The Oxidation of Vitamin A and Carotene in Milk Fat

While the literature indicates that the problem concerning oxidation of milk fat received considerable attention in past years, the mechanism involved and particularly the role which vitamin A and carotene play in this phenomenon are not yet well understood. Our studies on the effects of ordinary temperatures, however (5-60 C.), and the time of holding upon the keeping quality (as judged organoleptically) of the fat from the milk in which lipolysis was checked by pasteurization immediately after withdrawal from the mammary gland have shown that the development of oily-tallowy and finally dominantly tallowy flavors in the samples was accompanied by corresponding losses in their vitamin A and carotene contents. Furthermore, it was observed that, although the bitter flavor and unpleasant odor of the milk in which lipolysis was produced by temperature changes (7) were not inherited by the fat, nevertheless, the keeping quality of the latter was considerably lowered. Our data (9) concerning the distribution of lipase-Hberated fatty acids between the fat and the plasma of the milk have indicated that the o]eic acid was largely retained by the fat, while all of the butyric and most of the caproic and caprylic acids were retained by the plasma.