High-adhesion antimicrobial composite coating incorporating quaternary chitosan and tea tree oil for enhanced preservation of fruits and vegetables

This study developed high-adhesion quaternary chitosan coatings using amphiphilic HACC-oleic acid conjugates (HACC-OA) to enhance fruit and vegetable preservation. HACC-OA demonstrated improved viscosity and adhesion, providing a stable carrier for tea tree oil (TTO). The resulting TTO@HACC-OA coatings exhibited significantly reduced contact angle (43.7°) and increased retention amount on strawberry surfaces. Furthermore, TTO@HACC-OA demonstrated a lower volatilization rate of TTO (27.8 %) compared to pure TTO (49.5 %) and an enhanced synergistic antimicrobial activity (EC 50  = 1.51 mg/mL) against Botrytis cinerea Pers compared to HACC alone (EC 50  = 1.58 mg/mL). Preservation experiments revealed that TTO@HACC-OA effectively maintained color and firmness, reduced decay index and weight loss, delayed decline in vitamin C content of strawberries, postponed increase in total phenolic content, and mitigated malondialdehyde accumulation. Therefore, the prepared TTO@HACC-OA composite coating with excellent adhesion ability and preservation effect holds great potential for applications in fruit and vegetable preservation.