Oxidized Flavor in Milk. VIII. The Effect of the Degree of Saturation of Fat in the Ration of the Cow upon the Iodine Number of the Butter Fat and the Susceptibility of the Milk to Metal-Induced Oxidized Flavor

Feed was one of the earliest factors known to influence the susceptibility of milk to oxidized flavor. Kende (6) in 1932 reported that oleaginous (oxidized) flavor in milk seemed to occur only during the winter, and that green feed as well as fresh hay contained considerable amounts of reducing substances which tended to prevent oxidized flavor from developing. Stebnitz and Sommer (8) studied the effect of the composition of butter fat on its susceptibility toward oxidation. They found the stability of a fat toward oxidation bore an inverse relationship to the degree of unsaturation of the fat, with linoleic acid content rather than oleic acid the principal governing factor. When cows received grass as part of their ration, the butter fat became less saturated and more susceptible to oxidation. It appeared that protective substances prevented the development of oxidized flavor. Dean and Hilditch (3) found that when cows went on grass there was an abrupt increase in the oleic and linoleic acids and a parallel reduction of butyric and stearic acids in the butter fat.