Effects of Postharvest Edible Coatings to Maintain Qualitative Properties and to Extend Shelf-life of Pomegranate (Punica granatum. L)

Regardless of the low respiration rate in pomegranate fruits, it is a greatly perishable product. An alternative to maintain quality and prolong the shelf life of pomegranate fruits could be edible coatings. In the present study, three different edible coatings including: 1% chitosan, 1000 mg L-1 thymol, and their combined were investigated on the postharvest quality of pomegranate fruits. Changes in weight loss, fruit firmness, total soluble solids (TSS), titratable acidity (TA), juice pH, anthocyanin, total phenolic, and flavonoids content, sensory characteristics and fungal decay incidence of fruits were evaluated during 30, 60, 90 and 120 days storage at 6 °C. The results showed that coated fruits with 1% chitosan + 1000 mg L-1 thymol significantly decreased weight loss and firmness than uncoated fruits. Furthermore, the coated fruits with 1% chitosan + 1000 mg L-1 thymol exhibited significantly higher anthocyanin, total phenolic, flavonoids content, and sensory characteristics than the control treatment. The minimum shelf-life (83.33 days) was observed in uncoated fruits, while the maximum shelf-life (108.33 days) was recorded in fruits coated with 1 % chitosan + 1000 mg L-1 thymol. Duration of storage had a significant effect on weight loss, firmness, juice pH, anthocyanin content, total phenolic content, flavonoids content, sensory characteristics, and decay, whereas there was no significant effect on TSS, TA, and TSS/TA. In conclusion, the combined application of chitosan and thymol can provide a useful alternative for shelf life extension of pomegranate fruits.