Control of the Generation Time of Microorganisms by Long-term Application of Hydrostatic Pressure of 50 MPa or Less

Abstract

Hydrostatic pressure treatment of food has attracted attention because it can inactivate microorganisms without heating. To understand the changes in microbial proliferation, we selected Escherichia coli, Bacillus cereus and Saccharomyces cerevisiae. The generation time of each microorganism was determined based on the number of viable cells before and after application of pressure of 20 to 50 MPa for 6 to 24 hours at 10 to 45°C. The pressure values at which the proliferation of microorganisms stopped were obtained under the respective temperatures. Hydrostatic pressure (50 MPa or less) was applied to unpasteurized sake and fruit and vegetable juices with the goal of reducing the number of viable cells and bacteria, thereby extending the use-by date. A relatively low pressure was found to lengthen the time food could be stored at low cost using pressure-storage. Our findings are considered applicable to food industry practices.