Abstract: The cuticle plays multiple important roles in the postharvest physiology of fruits. In this study, we examined the change of cuticle components during the postharvest cold storage of Satsuma mandarin (Citrus unshiu) and we also investigated their effects on the spore germination and mycelial growth of Penicillium digitatum. The results showed that the amounts of cutin and wax, the main components of cuticle, increased firstly and then decreased during cold storage and the amount of cutin changed more significantly. Free fatty acids were the most abundant wax components in the epicuticular wax. The amount of free fatty acids increased from 0.73 to 3.09 μg/cm2 over the first ten days of storage and then it decreased to 0.64 μg/cm2 on the 40th day. The most abundant wax components in the intracuticular wax were terpenoids and their content was fluctuated during the storage process. Cutin was mainly composed of cinnamic acid and hexadecanedioic acid. The content of cinnamic acid decreased gradually and reached the lowest level of 13.90 μg/cm2 on the 40th day, while the content of hexadecanedioic acid increased to 17.90 μg/cm2 on the 10th day and then decreased to 6.60 μg/cm2 on the 40th day. Results of in vitro tests showed that the spore germination could be inhibited by cutin and mycelial growth of Penicillium digitatum could be inhibited by intracuticular wax (P < 0.05). These findings reveal the biochemical basis of the change in the cuticle during storage and the effects of its components on the growth of Penicillium digitatum, which will provide an important basis for improving the storability of Satsuma mandarin.

Key words: Satsuma mandarin fruit, cold storage, cuticle, Penicillium digitatum