Abstract
The practical use of plant essential oils in postharvest fruit preservation remains challenging due to their physicochemical instability and rapid degradation under storage conditions. In this study, a chitosan-based nanogel modified with fatty acid was formulated to encapsulate thyme essential oil (TEO). The nanogel was synthesized using an emulsion-gelation method and characterized through Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Different coating treatments, including free TEO and TEO-loaded nanogels, were applied to Camarosa strawberries, which were stored at 4 °C for 16 days. FTIR analysis indicated hydrogen bonding interactions between chitosan and essential oil components, while SEM images confirmed a uniform and spherical morphology of the nanogels. The release profile of TEO exhibited a biphasic and sustained pattern. Application of the coating significantly reduced weight loss, maintained fruit firmness, and stabilized changes in total soluble solids (TSS), titratable acidity (TA), and pH. Furthermore, TEO-loaded coatings preserved anthocyanin and ascorbic acid contents and maintained a higher antioxidant capacity compared to the control group. Additionally, the coating suppressed the activity of polyphenol oxidase (PPO). In contrast, it significantly enhanced the activities of defense-related enzymes, including catalase (CAT) and peroxidase (POD), indicating an upregulated antioxidant defense system. Overall, the chitosan-based nanogel encapsulating thyme essential oil demonstrates high potential for extending the shelf life and preserving the postharvest quality of fresh strawberry fruits.