PROXIMATE COMPOSITION AND BACTERIA VIABILITY IN PROBIOTIC COTTAGE CHEESE PROCESSED BY OHMIC HEATING

Uniform heating and energy efficiency constitute the advantage of ohmic heating (OH) over conventional heat treatment of milk and dairy products, preserving nutritional compounds that can benefit consumers and microorganisms used to manufacture some dairy products. This study evaluated the effect of OH on the proximate composition and bacteria viability of probiotic cottage cheeses compared to pasteurization. The milk used to obtain the cheese was processed by OH at 20V (4V/cm; T1), 40V (8V/cm; T2), 60V (12V/cm; T3), 80V (16V/cm; T4), and 100V (20V/cm; T5) and by pasteurization (72 ºC/20 s; TP). Moisture, ash, fat, and protein analyses were carried out to determine the proximate composition, and bacterial viability was evaluated by the total quantification of lactic acid bacteria (Lactococcus lactis subsp. lactis) and probiotic microorganism (Lactococcus lactis subsp. cremoris) on 0, 7, 14 and 21 storage. Moisture content (73.8–76.8%; p>0.05) did not differ between treatments; however, ash content varied significantly (p<0.05). The highest protein content was observed in TP (19.1%), not differing (p>0.05) from T3 (19.0%), T2 (18.5%), T5 (17.7%), and T4 (17.7%). The highest fat contents were obtained in T1, T3, and T5 (9.25%, 9.25%, and 9%, respectively; p>0.05), and the lowest content in TP (7.5%; p<0.05). The initial viability (day 0) was higher in TP (6.93x10-9TP), not differing from T2 (6.63x10-9), T3 (6.39x10-9), and T4 (5.51x10-9 ). Viability was significantly reduced (p<0.05) due to the increase in the electric field on days 0, 7, and 14; however, there was no significant difference between treatments (TP–T5; p>0.05) after 21 days. In this sense, it is concluded that the low-intermediate electrical fields favored the viability of microorganisms up to 14 days of storage; however, the lowest protein and lipid degradation can be observed in the intermediate fields, with T3 (12V/cm) being the most indicated for milk processing.