Vitamin C, Hydrogen Peroxide, Copper and the Tallowy Flavor in Milk

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Abstract
It has been demonstrated that ascorbic acid oxidation is an essential link in the chain of the reactions resulting in the development of the tallowy flavor in milk, and that apparently the oxidation of the lipid fraction of the milk is coupled to that of ascorbic acid when a certain equilibrium between ascorbic and dehydroascorbic acids has been established. The evidence is presented to show that a promotor (an enzyme) of ascorbic acid oxidation by H2O2 might be responsible for its quick conversion to dehydroascorbic acid and that it is not the free H2O2 formed in the course of ascorbic acid oxidation which causes the breakdown of the lipid fraction of the milk, resulting in the development of the tallowy flavor. This view is supported indirectly by the observations indicating that H2O2 formed in the reaction would be used to oxidize the residual ascorbic acid as in the milk to which it was added; and that in the absence of a suitable catalyst the addition of H2O2 to milk completely depleted of its total vitamin C content does not result in the development of the tallowy flavor.The reaction which produces the tallowy flavor is catalyzed by added copper in the presence of H2O2, providing the agent was added to milk completely depleted of its total vitamin C content, or the amt. of the agent added was in excess of that required to oxidize its ascorbic acid content. Under the exptl. conditions the catalysis of the tallowy flavor by Cu were confined in a critical region, the limits of which were apparently detd. by H2O2 conc.