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

The present study investigated the influence of seasonality (summer and winter) on the proximate composition 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, rumenic 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 linolenic acid (18:3n-3) had no variation between seasons and types of milk. Furthermore, the n-6/n-3 ratio of the milks analyzed after pasteurization has reduced significantly from (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.