Decrease of Salmonella typhimurium in Skim Milk and Egg by Heat and Ultrasonic Wave Treatment

Abstract

Ultrasonic waves induce cavitation which is lethal for many bacteria. When Salmonella typhimurium was suspended in skim milk or brain heart infusion broth and placed in an ultrasonicating water bath, the number of bacteria decreased by 2 to 3 log CFU in a time dependent manner. The killing by ultrasonic waves was enhanced if the menstruum was simultaneously maintained at 50°C. Ultrasonic reduction in S. typhimurium numbers in liquid whole egg ranged from 1–3 log CFU at 50°C. The results indicate that indirect ultrasonic wave treatment is effective in killing Salmonella in some foods.