Enhancing grape preservation: The synergistic effect of curry leaf essential oil in buckwheat starch-chitosan composite coatings

Abstract

A novel edible composite coating composed of buckwheat starch (BS) and chitosan (CH) with varying levels of curry leaf essential oil (CLEO) was synthesized in the present study. Initially, starch was extracted from buckwheat groats, and its proximate analysis revealed a high amylose content (21.91 ± 0.32%), which makes it an excellent base material for coating formation. The composite coatings were created by blending BS and CH with CLEO in different concentrations. The coatings underwent a comprehensive evaluation, including physico-chemical, functional, thermal analyses, and microstructural characterization. Cytotoxicity tests on human cell lines (Caco-2) confirmed that the coatings were non-toxic. Among the various formulations, the coating with 2.0% CLEO (referred to as F5) exhibited the highest antimicrobial activity, maximum antioxidant properties, and the lowest water solubility. Following this, the coatings were applied to green grapes (Vitis vinifera) via dip coating technique. The performance of coatings was assessed by storing the grapes under room temperature (25 ± 1 °C) and refrigeration conditions (4 ± 1 °C). From visual appearance and physio-chemical tests, it was concluded that the F5 coating was potentially active in extending the shelf life of grapes to 12 days at room temperature and to 20 days under refrigeration storage. Overall, the BS-CH-CLEO composite coating emerges as a refined and eco-conscious bioactive packaging solution, elegantly extending the shelf life of grapes while providing both sustainability and cost-efficiency.