Enhancing microbial safety and quality of milk with ultrasonication: Kinetics modeling of pathogenic Bacteria and milk characteristics

This study investigated the non-thermal inactivation kinetics of S. aureus NCDC109, E. coli EMC17, and Salmonella Typhimurium SMC25 in milk through ultrasonication, while concurrently evaluating its impact on milk's physicochemical properties. Milk samples post- inoculation, underwent treatment with varying ultrasonic amplitudes (40 - 70%) over different time intervals (0-30 min). The highest logarithmic reduction of 6.12, 6.19, and 5.68 for S. aureus NCDC109, E. coli EMC17, and S. Typhimurium SMC25, respectively, was attained with 70% amplitude for 30 min. Weibull model exhibited superior fit with lower sum of squared errors (SSE), mean square error (MSE), root mean square error (RMSE), Akaike information criterion (AIC) values as compared to the linear model. The Weibull model accurately predicted D-values for all strains and treatments, with proper accuracy factor (Af) and bias factor (Bf)values. The 5-log reduction time for E. coli EMC17 decreased from 46.05 to 20.01 min with amplitude increasing from 40% to 70%. Ultrasonication preserved milk's physicochemical properties, encompassing particle size, zeta potential, color, pH and viscosity. This study highlights the potential of ultrasonication in the dairy sector to combat bacterial contamination in milk and provides a valuable tool for predicting and validating responses using kinetic models for pathogens in milk.