Ascorbic Acid Oxidases

Ascorbic acid oxidase (E.C.1.10.3.3; see Ref. 77 for detailed information) plays a role in beverages such as lemon and grapefruit juices, where it is responsible for the initiation of browning and loss of vitamin C activity during storage (77). The extent of browning can be minimized by steam blanching or by the exclusion of oxygen. The rate of ascorbic acid oxidation increases markedly in the presence of metallic ions, especially copper and iron. Hence, food processed in tin cans and processing equipment should be copper free. While the loss of ascorbic acid cannot be prevented completely, it can be reduced to a minimal level during processing.

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