Effects of carboxymethyl cellulose coating enriched with bacteriostatic preparation on cold preservation of Nanfeng mandarin

To develop new preservative technology of Nanfeng mandarin, the effects of composite edible coating(based on CMC, extracts of Impatiens balsamina L., citric acid, sucrose esters, glycerin and calcium propionate) on postharvest fruit quality such as weight loss, soluble solids content, titratable acidity, ascorbic acid content were evaluated during cold storage at 4℃. The physiological and biochemical indicators such as activities of superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO), chitinase (CHT), β-1,3-glucanase (GUN) and phenylalanine ammonia-lyase (PAL) were also periodically assayed. The data suggested that the edible coating exhibited a beneficial impact on the overall quality of Nanfeng mandarin by reducing the moisture loss and fruit spoilage, maintaining the titratable acidity and ascorbic acid contents by comparing with the uncoated fruits. Further, the coating could effectively enhance the activities of SOD, POD, CHT and GUN. However, the activity of PPO in the fruit was not enhanced by the edible coating treatment. Compared with CMC coating, the composite film could reduce the decay incidence significantly with none risk to fruit quality.