Seasonal variations in fatty acids composition of cow's milk

Milk and dairy products have a considerable share in the diet of the people, thus milk fat repre-sents one of their important components. Biological value of milk fat is connected with availability of irreplaceable fatty acids, phospholipids and vita-mins. Therefore close attention is paid to the com-position of milk fat and the ways of its change by production and consumption of dairy products. It is known that seasonal and climatic changes of keep-ing and feeding cows have essential impact on fat composition. The researches in this direction in other countries for the assessment of consumer qualities of ready production during the current pe-riod, and also for forecasting of its structure in the next years are constantly conducted. Therefore studying characteristic seasonal features of com-position of fatty acids of the whole pasteurized drinking cow's milk was the purpose of the study. In the study the samples of the whole pasteurized drinking cow's milk with mass fraction of fat from 2.8 to 4.5 % were used. The extraction of fatty phase was carried out with n-Hexane. Methyl air was prepared using 2 M of solution of methylate of sodium in methanol. The received mix of methyl ester of fatty acids was divided in gas chromato-graph with using of selective column 100 m long and with an internal diameter of 0.25 mm. 16 fatty acids making in the sum more than 90 % from all fatty acids were allocated and characterized. The greatest differences were recorded in the concen-tration of α-linolenic acid. Its level during summer period increased almost twice in comparison with winter. It was revealed that maximum values in win-ter reached short- and medium-chain acids, but in summer - long-chain fatty acids. The level of satu-rated fatty acids increased slightly in autumn and winter, but monounsaturated and polyunsaturated - in summer. These results are in good agreement with foreign resources data.