Impact of chitosan in combination with potassium sorbate treatment on chilling injury and quality attributes of pomegranate fruit during cold storage.

The impact of chitosan (CH) and potassium sorbate (PS) on quality attributes of pomegranate fruits (cv. Malas e Saveh) was evaluated during 90 days of storage at 4°C and 85%-90% relative humidity. The CH as well as the combined treatments (CH + PS) were effective in decreasing the chilling injury (CI) symptoms, electrolyte leakage, and malondialdehyde contents of fruit peel. Furthermore, CH, PS, and CH + PS treatments enhanced the activity of DPPH radical scavenging, and antioxidant enzymes of arils, and preserved the ascorbic acid content at high levels during the storage period. Fruits treated with CH1% + PS10% and CH2% + PS10% exhibited the lowest decay incidence and weight loss. Higher content of arils' phenols, flavonoids, and anthocyanin was observed in treated-fruits as a result of more activity of phenylalanine ammonia-lyase (PAL) and low activity of polyphenol oxidase (PPO). Consequently, CH + PS showed positive effects on the storage life of pomegranate fruits in terms of CI, decay incidence, and also nutritional values. PRACTICAL APPLICATIONS: Enhancement of chilling tolerance of pomegranate fruits during cold storage condition is a crucial issue. Application of CH coating alone or in combination with potassium sorbate could decrease the CI symptoms and preserved peel cell membrane integrity by maintaining electrolyte leakage (EL) and malondialdehyde in lower levels. Also, these treatments prevent weight loss and decay incidence in peel, and increase the activity of phenylpropanoid pathway and antioxidant systems in arils. All in all, usage of CH edible coating (2%) plus PS (10%) illustrated high efficiency in alleviating CI, decay incidence, and preserving nutritional quality of pomegranate fruits.