Chitosan-based melatonin composite coating extended storage life of minimally processed pomegranate aril sacs

Minimally processed/fresh-cut produce, including pomegranate aril sacs, deteriorate rapidly during storage due to enzymatic browning reactions, accelerated ripening rate, and senescence resulting from the cutting process. Edible coatings have been shown to maintain quality and extend the shelf life of minimally processed horticultural produce by providing modified atmosphere conditions that reduce the rate of enzymatic reactions and metabolic processes during storage. Moreover, incorporating bioactive compounds into coating matrices helps maximise the coatings’ efficacy in maintaining the quality of minimally processed horticultural products. Thus, this study aimed to investigate the potential of chitosan-based melatonin (CH-MT) composite coating in maintaining the postharvest quality of fresh-cut pomegranate aril-sacs during storage. Pomegranate fruit (‘Wonderful’) with no physical defects were processed into aril sacs and subsequently, the following treatments were applied; CH; 1.5% (w/v), CH+0.1 mM MT, CH+0.4 mM MT, CH+0.8 mM MT, CH+1 mM MT and distilled water used as a control treatment. The treatment application was conducted by dipping the aril sacs into the solutions for 3 min, followed by air-drying. Aril sacs were then packaged into polyethylene terephthalate punnets, each consisting of 4 aril sacs in 5 replicates per treatment, and stored at 5°C with 85±5 RH for 21 d. Aril colour, weight loss, respiration rate, ascorbic acid content, anthocyanins, and browning index were monitored at 3-day intervals. Results showed that CH-MT treatment significantly (p<0.05) lowered the rate of weight loss and respiration, and maintained higher aril colour intensity (C*), ascorbic acid, and anthocyanin content. Moreover, browning was significantly inhibited in coated aril sacs compared to the untreated aril sacs. However, the efficacy of melatonin treatment in maintaining the quality of pomegranate aril-sacs was concentration-dependent, with CH+0.8 mM MT treatment showing the best results. Therefore, CH+0.8 mM MT treatment could be recommended to alleviate physiological disorders and maintain fresh-cut pomegranate aril sacs’ quality.