and discussions at the annual grantee meeting. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Throughout the reporting period, two dedicated food science graduate students were hired as research assistants, playing a vital role in advancing the project. They underwent extensive training in the engineering design of a benchtop system that accurately represents a real flume washing system, gaining hands-on experience in its functionality and applications. Additionally, they honed their skills in a variety of food quality analysis techniques to thoroughly assess the impact of washing on produce quality. The valuable insights gained from this research were proudly showcased as a case study in the Elements of Food Engineering class at UMass Food Science, highlighting the project's real-world relevance and innovative contributions. How have the results been disseminated to communities of interest?The results have been disseminated through peer-reviewed articles in Q1 journals such as the Foods and Chemical Engineering Science. Furthermore, they have been showcased at leading international conferences, including 37th US-Korea Conference and Coference of Food Engineering. What do you plan to do during the next reporting period to accomplish the goals?This grant finishes within this tis reporting period. We will continue publishing related works from data generated from this project.
Impacts
What was accomplished under these goals?
In this reporting period, we have continuously finished and published the work from the last report period and started relevant work to aim 3 in our proposal. The major accomplishments can be summarized in two main studies. Study 1 Quality Assessment of Romaine Lettuce Washed with Different Methods This study explored the impact of ozone ultrafine bubble treatment and other washing methods on the quality of romaine lettuce during a 12-day shelf life. The lettuce was divided into leaves and stem sections to evaluate quality attributes separately. Four treatments were compared: no wash as a control, water, sodium hypochlorite solution (200 ppm free chlorine), and ozone ultrafine bubbles (pH 4, 3 ppm). Each treatment was applied for one minute, after which sodium thiosulfate solution was added to neutralize residual chlorine or ozone. The treated samples were packed in polypropylene bags and stored at 4°C, with quality monitored throughout the storage period. Vitamin C content and color were primary indicators of quality and were analyzed at various time points. Vitamin C content was determined using the 2,6-dichloroindophenol titrimetric method, while color changes were assessed using a colorimeter to measure L* (lightness), a* (redness), and b* (yellowness) coordinates. Changes in color were further quantified using ΔE values, calculated with Day 0 as the baseline. Texture analysis was performed using a texture analyzer to assess firmness, recorded as the maximum force in Newtons. In addition, sensory evaluations were conducted with over 60 participants on Days 0, 3, 7, and 10. Participants assessed the color and texture of the lettuce using a fork and provided their willingness to purchase each sample. The results showed no significant differences in vitamin C content among the treatments until Day 10, when samples washed with water, sodium hypochlorite, and ozone ultrafine bubbles exhibited greater vitamin C loss compared to the control. Color remained consistent across treatments, with no statistically significant differences in ΔE values observed throughout the storage period. Texture properties also showed no meaningful variation between treatments, indicating that the washing methods had minimal impact on lettuce firmness. Sensory evaluations revealed that participants perceived no noticeable differences in color or texture between treatments, and the ozone ultrafine bubble method did not affect consumer preference or purchasing decisions. Overall, these findings suggest that ozone ultrafine bubble treatment preserves the quality of romaine lettuce as effectively as conventional methods. Its comparable performance highlights its potential as a sustainable and effective washing solution for fresh produce. Study 2: Development of a Bench-Top Flume Washing System for Lettuce Using Ozone Ultrafine Bubbles A bench-top flume washing system was developed to simulate industrial lettuce washing conditions and evaluate the antimicrobial efficacy of ozone ultrafine bubbles. This study focused on determining the minimum effective ozone concentration required for microbial reduction and identifying key operational parameters, such as the ratio of ozone injection flow rate to flume washing flow rate, that influence antimicrobial performance. Using E. coli NRRL B-3704 K12 (ATCC 10798) as a test organism, romaine lettuce was washed under dynamic conditions to replicate industrial processes. The system enabled precise control of flow rates and ozone dosing, with real-time monitoring of ozone concentration and distribution. Results demonstrated that the injection flow rate relative to the flume flow significantly impacted ozone dispersion and efficacy. Optimized flow rates improved ozone distribution and ensured consistent antimicrobial action while minimizing ozone loss. The study established that stable ozone concentration and optimized flow dynamics achieved a consistent 2-3 log reduction of E. coli on lettuce. These findings provide critical insights for designing sustainable, effective ozone-based flume washing systems for fresh produce, enhancing food safety while maintaining quality.
