Biopolymer-enhanced nanoemulsions for controlled release of thyme: Impact on strawberry shelf life and quality

The development of natural, edible coatings is essential for enhancing postharvest fruit preservation while reducing reliance on synthetic preservatives. In this study, a multi-functional coating combining thyme-loaded nanoemulsion (Nano-EM-Thy) with chitosan (CH) and carboxymethyl cellulose (CMC) was formulated to extend the shelf life of strawberries. Water-in-oil nanoemulsions were prepared with the oil (containing medium chain triglyceride oil (MCT) with Thy), tween 80, and water (containing one or both biopolymers) at a mass ratio of 2:4:94 using a spontaneous emulsification method, achieving droplet sizes ranging from 60.45 to 106 nm. The nanoemulsion exhibited strong antimicrobial, effectively controlling Botrytis cinerea growth and maintaining fruit quality. Coatings containing Nano-EM-Thy, CH, and CMC significantly reduced weight loss (1.7 %), preserved firmness (3.6 N), and stabilized anthocyanin content over 15 days of storage at 4 °C. This composite coating extended the shelf life of strawberries by maintaining their physicochemical properties and reducing microbial spoilage, presenting a promising approach for natural postharvest preservation strategies. Highlights : • Nanoemulsions with chitosan and CMC control gray mold in strawberries effectively. • Combining thyme nanoemulsions with chitosan and CMC reduced fruit decay by 83 %. • Biopolymer coatings lowered weight loss in strawberries by 71 % during 15-day storage. • Nanoemulsions with chitosan and CMC retained over 50 % thyme after 7 days. • Edible coatings with chitosan and CMC maintained strawberry firmness and reduced spoilage.