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Development of Non-Heat based Combination Treatments for Pathogen Inactivation in Foods


This project aims at developing a non-heat based hurdle approach for the inactivation of pathogenic microorganisms on the surface of foods that do not undergo additional cooking before consumption, specifically fresh cut melon and ready-to-eat meat products. The proposed treatments will combine the bactericidal action of in-package Pulsed Light (PL) technology with the bactericidal and bacteriostatic effect of selected antimicrobials (organic acids and bacteriocins) to yield a unique terminal treatment that will significantly enhance the safety of the treated products. As an additional benefit, it is expected that the proposed treatment will also prolong shelf life, particularly the fresh cut melon. The following specific objectives are proposed: <ol>
<li> Test the effectiveness of individual treatments (hurdles) against selected pathogens (L. monocytogenes, E. coli, Salmonella) inoculated on high risk foods of vegetal and animal origin, with and without packaging. <li> Develop combination treatments that utilize the synergistic effects of PL and the selected antimicrobials to induce maximum microbial inactivation. <li>Evaluate the effect of the combination treatments on the quality (chemical and sensory characteristics) and shelf life of the treated foods.</ol>

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<li> Assuring a safe food supply is a permanent challenge for the Food Industry. The recent food poisoning outbreaks that affected NY and other states re-emphasized the need to develop new strategies to control food pathogens and thus protect the health of consumers and the economical viability of food companies. <li> Elimination or at least reduction of the most dangerous food pathogens, such as Listeria monocytogenes, Salmonella, or E. coli O 157:H7, in foods requires both prevention and effective intervention strategies. </OL><OL><li> This proposal focuses on the development of a novel combination (hurdle) treatment to be used as a terminal antimicrobial step for food products. <li> The proposed treatment combines the use of Pulse Light (PL), a FDA approved microbicidal surface treatment, with antimicrobial compounds that have the ability to both kill microorganisms and prevent their growth during storage. The complementary use of different treatments, at moderate doses, will work synergistically and ensure an effective control of food pathogens, with minimal effects on the foods' quality and sensory characteristics.<li> The ability of PL to kill bacteria through transparent packaging materials will bring an additional level of effectiveness to the proposed treatment. </ol>


APPROACH: Based on the proposed objectives, the following sequential strategy has been developed: <ol>
<li> Perform PL and antimicrobial treatments for:
(a) L. monocytogenes inoculated on ready-to-eat meats (b) Salmonella and E. coli inoculated on fresh cut melon. The food substrates will be surface treated with low levels of antimicrobials, then inoculated with known levels of the selected pathogens followed by PL treatment, directly and through transparent packaging. Treatment effectiveness will be evaluated by enumerating the survivors. <li> Build microbial inactivation curves and identify the range of treatment conditions with the highest antimicrobial activity for the individual treatments. <li> Identify sublethal injury effects for individual treatments (particularly PL) using live-dead staining and epifluorescence microscopy. <li> Develop and test combination treatments for each microorganism and food substrate, based on the effectiveness of the individual treatments and the presence of sublethal injury. <li> Conduct quality evaluation (sensory, texture and color) and shelf life studies for the foods subjected to the combination treatments. </ol>

Moraru, Carmen
Cornell University
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