Changes in Sugar, Organic Acid, Amino Acid, Ascorbic Acid and Carotenoid Contents of Citrus 'Shiranuhi' Fruit during Cold Storage

Abstract

　In this study, we investigated the changes in the sugar, organic acid, amino acid, ascorbic acid and carotenoid contents of citrus 'Shiranuhi' fruit stored at 5℃ and packaged in polyethylene film for 5 months. Fruit weight slightly decreased during the storage. A significant reduction in organic acid content was observed with no significant change in sugar content. Consequently, sugar-acid ratio increased significantly during the storage. Sucrose content showed no change during the storage, whereas glucose and fructose contents decreased. The organic acids detected were citric acid and malic acid. Both citric acid and malic acid contents decreased during the storage. Asparagine, arginine and aspartic acid were the major amino acids detected. No significant change in total amino acid content was observed throughout the storage; however, the changes in the amounts of all amino acids tested differed. A small change in L-ascorbic acid content was observed during storage with a decrease in dehydroascorbic acid content. β-Carotene and β-cryptoxanthin were the main carotenoids detected. No significant change in β-cryptoxanthin content was observed. β-Carotene content increased markedly and, after five months of storage, reached a value approximately threefold higher than that at the initial storage time.