Relation of Natural Copper in Milk to Incidence of Spontaneous Oxidized Flavor1,2

Abstract

Summary Milk as it is produced by the cow contains a low but variable concentration of copper (natural copper). Results are presented that show a relatively high concentration ( ca. 0.2 p.p.m.) of natural copper in early lactation milk, and a level of about 0.02–0.04 p.p.m. for most cows during the remainder of a lactation period. These results are similar to others reported recently. No difference was observed between pasture and dry feed in the natural copper concentration in the resulting milk. When cows on dry feed were drenched with large (10-g.) doses of copper sulfate, there was an increase in the natural copper content of their milk and in the incidence and intensity of spontaneous oxidized flavor. For cows on an alfalfa hay-grain concentrate ration, and not in early lactation, a highly significant correlation was observed between the concentration of natural copper in milk and the incidence and intensity of spontaneous oxidized flavor.It is concluded that the copper present in milk as it comes from the cow is an important catalyst of oxidized flavor.