The effect of the number of lactation cows on the indicators biochemical and antioxidant profile of pasteurized and unpasteurized milk

Abstract

Milk and milk-based products are rich in substances capable of exhibiting antioxidant activity and contain several antioxidant systems. This paper examines aspects of changes in the antioxidant status of milk, analyzed by the amperometric method, in the context of changes in the biochemical composition of milk in different lactations. Tendencies for an increase in the total concentration of water-soluble antioxidants (TAWSA) during milk pasteurization were found. In the first three lactations, an increase in TAWSA in Holstein cows correlates with an increase in average daily milk yield and somatic cell count (SCC) in milk. Thus, the TAWSA of unpasteurized milk in cows of the first lactation was 15.85±0.66 mg/L, in cows of the second lactation 17.03±2.18 mg/L, which is 6.9% more, in cows of the third lactation it was already 18.0% more than in the second – 20.77±2.91 mg/L. Within the groups, the same tendency of increasing TAWSA during milk pasteurization is also observed: 1) by +27.3%; 2) by +27.9%; 3) by +21.65%. At the same time, the dynamics of growth of TAWSA of pasteurized milk is preserved between the groups: 1) 22.11±0.33 mg/L; 2) 23.63±2.21 mg/L; 3) 26.51±2.31 mg/L. The differences in TAWSA are not only significant, but also reliable, p≤0.05. At the same time, there is an insignificant decrease in the fat and protein content in milk, while the amount of lactose does not change reliably. To draw conclusions about the statistical significance of intergroup differences, calculations were performed using the MannWhitney U test. Under the condition that Uexp. ≤ Uem. (Uem. = 27 for n=10, with α=0.05; Uem. = 19 for n=10, with α=0.01).