Composite coatings containing silk protein, chitosan, and Aloe vera for prolonging postharvest shelf-life of ghost chilli (Capsicum chinense)

Abstract

Ghost chilli (Capsicum chinense) is an indigenous variety of capsicum in the northeast region of India, which contains considerable amounts of vitamin C and antioxidants. The short shelf-life of the fruit causes significant postharvest losses, a major hurdle against supply chain resulting in financial losses for growers and suppliers. The primary goal of this study was to improve postharvest shelf-life of ghost chilli by applying composite coating formulations prepared from silk protein (SP), chitosan (CH), and Aloe vera gel (AVG). The coating on ghost chilli was applied by dip-coating method, and it extended the shelf-life of the coated fruits for up to 15 days during storage in ambient conditions. The result showed reduced weight loss in the coated fruit (less than 15%) compared to the uncoated control (almost 20%), maintained firmness, total soluble solids, and titratable acidity in the coated chilli (more than 15 N, 2% and 0.52%, respectively) compared to the uncoated control (6 N, 3%, and 0.42%, respectively). Moreover, the microbial counts in the SP/CH/AVG coated chillies was significantly less (1.5 log CFU/g compared to the uncoated control (almost 4 log CFU /g) after 15 days of ambient storage. The developed composite coatings can be effective alternative to synthetic wax based coatings for shelf-life enhancement of fruits and vegetables, however, future studies on toxicity of the developed coating formulation, cost analysis, etc. are needed for their future scale-up and commercialization.