Composition, somatic cell count and casein fractions of ethanol unstable milks - doi: 10.4025/actascitechnol.v35i1.11481

This study determined the composition, somatic cell count (SCC) and relative percentage of a-S1, a-S2, b and k caseins in ethanol-unstable (UNA) and stable bulk milk samples. The sampling plan involved farms that supplied milk to one dairy plant located in the northeast region of São Paulo, Brazil, in May (fall), July (winter), and September (spring) 2007. Three hundred thirty-four bulk milk samples within an acceptable range of pH and acidity were included in the study and divided into two groups: a) stable milk, when protein precipitation only occurred with 78% ethanol (v/v); and b) unstable (UNA) milk, when the precipitation occurred with 72% ethanol (v/v). From the total samples analyzed, 77 (23%) were unstable in the 72% ethanol (v/v), although they have shown normal pH and acidity, and 41 (12.3%) were stable in 78% ethanol (v/v). No differences were found between relative percentages of a and b-casein in UNA or stable milks. However, UNA samples showed higher SCC, as well as lower casein and lactose contents. Results indicated that the high SCC may be involved as a causal factor for the high incidence of UNA milks in the herds studied.