Full text loading...
Chapter 10 : Factors Affecting Inactivation of Food-Borne Bacteria by High Pressure
Category: Applied and Industrial Microbiology
Ebook: Choose a downloadable PDF or ePub file. Chapter is a downloadable PDF file. File must be downloaded within 48 hours of purchase
High-pressure processing (HPP) is one of a number of technologies that are being considered commercially as alternatives to traditional methods such as thermal treatment, drying, or freezing of foods. This chapter provides an overview of the key factors that influence microbial behavior. The authors suggest that the development of barotolerance may have important practical implications when using pressure as a food preservation technique, especially at ambient temperatures. Vibrio spp. are one of the most pressure-sensitive groups of bacteria reported to date. It has been proposed that exponential-phase cells are inactivated under high pressure by irreversible damage to the cell membrane, while stationary-phase cells have a more robust cytoplasmic membrane that can better withstand pressure treatment. This assumption was based on the fact that exponential-phase cells showed changes in their cell envelopes that were not seen in stationary-phase cells. High pressure not only inactivates bacterial cells but also causes sublethal injury to a proportion of the population. The fate of pressure-injured cells depends on the conditions after pressure treatment, as pressure-injured cells can repair in a medium containing the necessary nutrients, given appropriate conditions. This is a problem in low-acid foods, as the recovery of injured cells during storage may result in food-borne disease or spoilage. In conclusion, it is clear that high hydrostatic pressure has the potential to kill bacteria and other microorganisms.
Inactivation of Listeria monocytogenes in PBS using a pressure treatment of 375 MPa at 20°C. N, count after pressure treatment; N0, initial count. ■, NCTC 11994; ▲, poultry isolate.
Table 1. Resistance of bacteria to high-pressure treatment