Reducing postharvest pericarp browning and preserving health promoting compounds of litchi fruit by combination treatment of salicylic acid and chitosan

Abstract

Litchi (Litchi chinensis Sonn.) is one of the important fruit crops of the subtropical region. The fruit is highly perishable in nature and losses its commercial value within 1–2 days after harvest due to pericarp browning and deterioration in fruit quality. In the present study, effect of postharvest treatment with salicylic acid (0.5mM and 1.0mM) and chitosan (2%) on reducing pericarp browning and preserving functional and sensory quality of litchi fruit was investigated. Physiologically mature litchi fruits (cv. Purbi) were treated with salicylic acid (0.5mM and 1.0mM) and chitosan (2%) alone or in combination by dipping method for 5min. Following treatments, fruits were air-dried and stored at 4°C for 6 days. The results showed that among the applied treatments, salicylic acid (1.0mM) in combination with chitosan (2%) was highly effective in reducing pericarp browning, weight loss, decay loss and maintaining higher anthocyanins, phenolics, flavonoids, ascorbic acid and antioxidant capacity than control fruits. This treatment showed 1.4-fold lower pericarp browning, 1.6-fold lower weight loss and 6.7-fold lower decay loss than control. It also maintained 88% higher anthocyanin, 47% higher total phenolics, 29% higher total flavonoids and 35% higher total antioxidant capacity than control fruits. It also delayed increase in total soluble solids content in litchi fruit during storage. There was no significant effect of treatments on titratable acidity during storage but ascorbic acid content was maintained higher in treated fruits. Thus, combination treatment of 1.0mM salicylic acid and 2% chitosan can be used to reduce pericarp browning and preserving quality of litchi fruit during postharvest storage.