Hydrostatic Pressure: Effect on Microbial Inactivation and Food Preservation

Abstract

Inactivation of Bacterial Cells Inactivation of Bacterial Endospores Inactivation of Other Microorganisms

Germination induction and inactivation of Clostridium spores at medium-range hydrostatic pressure treatment

“…The vegetative cells of bacteria, molds and yeasts and spores of fungi can be reduced by 6 log cycles at or below 690 MPa at ambient temperature or by a combination of moderate pressure and temperature. However, a 5 to 6 log destruction of spores of important foodborne Bacillus and Clostridium species needs a combination of very high pressure and high temperature (Farkas & Hoover, 2000;Ray, Kalchayanand, Dunne & Sikes, 2001;Ray, 2002). Such a drastic treatment can adversely affect the acceptance quality of many foods and thus will have limited commercial application.…”

“…Since spores of Bacillus and Clostridium are induced to germinate by low to medium range hydrostatic pressure, another approach could be to expose the spores first to pressure for optimum germination and outgrowth and then expose them to one or more physical and chemical antibacterial agents to kill the germinated and outgrowing spores before they start multiplication. The effectiveness of an oscillatory HP, heat treatment, radiation, low pH, low A w , bacteriocins of lactic acid bacteria, lysozyme, EDTA, in single or in combination were studied (Gould, 1973;Hayakawa, Kanno, Yoshiyama & Fujio, 1994;Roberts & Hoover, 1996;Stewart, Dunne, Sikes & Hoover, 2000;Farkas & Hoover, 2000;Ray, 2002). The major difference in the treatment of these antibacterial agents is that the bactericidal effectiveness of the physical methods, such as oscillatory pressure and heat or radiation treatment, is produced only at the time of application.…”

“…In contrast, a chemical bactericidal agent will be present in the food system and remain effective during initial pressurization as well as during storage. In that respect, the chemical antibacterial compounds are more effective than the physical methods (Ray, 2002). However, the success of this approach will depend upon the pressurization parameters that will result in optimum germination-induction of the bacterial spores.…”