Changes in ascorbic acid content and several enzyme activities concerning synthesis and metabolism of ascorbic acid in potatoes during storage.

Abstract

Ascorbic acid content and several enzyme activities related to biosynthesis and metabolism of ascorbic acid, namely L-gulono-γ-lactone oxidase, monodehydroascorbate reductase, dehydroascorbate reductase, peroxidase, ascorbate oxidase and polyphenol oxidase, in potato tubers were examined to clarify the relationship between physiological condition of stored potatoes and their ascorbic acid content. During the first month of storage, ascorbic acid content decreased markedly irrespective of storage temperature, after which the decrease became gradual. Since several related enzyme activities also changed markedly during the first month, they are assumed to affect the ascorbic acid content of stored tubers. Changes in storage temperature had little effect on these changes. This study showed that a marked change in ascorbic acid content of potato tubers occurred during the initial period of dormancy irrespective of storage temperature.