Changes in the Vitamin C Content and Enzyme Activities Involved in the Synthesis and Oxidation of Ascorbic Acid in Cut Vegetables

摘要

The total vitamin C (VC) contents in commercially obtained cut onion and cut carrot were almost the same as these contents in the fresh vegetables, but the dehydroascorbic acid (DHA) contents in the cut vegetables were higher than those in the fresh vegetables. The DHA content and the activities of ascorbate oxidase (EC 1.10.3.3) and ascorbate peroxidase (EC 1.11.1.11) in the cut vegetables were higher for crosswise cutting than for lengthwise cutting. The total VC content differed among tissues of the same vegetable f i.e., the VC content at the mid-layer of the onion bulb, and in the cortex and inner pith of the carrot root were higher than that in the other parts. The pattern of increase in the total VC content of cut vegetables incubated at 25℃ was similar to that of the increase in L-galactono-γ-lactone dehydrogenase (EC 1.3.2.3) activity. When cut onion was transferred from 25℃ to 4℃, increases in the total VC and L-galactono-γ-lactone dehydrogenase activity stopped, but the DHA content and ascorbate peroxidase activity increased markedly.