Publications
- Type:
Peer Reviewed Journal Articles
Status:
Published
Year Published:
2024
Citation:
Hong, H., Rizzi, M. F., Wang, D., McLandsborough, L., & Lu, J. (2024). A Meta-Analysis on the Antimicrobial Effectiveness of Ozonated Water Treatments for Fresh Produce WashingEffect of Ozonation Methods. Foods, 13(23), 3906.
- Type:
Other Journal Articles
Status:
Under Review
Year Published:
2025
Citation:
Hong, H., Heng, J & Lu, J. Impact of Influent Properties on Microbubble Size in Pressurized Dissolution
- Type:
Other Journal Articles
Status:
Under Review
Year Published:
2025
Citation:
Hong, H., McLandsborough, L. & Lu, J. Influence of pH on the antimicrobial efficacy of ozone ultrafine bubbles in fresh produce washing.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
H. Hong, L. McLandsborough, J. Lu. August 2024. Developing the next-generation technologies for fresh produce washing. 37th US-Korea Conference (UKC) 2024, San Francisco, CA, USA
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2024
Citation:
H. Hong, C. Parra-Escudero, J. Lu. August 2024. Influence of microbubbles on impinging jet cleaning efficiency. Conference of Food Engineering (CoFE) 2024, Seattle, WA, USA.
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Progress 01/01/23 to 12/31/23
Outputs
Target Audience:The goals of this project during this reporting period remain centered on enhancing our understanding of innovative technology using ozone microbubbles, specifically in its application to food processing and safety. Our main emphasis is exploring its efficacy in flume washing for fresh produce. As a result, the primary target audience for this project comprises academics, industrial scientists, and engineers keen on sustainable washing and cleaning methods for ensuring food safety and defense. Moreover, this project caters to additional audiences within scientific communities interested in the underlying physics of bubbles. Our findings are disseminated through peer-reviewed papers and presentations at scientific and professional gatherings. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Throughout the reporting period, a food science graduate student, hired as a research assistant, dedicated consistent effort to this project. This student underwent training and actively participated in research concerning ozone microbubble technology. This involvement encompassed tasks such as characterizing gas dissolution performance and assessing antimicrobial effectiveness using diverse techniques. Moreover, an additional food science graduate student joined the project, focusing on the creation of mathematical models to optimize the system. Simultaneously, an undergraduate student majoring in mechanical engineering contributed significantly by engaging in the design and development of the bench-top flume washer system. How have the results been disseminated to communities of interest? The findings have been shared through peer-reviewed articles published in esteemed journals like the Annual Review of Food Science and Technology and Chemical Engineering Science. Additionally, they have been presented at prominent international conferences, notably at the IAFP annual meeting. What do you plan to do during the next reporting period to accomplish the goals? During the upcoming reporting period, we will continue assessing the antimicrobial effectiveness of the ultrafine bubble washing process within the benchtop flume washing system. Additionally, we will investigate their effects on the quality of lettuce, including its organoleptic and sensory attributes.
Impacts
What was accomplished under these goals?
