Oxidative stability and quality of raw Saanen and Alpine goats milk

Abstract. The milk composition and concentration of thiobarbituric acid reactive substances (TBARS) and superoxide dismutase (SOD) activity in fresh and refrigerated raw goat milk of Saanen and Alpine breed at the breeding period were investigated. Low average milk fat, SNF and lactose content were determined in both breeds with no significant differences between breeds regarding the milk yield and milk composition. The significantly higher somatic cell count (SCC) was detected in Saanen goats. The SOD activity and TBARS concentration were significantly higher 14 h after the collection and cold storage in both breeds of dairy goats with no difference between the breeds. In the Alpine goats the TBARS concentration was negatively correlated with urea concentration, and in the milk of the Saanen goats the TBARS was positively correlated with proteins and SCC. The higher SCC in the Saanen goats may have caused higher production of secondary oxidative products catalysed by the enzyme superoxide dismutase from polymorphonuclear granulocytes present in the udder, or by some other enzymes that participate in oxidation of the milk constituents. The energy shortage and protein surplus in the diet of the dairy goats may have induced the higher degree of lipid mobilisation and a consequent increase of polyunsaturated fatty acids (PUFA) that are easily prone to oxidation and formation of the secondary oxidative products.