The effects of controlled freezing-point storage on the postharvest quality of satsuma mandarin

Present study introduced a controlled freezing-point storage (CFPS) technique for the postharvest storage of satsuma mandarin (Citrus unshiu Marc. cv. Miyagawa Wase), with the environment temperature of −2°C during the whole storage period. The postharvest loss and quality changes of satsuma mandarin were investigated. According to the results, CFPS completely prevented fruit decay in the 90 days storage and the following shelf period without causing fruit chilling injury. In comparison, the decay rate of fruit stored at 10°C increased with the elongation of storage time, and reach to 6.67% after 90 days storage, then further increased to 33.33% after transferring to the shelf. CFPS significantly reduced the incidences of calyx browning, completely prevented fruit puffing, alleviated the decreases of citric acid, fructose and glucose in the long-term storage and the following shelf life of satsuma mandarin, compared with the 10°C storage. But CFPS alleviated the postharvest rind color development of satsuma mandarin, leading to paler rind color compared to the 10°C storage group. Both 10°C storage and CFPS group showed significant decrease of total aroma volatiles contents in the pulp after more than two months’ storage. But most of the volatiles, including all of the monoterpenes and aliphatic alcohols, as well as part of the monoterpenes derivatives and aliphatic aldehydes, rebound after being transferred to the 20°C shelf, with the extent much higher in 10°C storage group than that in CFPS group. In the shelf-life, the total volatile content of the 10°C storage group was about 2 fold that of the newly-harvested fruit, but the volatiles of the CFPS group were more similar to the newly-harvested fruit in content and composition. Correspondingly, the consumer's sensory evaluation results showed that the fruit of CFPS group was slightly sourer and with better typical mandarin flavor than those stored at 10°C. Comprehensively, CFPS was applicable in reducing the postharvest loss and alleviating quality deterioration in the long-term storage of satsuma mandarin.