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

Area of Science:

• Food Science
• Microbiology
• Acoustics

Background:

• Bacterial contamination, particularly by Salmonella, poses a significant food safety risk.
• Conventional methods for bacterial reduction may not always be sufficient or may affect food quality.
• Cavitation induced by ultrasonic waves is a known mechanism for bacterial inactivation.

Purpose of the Study:

• To evaluate the efficacy of indirect ultrasonic wave treatment in reducing Salmonella typhimurium populations in various food matrices.
• To investigate the synergistic effect of elevated temperature (50°C) on ultrasonic inactivation of Salmonella.

Main Methods:

• Salmonella typhimurium was suspended in skim milk, brain heart infusion broth, and liquid whole egg.
• Samples were treated using an ultrasonicating water bath.
• Treatments were conducted at ambient temperature and at 50°C to assess temperature effects.

Main Results:

• Ultrasonic treatment reduced Salmonella typhimurium by 2-3 log CFU in skim milk and broth in a time-dependent manner.
• A significant enhancement in bacterial reduction was observed when ultrasound was applied at 50°C.
• In liquid whole egg, ultrasonic treatment at 50°C resulted in a 1-3 log CFU reduction of Salmonella.

Conclusions:

• Indirect ultrasonic wave treatment is a viable method for reducing Salmonella contamination in certain food products.
• Combining ultrasonic waves with mild heat (50°C) significantly improves the bactericidal effect against Salmonella.
• This approach shows promise for enhancing food safety by reducing pathogenic bacteria in liquid foods.