23-3 |
Fundamentals of microbial inactivation by PEF |
J. RASO-PUEYO, Tecnología de los Alimentos, Universidad de Zaragoza, Dpto. Producción Animal y Ciencia de los Alimentos, C/ Miguel Servet, 177, Zaragoza, 50013, Spain Studies conducted in the last years on microbial inactivation by pulsed electric field technology (PEF) have shown its potential as a nonthermal pasteurization method for liquid foods. Critical factors involved in microbial killing by PEF are well known. However, kinetics of microbial inactivation by PEF is still unclear and the underlying mechanisms of microbial inactivation have not been fully elucidated. Quantification of the influence of critical factors requires the development of mathematical models that describe the inactivation kinetics of food spoilage and pathogenic microorganisms. These models are essential components of hazards analysis and critical control point systems, and very useful tools to equipment manufactures and food processors to predict and control the safety and shelf life of foods at the design state. This paper will present the modelling of kinetics of inactivation of different foodborne microorganisms (Listeria monocytogenes, Yersinia enterocolitica , Salmonella spp, Escherichia coli, Enterococcus faecium and Sacharomyces cerevisiae ) under different experimental conditions. These models permit comparing the resistance of different microorganisms to PEF and to set up combinations of treatment time and electric field strengths for achieving at least a 5-log reduction. Recently, we have demonstrated in our laboratory that under some experimental conditions microorganisms can be sublethally injured by PEF treatments. The occurrence of sublethal injury in several microorganisms will be presented and its practical implications in terms of food safety and in the design of preservation systems by combined processes will be discussed.
Session 23, Pulsed electric fields: An update
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