Synergistic antimicrobial and barrier enhancement in chitosan-rhamnolipid composite films for postharvest fruit...

Microbial spoilage and physiological deterioration are the major causes of postharvest fruit losses and pose significant challenges to food quality and safety. In this study, a chitosan-based composite film incorporating rhamnolipids was developed as a biodegradable coating for postharvest fruit preservation. The incorporation of 0.3 g/L rhamnolipids increased the tensile strength and elongation at break of the chitosan film by 2.11 MPa and 17.61%, respectively. Compared with pure chitosan film, the composite film exhibited enhanced UV-blocking properties and a 7.38% increase in antioxidant activity. Furthermore, antibacterial activity against Staphylococcus aureus and antifungal activity against Aspergillus niger were improved by 17.05% and 43.02%, respectively. Application of the composite film effectively delayed quality deterioration in mangoes and grapes by reducing weight loss and malondialdehyde accumulation and by preserving fruit firmness and total soluble solids during storage. These results demonstrate that chitosan-rhamnolipid composite film is a promising coating for postharvest preservation, offering a sustainable strategy for improving fruit quality and extending shelf life.