We investigated the antimicrobial effectiveness of ozone microbubbles on romaine lettuce, exploring various processing conditions in a static setup. These conditions involved different concentrations of dissolved ozone (ranging from 1.5 to 6ppm), treatment durations (1 to 20 minutes), temperatures (12 to 27 °C), and pH levels (4, 6, 8). To represent gram-negative bacteria, we utilized E. coli NRRL B-3704 K12 (ATCC 10798) in our study. Microbubbles were generated using the pressurized dissolution method via the Nikuni Karyu Turbo Mixer (KTM20ND, Nikuni Co., Japan). Ozone gas was produced by a corona discharge generator (A2ZS-5GLab, A2Z Ozone Systems Inc.) from an oxygen tank and introduced into the bubble generator. pH adjustments were made using 1 M HCl and 1M NaOH solutions, and a pH meter (Seven Excellence, Mettler Toledo) was employed for measuring pH values. Our findings revealed that ozone microbubbles significantly increased microbial log reduction as the dissolved ozone concentration and treatment duration increased, keeping the temperature and pH constant. While minor temperature fluctuations during a 1-minute treatment showed no notable impact on microbial log reduction, a lower temperature (12°C) during a 20-minute treatment led to higher microbial log reduction compared to 17 and 27 °C. Maintaining a constant dissolved ozone concentration, ozone microbubbles at pH 4 demonstrated the highest microbial log reduction at 1 minute compared to pH 6 and pH 8. This result surpassed that of ozonated water across all treatment times. However, extending the treatment time did not elevate the microbial log reduction. At pH 6, microbial log reduction significantly surpassed that of ozonated water after 20 minutes, while no significant difference was observed at 1 and 10 minutes. At pH 8, no significant disparity in microbial log reduction was found between ozonated water and ozone microbubbles across all treatment times. We delved into the potential mechanism behind the augmented antimicrobial efficacy at pH 4. Utilizing an electrophoresis instrument (Zetasizer Nano ZS, Malvern Instruments Inc.), we measured the surface charge of both ozone microbubbles and E. coli K12. The results indicated an increase in the surface charge of ozone microbubbles with decreasing pH values, while the surface charge of E. coli K12 remained negative. Additionally, we determined the residual ozone concentration after treatment using a commercial testing kit (CHEMetrics Vacu-Vials, ozone k-7403) and evaluated the quantity of generated hydroxyl radicals using 3'-(p-hydroxyphenyl) fluorescein. Our outcomes showcased that decreasing pH values amplified the surface charge of ozone microbubbles, whereas the surface charge of E. coli K12 stayed negative. The residual ozone concentration post-ozone microbubble treatment resembled that of ozonated water treatment. Furthermore, the quantity of hydroxyl radicals was consistent across different pH values with microbubbles, but it was higher with ozonated water at pH 8 than at pH 4 and 6. We formulated a hypothesis that the heightened efficacy at pH 4 might be attributed to the alteration of the microbubble surface charge, resulting in a positive charge and facilitating increased interaction with bacteria. In addition, a bench-top flume washer has been designed and assembled capable of mimicking different flow conditions and processing times in a flume washer. This will allow us to continue the investigation of the antimicrobial efficacy of the ultrafine bubbles in a setup similar to the actual flume-washing environment.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Ubal, S., Lu, J., & Corvalan, C. M. (2023). Phoretic self-propulsion of microbubbles may contribute to surface cleaning. Chemical Engineering Science, 278, 118912.
