Abstract: In order to clarify the effects of precooling treatments on the postharvest storability and neohesperidin metabolism of sweet cherries, forced-air precooling, ice-water precooling, cold storage precooling and ozone ice-water precooling were used to treat ‘Red Agate’ sweet cherries prior to being stored at (0.0 ± 0.5) ℃. The sensory quality, nutritional quality, respiratory metabolism, disease resistance-related enzyme activities, neohesperidin content and related gene expression in sweet cherries were analyzed during storage. In addition, the key indicators for the evaluation of storability and the key regulatory genes of neohesperidin metabolism in sweet cherries were selected by correlation analysis. The results showed that compared with commercial precooling (cold storage precooling), forced-air precooling significantly increased the activities of peroxisome (POD), superoxide dismutase (SOD), catalase (CAT), cinnamic acid-4-hydroxylase (C4H), cinnamyl-alcohol dehydrogenase (CAD) and 4-coumarate:coenzyme A ligase (4-CL), maintained higher fruit hardness, and reduced the disease index, dry fruit stem incidence, and browning index of sweet cherry during storage (P < 0.05), but its effect in promoting neohesperidin synthesis was not significantly different from that of ice water precooling (P > 0.05). VC content, and the activities of C4H, CAD and 4-CL (key enzymes in the phenylpropane metabolic pathway), SOD, PPO and lipoxygenase showed a significant correlation with the sensory quality of sweet cherries, which could be used as key physiological indicators to evaluate the storage stability of sweet cherry. The content of neohesperidin in sweet cherries fluctuated and decreased during storage. Forced-air precooling could promote neohesperidin synthesis by improving the gene expression of LOC110760277, LOC110751411, LOC110757814, QXJJ01001021, LOC110745765 and LOC110756675 and inhibiting the gene expression of LOC110758277 and LOC110771557. These results indicated that forced-air precooling was more effective in improving the storage storability of sweet cherries and promoting neohesperidin synthesis than ice-water precooling, cold storage precooling and ozone ice-water precooling.

Key words: precooling; sweet cherry; storability; neohesperidin; correlation analysis