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Inactivation and injury of Salmonella enterica serovar Enteritidis in buffer and whole liquid egg during treatment with mild heat, ozone and their combinations

Morrison, Nathan J
http://rave.ohiolink.edu/etdc/view?acc_num=osu1434646616

Abstract Details

2015, Master of Science, Ohio State University, Food Science and Technology.
The food industry is in need of better processing combinations to reduce the risk of pathogens in food. Combining mild antimicrobial treatments will produce a higher quality food product from both a sensory and microbial safety standpoint. Ozone and mild heat have shown promise as synergistic treatments when used in combination in some food products. The current model is a guess-and-check system, and a predictive model for which treatment combinations work is not available. During an antimicrobial treatment, bacterial cells that are sublethally injured may rejuvenate afterwards. By assessing cell injury produced by different ozone and mild heat treatments, it may be possible to maximize the effect of combination processes. The application of this research can be used in liquid egg products, where proteins may be damaged by heat pasteurization that is currently mandated by the USDA. The objectives of this research were: (i) to determine the rate and magnitude of sublethal injury exhibited by Salmonella Enteritidis after treatment with mild heat and ozone; and (ii) to develop a method of treating liquid whole egg products with a combination of mild heat and ozone for potential pasteurization treatment. Salmonella Enteritidis was treated with mild heat and aqueous ozone in a single-pass filtration system. Total and healthy cell populations were enumerated by plating on nonselective and selective media, respectively, after each treatment. In low inoculum (107 CFU/filter) experiments, heat treatment of Salmonella Enteritidis resulted in a D55°C-value of 2.5 minutes for the whole population and a D55°C-value of 1.5 minutes for healthy cells only, causing a significant amount of sublethal injury. Ozone treatment (1 ppm) resulted in a 1.9 log reduction after 5 seconds but sublethal injury was not detected until 60 seconds of treatment. Combining the treatments sequentially improved the microbial kill, but did not result in synergistic inactivation against Salmonella Enteritidis. Application of heat-ozone combination to high-inoculum (108 CFU/filter) cell suspensions had antagonistic effects compared to ozone treatment alone. Cell clumping upon heat treatment prevented the two treatments from being synergistic in the filtration treatment method that was used. Liquid whole eggs were treated with mild heat and aqueous ozone. Heat treating eggs at 55.5 oC for 15 minutes reduced Salmonella Enteritidis by 1.9 log CFU/mL while ozone (8 ppm) did not cause a reduction in the Salmonella Enteritidis population. A combination process in which liquid whole eggs were treated with aqueous ozone after heat treatment resulted in a synergistic inactivation, reducing the Salmonella Enteritidis population by 3.8 log CFU/mL. Based on this outcome, a combined process of mild heat and ozone treatment can be made sufficiently lethal to meet pasteurization requirements in liquid whole eggs. Further optimization of the process in the future will ensure a higher quality liquid egg product and minimize the addition of water to the product during ozone treatment.
Ahmed Yousef (Advisor)
V.M. Balasubramaniam (Committee Member)
Monica Giusti (Committee Member)
87 p.
Food Science; Microbiology

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Citations

  • Morrison, N. J. (2015). Inactivation and injury of Salmonella enterica serovar Enteritidis in buffer and whole liquid egg during treatment with mild heat, ozone and their combinations [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1434646616

    APA Style (7th edition)

  • Morrison, Nathan. Inactivation and injury of Salmonella enterica serovar Enteritidis in buffer and whole liquid egg during treatment with mild heat, ozone and their combinations. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1434646616.

    MLA Style (8th edition)

  • Morrison, Nathan. "Inactivation and injury of Salmonella enterica serovar Enteritidis in buffer and whole liquid egg during treatment with mild heat, ozone and their combinations." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1434646616

    Chicago Manual of Style (17th edition)

osu1434646616
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This open access ETD is published by The Ohio State University and OhioLINK.