Abstract
Contents of total vitamin C (ascorbic acid and dehydroascorbic acid) differed among tissues of the same vegetables, that is, the content of outer leaves of cabbage was higher than that of the inner leaves, the content of younger leaves of lettuce was higher than that of the mature leaves, the content of cotyledon of radish seedlings was higher than that of the epicotyl, the content of cortex of carrot was higher than that of the pith.
When cabbage leaves were washed and soaked in water after cutting, vitamin C content was decreased, the loss of vitamin C was higher in the case of those cut into smaller pieces. Vitamin C content of cabbage decreased during storage at room temperature after cutting, but in the roots of carrot, Japanese radish and sweet potato and potato tubers vitamin C contents increased after slicing. The increase in vitamin C contents of potato tubers and sweet potato roots were prominent where ascorbate oxidase activity was not detected.
Vitamin C contents of cut-cabbage and -carrot commercially available were lower than those of the fresh vegetables. But the contents of cut-cucumber, -radish seedlings and -lettuce were the same as those of fresh vegetables.
Ascorbate oxidase activities of several vegetables were assayed after improving the method for preparation of enzyme extract. Ascorbate oxidase activities of vegetables such as carrot, cabbage and Japanese radish were increased after cutting or slicing. However, neither ascorbate oxidase activity of potato tubers and sweet potato roots was detected in the fresh tissues nor in the sliced discs.
