Effect of maturation stage and storage temperature and duration on β-cryptoxanthin content in satsuma mandarin (Citrus unshiu Marc.) fruit

In satsuma mandarin fruit (Citrus unshiu Marc.), β-cryptoxanthin is a major carotenoid and an important quality component in the juice sacs. The stage of maturity and storage conditions of satsuma mandarin fruit shipped to markets varies. However, the effects of maturation stage, storage temperature and duration on changes in β-cryptoxanthin content have not been fully studied. In the present study, fruits were harvested at different maturation stages, and changes in β-cryptoxanthin content in the juice sacs were investigated during storage at temperatures from 5 to 20℃. At 20℃, in fruit harvested while β-cryptoxanthin is still being accumulated on the tree, the content continued to increase following 15 days of storage. However, in the fruit without β-cryptoxanthin accumulation on the tree, the content did not increase. At 10℃, in the fruit accumulating β-cryptoxanthin on the tree, the content continued to increase after 14 days’ storage, whereas in the fruit without β-cryptoxanthin accumulation, the content did not increase after 14 days’ storage but increased after 30 days’ storage. At 8℃, the increase in content was also observed in the fruit when stored for 80 days. In contrast, at 5℃, the content did not change notably at any maturation stage regardless of the experimental period. The changes in the carotenoid content and gene expression suggest that carotenoid accumulation during on-tree maturation continues after harvest at 20℃, but not at 5℃. The present results suggest that β-cryptoxanthin content will not decrease at a range from 5 to 20℃ irrespective of the maturation stage. Moreover, at 8℃ and above, the β-cryptoxanthin content will gradually increase, and the rate will be more rapid in fruit harvested when carotenoid accumulation is in progress on the tree.