OHMIC HEATING PROCESSING ON SHEEP MILK

One of critical points in controlling the quality and safety of dairy products is the choice of the best conservation method to use. The objective of this work was to evaluate the stability of physical-chemical and microbiological parameters in sheep's milk treated by ohmic heating (OH) at different voltages. Compared with HTST, OH was able to reduce 40% of the total processing time. The mean values of pH, titratable acidity and relative density of OH samples were in agreement with available data in literature. Regarding color, OH samples subjected to voltages of 11.23 V/cm and 20.86 V/cm showed similar significant values to raw sample for L*; for b*, the sample submitted to 20.86 V/cm presented a significant similar result to raw sample, whereas HTST sample was the one differing from others. Microbiological results demonstrated that, after thermic processing, all sheep milk samples were within the current Brazil legislation standards, and seven days after the processing, only raw sample presented outside the limits. Changes occurred in OH acidity, density and colorimetry values compared to raw sample possibly related to variation on fat content after heat treatment. It was ob-served that OH was less aggressive in maintaining the quality of the final product. Sheep milk presented high amount of total fatty acids, mainly ω9, as reported by literature. The OH influenced significantly on fatty acids individually between samples, however, its total were similar. The differences of milk composition observed in literature and in this study reflect the need for specific national legislation to control the quality of sheep matrix.