- Type:
Journal Articles
Status:
Published
Year Published:
2023
Citation:
Lu, J., Jones, O. G., Yan, W., & Corvalan, C. M. (2023). Microbubbles in Food Technology. Annual Review of Food Science and Technology, 14, 495-515.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2023
Citation:
Hong, H., Mclandsborough, L., & Lu, J. (2023) Enhancing the antimicrobial efficacy of the ozone ultrafine bubble in romaine lettuce by altering its properties. IAFP Annual Conference 2024
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Progress 01/01/22 to 12/31/22
Outputs
Target Audience:The objectives of this project in this reporting period continuously focusing advancing the fundamental knowledge of novel ozone microbubble-based technology in relation to food processing and food safety applications, with a particular focus on flume washing of fresh produce. Therefore, the primary audience of this project is academics, industrial scientists, and engineers interested in sustainable washing and cleaning processing for food safety and defense. Additional audiences of this project also include scientific communities interested in the fundamental physics of bubbles. The audiences are notified of findings through peer-reviewed papers and presentations at scientific and professional meetings. Changes/Problems:Due to covid and visa issues, the graduate student that was supposed to be hired in the Fall of 2022 was delayed. He will be joining the research team starting in Spring 2023. We do not foresee any big consequence due to this change besides a slight redistribution of budget usage. What opportunities for training and professional development has the project provided?During the reporting period, the food science graduate student who was hired as a research assistant for this project continuously worked on this project, and the student was trained and engaged in research related to ozone microbubble technology, including characterizing gas dissolution performance and evaluating antimicrobial efficacy using various techniques. In addition, a math major undergraduate student was involved in developing quantitive modeling of the gas kinetics, as well as initiating the development of neural network modeling. How have the results been disseminated to communities of interest?The results have been disseminated through peer-reviewed articles in top-tier journals (Annual Review of Food Science and Technology, Chemical Engineering Science, Food Control) and international conferences (IFT, and IAFP annual meetings). What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we will continue finishing evaluating the antimicrobial efficacy of ozone microbubbles under various processing conditions. In addition, its impact on the quality attribution of fresh produce will also be evaluated with the support of sensory tests. These data will be used for the development of the hybrid model for optimizing the washing system. With the help of the CFD model, we will assemble a benchtop flume washer for testing under dynamic conditions. In addition, a graduate student will join in Spring 2023 to focus on modeling and optimization.
Impacts
What was accomplished under these goals?
In this reporting period, we have continuously finished the works from the last report period and started the works relevant to aim 2 in our proposal. The major accomplishment can be summarized in three main studies. Study 1: We systematically characterized bubble size distribution under a wide range of physicochemical properties of the liquid phase relevant to flume washing conditions. In addition, we also conducted a comparison study between three different major bubble size characterization techniques (laser diffraction, phase doppler particle analyzer, and shadow image analysis). Based on our study in the last report period, we will mostly be using a decompression-type microbubble generator (Nikuni) to generate bubbly flow for washing application. Here, we investigated bubble size distribution for microbubble flows generated under a range of gas flow rate (0.5, 1.0, 1.5 L/min), discharge pressure (50, 60, 70psi), temperature (5°C, 15°C, 25°C), and pH (4, 6, 8). Our results showed that smaller bubbles were found when discharge pressure is increased from 50 to 70psi, and the temperature is decreased from 25°C to 5°C. In addition, a quantitive description of bubble size distribution was established in order to summarize characteristic features describing the micro bubbly flow to be used as priori feeds for modeling and simulations. Study 2: We have started investigating the antimicrobial efficacy of ozone microbubbles in bacterial cell suspension and lettuce under various processing conditions. E. coli NRRL B-3704 K12 (ATCC 10798) was used as a representative of gram-negative bacteria in this study. Ozone microbubble was generated using a corona ozone generator (A2Z ozone) and decompression type bubble generator (KTM20ND, Nikuni, Japan) under various processing conditions such as a different inlet ozone concentration, water temperature, and pH. First, we compared the antimicrobial efficacy in bacterial cell suspension between ozonated water generated by conventional sparging and microbubbles at various dissolved ozone concentrations and treatment times (up to 5 min). Results show that microbubble ozonated water has a large potential in inactivating suspending microorganisms in water. For example, under low dissolved ozone concentration (~ 0.2 ppm), and short treatment time (< 1min) microbubble ozonated water