Effects of Seasonality on the Proximate Composition and Fatty Acid Profile in Cow Milk

Abstract

The p resent study investigated the influence of seasonality (summer and winter) on the pro ximate co mposition and on the amount of polyunsaturated fatty acids in milk fat. The amounts of lipid and protein were greater in the winter. The quantity of conjugated linoleic acid (CLA, ru menic acid, 18:2c9t11) in type B pasteurized milk (10.38 ± 0.69 in summer and 7.44 ± 0.82 in winter) was higher than in type C milk (9.90 ± 0.64 in summer and 7.25 ± 0.85 in winter) in both seasons. The amount of trans linolelaidic acid (18:2n-6t), linoleic acid (18:2n-6) and linolen ic acid (18:3n-3) had no variation between seasons and types of milk. Furthermore, the n-6/n-3 ratio of the milks analy zed after pasteurization has reduced significantly fro m (p<0.05) 7.50 ± 0.85 and 7.46 ± 1.71 in winter to 6.36 ± 0.45 and 6.72 ± 0.61 in summer for milk Type C and B, respectively.