MINAS FRESCAL CHEESE ELABORATED WITH THERMOSONICATED RAW MILK: BIOACTIVE COMPOUNDS, MICROBIAL REDUCTION, AND CONSUMER ACCEPTANCE.

Minas Frescal cheese is a typical Brazilian fresh cheese, which presents a 14-25-day shelf life due to its high moisture, which is usually manufactured using pasteurized milk. Thermosonication (TS) is an alternative process that involves low heat in addition to ultrasound waves, with positive applications in dairy foods. However, more investigations are needed to confirm its adequation for cheese processing. Therefore, this study aimed to evaluate the influence of raw milk processing by TS (160, 400, and 640 W, 72-75 °C/10-15 s) on the manufacture of Minas Frescal cheese. The products were evaluated for microbial reduction (aerobic mesophilic and psychotropic bacteria, lactic bacteria, AMB, APB, LAB), bioactive compounds (DPPH, ACE, total phenolic count, α-amylase, and α-glucosidase), and sensory acceptance (60 consumers, unstructured nine hedonic points). Cheeses manufactured using pasteurized (HTST) and raw milk (control) were also performed for comparative purposes. HTST generated less microbial inactivation for all microbial groups than TS treatments (p < 0.05). AMB was reduced by 1.63 log CFU/g in the HTST treatment, while the TS treatments resulted in reductions between 2.22 and 2.35 log CFU/g. The HTST treatment reduced APB count by 3.00 log CFU/g, while the TS treatments reduced between 3.30 and 3.85 log CFU/g. HTST treatment reduced LAB count by 2.04 log CFU/g, and the TS treatments reduced between 3.60 and 3.65 log CFU/g. The cavitation effect, associated with the generation of microbubbles, generates a more significant microbial inactivation when compared to conventional heat treatments. The turbulence generated by the collapse of the microbubbles can break the cell membrane of microorganisms, resulting in the leakage of cellular components. Regarding bioactive compounds, HTST samples exhibited lower values concerning the samples treated by TS (p < 0.05). The higher levels of bioactive compounds in the treated samples, in general, can be explained by the release of some bioactive peptides by TS processing. Among the TS samples, only the ACE values showed a statistically significant difference between them, where TS160 presented a significantly lower value (23.5%, compared to 46.5 and 43% of TS400 and TS640, respectively, p < 0.05). The DPPH values were higher in the samples treated by TS by about 2.5 times concerning the HTST treatment, while α-glucosidase and α-amylase presented values more than double. TS Minas frescal cheese sample presented improved sensory acceptance when compared to HTST samples (7.89-8.05 against 6.34 for overall liking, 7.02-7.94 against 6.89 for flavor, 7.05-6.84 against 6.04 for texture, and 7.98-7.65 against 6.99 for aroma, p<0.05), suggesting an improvement of TS for all sensory attributes. TS is an interesting process to be considered for raw milk for Minas Frescal cheese processing and should be considered by the Brazilian dairy industry.