consistently resulted in 3 log reductions (CFU/ml), which is 3 times higher than that of conventional ozonated water. This also suggests that using microbubble ozonated water will have great potential in preventing cross-contamination for flume washing applications. We also characterized gas dissolution kinetics quantitively and confirmed that microbubble ozonation has a significantly higher mass transfer coefficient and lower degradation rate. These values will also be used as feeds for modeling and simulations. Secondly, we started investigating the antimicrobial efficacy of microbubble ozonated water on Romanian lettuce inoculated with E. coli NRRL B-3704 K12 (ATCC 10798) under different temperatures (15°C, 25°C), pH (4, 6), dissolved ozone concentration (1.5 ppm, 3.2 ppm, 5.9 ppm), and treatment time (1 min to 20 min) in static condition. The purpose is to collect data enough for developing a data-driven neural network-based model for process optimizations in the next report period. In addition, we evaluated the change of color in lettuce before and after ozone microbubble treatment at 5.9 ppm dissolved ozone concentration for 20 min. L*, a*, and b* was used to interpret the direction of color change. Our results show that there is no significant color change in lettuce after ozone microbubble treatment. Study 3: A 3-D computational modeling is developed in COMSOL as a digital twin to guide the design of a benchtop flume washer to be used in the next report period. This model incorporated detailed turbulent bubbly flow dynamics, microbubble ozone gas dissolution kinetics, and microbubble characteristics. These features are connected with previous measurements and characterization and will provide a guide for optimizing the configuration of the flume washer in order to achieve an optimized washing condition.
Publications
- Type:
Journal Articles
Status:
Accepted
Year Published:
2022
Citation:
Lu, J., Jones, O.G., Yan, W., Corvalan, C.M. 2022 Microbubbles in Food Technology Annual Review of Food Science and Technology. Volume 14
- Type:
Journal Articles
Status:
Submitted
Year Published:
2023
Citation:
Hong, H., McLandsborough, L. and Lu, J., Meta-analysis of ozonated water applications of fresh produce washing. Food Control.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2023
Citation:
Hong, H., Heng, J. and Lu, J., Bubble size characterization techniques for microbubble flows. Chemical Engineering Science.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2023
Citation:
Ubal, S., Lu, J., and Corvalan, C.M., Phoretic self-propulsion of microbubbles may contribute to surface cleaning. Chemical Engineering Science
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Hong, H., McLandsborough, L., and Lu, J., Application of ozone microbubble (O3MB) for washing
of romaine lettuce. International Association for Food Protection Annual Meeting, Pittsburg, USA.
July 2022.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2022
Citation:
Hong, H., and Lu, J., " A meta-analysis on the effectiveness of ozonated water treatments in reducing foodborne pathogens on different types of fresh produce. IFT FIRST Chicago, USA. July 2022.
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Progress 01/01/21 to 12/31/21
Outputs
Target Audience:The project objectives focus upon the improvement of processes and methods as well as advacement of fundamental scientific knowledge that contribute to better understand the relationship between novel microbubble basedtechnology and food processing and food safety. Therefore, the primary audience of this project are academics, andindustrial scientists and engineers interested in sustainable washing and clearning processing for food safety and defence. Additional audience of this project also includes scientific couuminties interested in the fundamental physics of bubbles.Theaudience are notified of findings through peer-reviewed papers and presentations at scientific and professional meetings. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?During the reporting period, one food science graduate student was hired as research assistant staring Spring 2021, and the student was trained and engaged in research related to ozone microbubble technology, including setting up bench top testing rig, developing methods for characterizing microbubble size and size distribution using various optical approach including PDPA, LDA, and Shadowy image, characterizing gas dissolution performance. In addition, a chemistry majored undergraduate student was involved in microbubble washing experiments for research credit. How have the results been disseminated to communities of interest?The results have been disseminated through one peer reviewedarticle to a top tier journal (chemical engineering science) and international conference (AICHE annual meeting). What do you plan to do during the next reporting period to accomplish the goals?In the next reporting period, we will submittwo additional journal publications resulted from the works of this period that are currently under preparation. According to plan, we will start evaluating antimicrobial efficacy of ozone microbubble under various processing conditions. In addition, its impact on quality attribution of fresh produce will also be evaluated. A new graduate student will be hired starting in Fall 2022 with the focusing on developing the proposed hybrid model for optimizing ozone microbubble washing system. Lastly, we will start developing the benchtop flume washer in the next reporting period.
