HEAT STABILITY OF CASEIN AND ETHANOL STABILITY AT 68, 72, 75 E 78%, IN BOVINE MILK

Abstract

Milk heat stability, evaluated through alcohol or alizarol test, is affected by several factors, the main one is milk acidificat ion. However, enzymatic hydrolysis, high somatic cells counts (SCC), excess of calcium ions and ethanol addit ion also af fect its stability to alcohol , reducing its correl ation with heat stability. The objective of this work was to determine the occurrence of instable non acid milk (LINA) in Sapopema-PR, evaluate heat stability of LINA and its relation with SCC and total bacteria count (TBC) and also evaluate the interference of alcohol concentration, used to perform alcohol test, on milk stability. A total of 85 samples were submit to alcohol test at 68, 72, 75 e 78%, determination of Dornic acidity, boiling test , SCC and TBC. High occurrence of LINA was observed. The highest frequency of LINA 65,88% occurred at alcohol concentration of 78% v/v and the lowest 15,29% at 68% v/v. With one exception, LINA samples were stable to boiling test, showing that its rejection by industry that produces pasteurized milk and dairy products would be unnecessary. The means obtained to SCC and TBC were elevated in both LINA samples and instable samples with acquired acidity.