Post‐Harvest Spermine Treatment Improves the Shelf Life of Litchi ( Litchi chinensis Sonn.) Fruit Under Refrigerated Conditions

An experiment was conducted to improve the shelf life of litchi cv. Deshi by post‐harvest spermine treatment. Freshly harvested litchi fruit were dipped in 1.0–2.0 mM spermine solution for 1 min and stored in refrigerator at 8°C with 85%–90% relative humidity. Membrane permeability of fruit pericarp was recorded to 8.11% ± 0.55% after 29 days of storage in 1.0 mM spermine dipping; although it was recorded 21.06% ± 2.25% in control. Peroxidase and polyphenol oxidase activity in the pericarp were also reduced significantly after 29 days of storage in 1.0 mM spermine treated fruit (3.82 ± 0.48 and 14.33 ± 1.25 unit mg −1 protein, respectively with 27.26 ± 2.57 and 24.31 ± 1.78 unit mg −1 protein, respectively in control). However, catalase and phenylalanine ammonia‐lyase activity was improved by 1.84% and 24.83%, respectively, in this treatment after 29 days of storage as compared to respective control. Physiological weight loss and decay loss were also recorded minimum in this treatment after 29 days of storage (1.33% ± 0.06% and 3.06% ± 0.16%, respectively; while in control 6.78% ± 0.25% and 84.97% ± 4.20%, respectively) with maximum retention of anthocyanin on the fruit pericarp. Biochemical attributes of the fruit viz. total soluble solids, total sugars, ascorbic acid, total phenols, flavonoids content and antioxidant activity were also retained significantly after 29 days of refrigerated storage under 1.0 mM spermine treatment. Therefore, post‐harvest dipping of litchi fruit in 1.0 mM spermine solution followed by refrigerated storage at 8°C with 85%–90% relative humidity can be recommended for extending the shelf life of litchi fruit for 29 days which may help to get higher market price by avoiding market glut.