Abstract: In order to extend the shelf life of foods and kill spores under mesothermal conditions, ultrasound combined with heat treatment and germination inducers was used to explore the optimal conditions for killing Bacillus subtilis spores. The results showed that the germination rate of spores was up to 98.23% under the following conditions: ultrasonic power 600 W, ultrasonic frequency 25 kHz, 60 ℃,L-alanine 50 mmol/L and inosine 6 mmol/L. When other conditions were maintained same, the germination rate of spores was improved significantly by decreasing ultrasonic power (900, 600, 300 and 100 W), and inactivation of the spores could guarantee food safety and quality.

Key words: ultrasound, inducer, Bacillus subtilis, spore, germination