Preparation of amphiphilic chitosan incorporated with ursolic acid active coating films and its delay of postharvest papaya fruit ripening

Amphiphilic chitosan (DA-CS-AG) was synthesized and incorporated with ursolic acid (UA) to develop an active coating film. Characterization techniques confirmed the preparation of DA-CS-AG, and UA was successfully entrapped in the active coating films. With the weight ratios of UA to DA-CS-AG increasing from 1:20, 2:20–4:20, the coating films exhibited increased thickness, improved water resistance, higher tensile strength, and enhanced antioxidant and antibacterial properties. As the UA/DA-CS-AG weight ratio increased from 1:20–2:20, the films ’ UV-shielding capability, water vapor barrier properties, and elastic properties increased. However, these properties deteriorated when the weight ratio increased to 4:20. Preservation experiments of papaya fruits demonstrated that UA/DA-CS-AG-2 coating films delayed the ripening of papaya at 25 º C for 16 days based on appearance, color changes, quality indexes, and sensory evaluation. In conclusion, these active coating films can serve as packaging materials for fruits and vegetables.