Innovative Chitosan Edible Coating Incorporated With a Natural Deep Eutectic Solvent and Aloe vera for Extending the Blackberry Shelf Life

Abstract

Biodegradable and nontoxic chitosan edible coatings offer a promising alternative to conventional plastic food packaging materials. Recently, there has been significant interest in incorporating green plasticizers into these coatings. Accordingly, response surface methodology was employed to optimize a chitosan coating formulation that integrates Aloe vera extracts and a deep eutectic solvent (choline chloride–citric acid) as a plasticizer. The selection of the optimized formulation was related to quality characteristics of coated blackberries including their weight loss, pH, total phenolic content, total anthocyanin content, and antioxidant activity after 7 days of cold storage. The models demonstrated a high level of significance between the responses and independent variables, with p value less than 0.0001. The optimal coating formulation for blackberry fruits was identified as 2.05% (v/v) aloe rind extract, 1.1% (w/w) aloe gel extract, and 15% (w/w) choline chloride–citric acid. The developed film was characterized by ATR-FTIR and SEM for its intermolecular interactions and surface morphology, respectively, demonstrating good combability of polymer matrix with the plasticizer and aloe extracts. The optimized film was compared to a pure chitosan film in regard to their physical and mechanical properties. The alternative plasticizer choline chloride–citric acid improved the flexibility of the edible packaging by enhancing its mechanical properties, such as tensile strength, elongation at rupture, and elastic modulus. Additionally, the incorporation of this plasticizer and plant extracts slightly increased the transparency of the film. The coating was then applied to blackberry fruits in order to investigate the potential of the developed coating formulation to maximize the shelf life of food products. The results indicated the ability of the coating to extend shelf life and maintain the quality of the fruits.