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High-pressure inactivation of Saccharomyces cerevisiae and Lactobacillus plantarum at subzero temperatures.

Perrier-Cornet JM, Tapin S, Gaeta S, Gervais P

Laboratoire de Génie des Procédés Alimentaires et Biotechnologiques, ENSBANA, 1 esplanade Erasme, 21000 Dijon, France. jperrier@u-bourgogne.fr

High hydrostatic pressure is a new technology in the food processing industry, and is used for cold pasteurization of food products. However, the pressure inactivation of food-borne microorganisms requires very high pressures (generally more than 400 MPa) and long pressure holding times (5 min or more). Carrying out pressure processing at low temperatures without freezing can reduce these parameters, which presently limit the application of this technology, in keeping the quality of fresh raw product. The yeast, Saccharomyces cerevisiae and the bacterium, Lactobacillus plantarum were pressurized for 10 min at temperatures between -20 and 25 degrees C and pressure between 100 and 350 MPa. Pressurization at subzero temperatures without freezing significantly enhanced the effect of pressure. For example, at a pressure of 150 MPa, the decrease in temperature from ambient to -20 degrees C allowed an increase in the pressure-induced inactivation from less than 1 log up to 7-8 log for each microorganism studied. However, for comparable inactivation levels, the kinetics of microorganism inactivation did not differ, which suggests identical inactivation mechanisms. Implications of water thermodynamical properties like compression, protein denaturation, as well as membrane phase transitions, are discussed.

Published 10 January 2005 in J Biotechnol, 115(4): 405-12.
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