Mechanism of inactivation of heat‐tolerant spores of <i>Bacillus stearothermophilus</i> IFO 12550 by Rapid Decompression

Abstract

ABSTRACT The effect of three rapid decompression methods to clear the mechanism of inactivation of heat tolerant spores of Bacillus stearothermophilus IFO 12550 was investigated. Pressurization of the spores at 200 MPa and 75°C for 60 min caused a kill of 10 4 CFU/mL by the link‐motion system but the nonrotational rod valve and E.G. seal methods gave a kill of about 10 3 CFU/mL. Sterilization was due to the physical breakdown of spore coat, and was induced by its physical permeability of water at high pressure and temperature. Rapid decompression by the link‐motion system at 200 MPa decreased the D‐value of the spores from 3000 min (100°C, one atmosphere) to 6 min, 11 min, and 17 min at 95, 85, and 75°C, respectively.