Abstract: In order to explore the effects of different precooling treatments on the postharvest preservation of ‘Lingwu Long’ jujube, harvested fruit were subjected to vacuum precooling, forced-air precooling or cold storage precooling before storage at (1 ± 1) ℃. Changes in the fruit quality and the activities of antioxidant enzymes in ‘Lingwu Long’ jujube were measured during storage. The results showed that compared with the untreated control, the three precooling treatments inhibited the mass loss and softening of jujube fruit, maintained the levels of soluble solids, titratable acids and ascorbic acid in jujube fruit, and effectively delayed the accumulation of malondialdehyde (MDA) and the increase in cell membrane permeability. Moreover, the precooling treatments enhanced ascorbate peroxidase, superoxide dismutase and catalase activities to stimulate the antioxidant defense system and in turn delay the oxidative browning and senescence. Particularly, forced-air precooling significantly inhibited the increase in MDA levels and cell membrane permeability, and inhibited lipid peroxidation of cell membranes to protect the cell structure. In addition, forced-air precooling maintained higher antioxidant enzyme activities, contributed to oxidative stress resistance and inhibited browning, hereby maintaining better storage quality. Principal component analysis further proved that forced-air precooling maintained higher storage stability and provided better preservation of jujube quality compared with vacuum precooling and cold storage precooling. In conclusion, forced-air precooling could effectively maintain the storage quality of jujube fruit and delay its ripening and senescence process.

Key words: ‘Lingwu Long’ jujube; precooling; quality; preservation