Changes of ascorbic acid content in fruits and vegetables during the process of cooking were studied. Ascorbic acid content was determined by 2, 4-dinitrophenylhydrazine method, and L-ascorbic acid, dehydroascorbic acid and 2,3-diketogulonic acid were separated by Dowex 1-X2 column chromatography. It was observed that, in nonheating fruits and vegetables, L-ascorbic acid was oxidized rapidly by ascorbic acid oxidase and the formed dehydroascorbic acid was not changed further. This means that

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... ydroascorbic acid was stable. On the other hand, when the vegetables were heated. slowly for a long time, ascorbic acid was oxidized slowly by ascorbic acid oxidase, and then decomposed by heat. No oxidation and decomposition occurred in case of the rapid heating. Changes of ascorbic acid content depended upon heating conditions. Generally, the loss of ascorbic acid in the cooking process by heating was under about 50%. In conclusion, no significant change occurred in ascorbic acid content during the process of cooking except a few cooking method, as we considered that dehydroascorbic acid showed the same physiological efficiency as L-ascorbic acid.