Oscillatory Compared with Continuous High Pressure Sterilization on Bacillus stearothermophilus Spores

TO ESTABLISH a sterilization method with minimal heating, the effect of high pressure on bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus . After exposure to 800 MPa for 60 min at 60°C, the spore count decreased from 10 6 to 10 2 /mL. However, exposure to the same pressure at room temperature did not cause significant change in spore numbers. The synergistic effect of high pressurization on the bacteriostatic action of sucrose fatty acid ester at low concentration (< 10 ppm) was pronounced with sucrose palmitic acid ester but not with sucrose stearic acid ester. Oscillatory pressurization was more effective for spore sterilization. Six cycles oscillation of 5‐min pressurization with 400 MPa at 70°C decreased the spore count from 10 6 to 10 2 /mL, and with 600 MPa, complete sterilization was achieved.