Ascorbic Acid Oxidation a Key Factor in theInhibition or Promotion of the Tallowy Flavor in Milk

Abstract

This study is concerned with the effects of quick partial or complete photochemical and chemical (H2O2) oxidation of ascorbic acid in the milk to dehydroascorbic acid, prior to or after its pasteurization, upon the development of the tallowy flavor in milk subsequently held at 0 to 5[degree]C in absence of light. The reaction which produces the tallowy flavor could be inhibited by quick and complete photochemical or chemical oxidation of ascorbic acid in the milk to dehydroascorbic acid prior to its pasteurization and storage. Partial oxidation of ascorbic acid stimulated the development of the tallowy flavor. The tallowy flavor was not promoted by added copper (0.1 ppm.) in the milk completely depleted of its total vitamin C content prior to storage, by quick oxidation of ascorbic acid to dehydroascorbic acid and the subsequent heat treatment that takes place in pasteurization, and the magnitude of its catalysis in milk containing dehydroascorbic acid only, was found to be of much less importance that in milk containing ascorbic acid as well. The reaction which produces the tallowy flavor could be induced again by addition of ascorbic acid to milk which was first depleted of its ascorbic acid or of the total vitamin C content. Ascorbic acid oxidation in the milk during storage at low temp. is considered to be an essential link in a chain of the reactions resulting in the development of the tallowy flavor.