Sustainable gelatin–carbon dot hydrogel coatings for fruit preservation: integrating antioxidant and antibacterial activities

To address key challenges in postharvest fruit preservation—namely microbial spoilage, moisture loss, and oxidative degradation—a multifunctional composite coating based on gelatin hydrogel embedded with carbon dots (Gel/CDs) was developed. In this system, the antioxidant and antibacterial properties of CDs were integrated into a hydrophilic and biocompatible hydrogel matrix, forming a protective layer with enhanced surface adhesion and interfacial compatibility. Under ambient storage conditions, the coating significantly delayed spoilage of strawberries and cherry tomatoes, prolonging their shelf life from 4 to 10 days. By integrating antimicrobial activity with intrinsic antioxidant capacity, the Gel/CDs coating demonstrates potential relevance for fruit preservation, including effective microbial control and retention of over 70% of the initial fruit weight. Its edibility and low toxicity confirm the coating's safety and suitability for food preservation, offering a residue-free alternative to chemical preservatives with strong potential for large-scale postharvest application.