Growth Inhibition of Microorganisms by Hydrostatic Pressure

Abstract

The pressure range that prevents growth of microorganisms (two yeast, three lactic acid bacteria, E. coli, three bacilli and one clostridium) was investigated in order to apply it to food processing. The growth of the microorganisms could be restrained in a pressure range of 40-70 MPa depending on the species of microorganism. Growth of Lactobacillus plantarum was inhibited at 70 MPa, and two kinds of yeast at 40 MPa. The pressurization treatment is presumed to induce the germination of the spores of Bacillus and Clostridium, and the germination of B. subtilis and B. stearothermophilus were especially remarkable. Most of the germinated spores were killed at the optimum growth temperature of each microorganism under pressurized conditions. Practical usefulness of these results was verified in the autolysis process of fish meat without decomposition. Growth inhibition and inactivation of spores by pressurization treatment at less than 100 MPa can be utilized as a new technique for killing microorganisms and for producing food.