RESUMO
The aim of this research was to determine the physicochemical properties, microbial counts and aflatoxin M1 (AFM1) levels of thermoultrasonicated, pasteurized and untreated milk (control) at days 1, 7 and 14 of storage. Thermoultrasound treatment was performed at a rate of 20â¯kHz for 10 or 15â¯min and 95% amplitude on homogenized and non-homogenized milk samples. Results showed that most physicochemical parameters were within the Mexican norms established for milk. Ultrasound treatment for 15â¯min reduced solids precipitation (pâ¯<â¯0.05) in unhomogenized milk during storage as compared to the pasteurized milk. All samples complied with aerobic mesophilic counts limits set by the Mexican norm except the control and the homogenized milk sample which was thermoultrasonicated for 10â¯min. Enterobacteriaceae counts of pasteurized and 15â¯min-thermoultrasound homogenized milks complied with the norm. The lowest levels of AFM1 were found in the 10â¯min-thermoultrasound unhomogenized milk (0.15⯱â¯0.05â¯pgâ¯AFMâ 1E/mL) one day after storage. Thermoultrasound did not affect the color of samples but homogenized milk treated for 10â¯min exhibited less total color difference. A high phenolic content was found in thermoultrasound and pasteurized milks on day 1. Thermoultrasound could be an alternative to milk pasteurization that preserves the physicochemical and microbiological quality of milk while reducing AFM1 levels.