Effects of microwave and ultrasonic wave treatment on inactivation of Alicyclobacillus

The objective of this study was to determine the effects of microwave (MW), ultrasonic wave (UW) and their combination treatments for the same length of time (10 or 30 min) on the inactivation of vegetative cells of three different strains of Alicyclobacillus, (Alicyclobacillus acidiphilus DSM 14558^T, Alicyclobacillus acidoterrestris DSM 3922^T and Alicyclobacillus cycloheptanicus DSM 4006^T) in a laboratory medium. The results showed that A. acidoterrestris DSM 3922^T seemed to be the most susceptible strain. It was also found that when MW or UW was employed separately, UW was more effective and the effectiveness of MW and UW was improved as the power and exposure time increased. By comparison, UW treatment followed by MW was significantly better than the treatment of MW followed by UW. Furthermore, combined MW and UW treatment had a markedly better effect than separate MW processing, but had a less effect than UW alone, except that the inactivation of A. cycloheptanicus DSM 4006^T was significantly increased (P < 0.05) by the 30‐min treatment of UW (400 W for 20 min) + MW (900 W for 10 min).