Impacts
What was accomplished under these goals?
In this reporting period, we have conducted 3individualstudies in relation to characterization of microbubble ozone system underobjective 1 of the project as well as the enhancing overall knowledge base of the washing process in the food industry. Study 1:We conducted a comprehensive meta-analysis on applications of ozonated water for fresh-produce wash. Our goal and objective are to identify criticalfactors when developing food processing intervention technologies using ozonated water. The meta-analysis showed that from the up-to-date studies, antimicrobial efficacy of using ozonated water on various kinds of fresh produce only has an average of1.68±1.24 log reduction, although huge heterogeneity existed between different studies. We further analyzed various moderators in meta regression model and found that besides based moderators including time, concentration, type of microorganism, and temperature, other factors such asgeometry and surface characteristics of the fresh produce, type of inoculation method, and process condition all play a significant role in antimicrobial efficacy when using ozonated water. Amongst the different processing methods, sparging shows stronger biocidal effect, suggesting the washing power of bubbles. Study 2:We have set up the testing rig forinvestigatingozone microbubblegas dissolution abilityand stability at variousprocessing conditions. Our testing includes two different microbubble generators: a decompression type generator (Nikuni) and a swirl flow type generator (ECO-bubble). The two generators are capable of generating microbubbles at different concentrations with an order of magnitude difference. Decompression type generates bubble at approximately 1% v/vwhile swirl flow type generates bubble at approximately 0.1% v/v, while both microbubble solutionhas similar size distributions. Our testing rig uses a corona ozone generator (A2Z ozone), capable of generating ozone at a flow rate of 0.1-1 L/min with ozone inlet concentration from 0-80 ppm. We have compared gas dissolution ability between microbubbles and millimeter bubbles. Using ozone at initial concentration of 10 ppm at flow rate of 0.15L/min through swirl flow microbubble generator, the gas dissolution rate of dissolved ozone, measured by a Q45H/64 dissolved ozone meter, is as fast as the case when using the same ozone concentration at the flow rate of1.5 L/min through millimeter bubbler. In addition, our results show that microbubble ozonation also show a longer half-life time, indicating enhanced stability. In addition, we also characterizedhow bubble size and concentration are affected by temperature (5, 15, 20 C) and pH (4, 6, 8). Our results showed that both pH and temperature have no effect on bubble size while higher pH yields larger microbubbleconcentration, which is caused by increased zeta-potential on microbubble interfaces at high pH. These results would be critical in controlling, understanding and quantifying ozone microbubble's performance in objective 2 and 3. Study 3:This is a studyin collaboration with members in a research interest group PI forms with external collaborators (Dr. Carlos Corvalan fromPurdue University and Dr. Sebastian Ubal from CONICET). This research interest group focuses on advancing fundamental mechanistic understanding of the fluid physics of food and biological processing. This study usedhigh fidelity computational fluid dynamics to characterize the rate at which microbubble interacts with each other through coalescence when approaching contaminated area, such as fresh produce surface. Our finding revealedfor the first time that microbubblethat coalescence with other microbubbles nearcontaminated areaexhibitsa self-propelling process following the coalescence. These findings suggestednew washing and cleaning mechanisms of microbubble flows and could be usedfor improved cleaning performance.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2021
Citation:
Hong, H. and Lu, J. 2021.Parametric Study on Physicochemical Properties of Ozone Microbubble - Applications to Fresh Produce Washing AICHE Annual Meeting. Boston, MA USA. Nov, 2021.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2021
Citation:
Ubal, S., Lu, J., Grifonic, R., Bozzolid, F., and Corvalan, C.M. Coalescence preference of surfactant laden bubbles of equal size. Chemical Engineering Science
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