Matrine-incorporated chitosan active biofilms with enhanced barrier and antimicrobial properties for postharvest fruit preservation.

Biodegradable active packaging biofilms with multifunctional preservation performance have attracted increasing attention for postharvest fruit preservation. In this study, matrine-incorporated chitosan active biofilms were developed using a citric acid-assisted casting strategy to improve the barrier, antioxidant, and antimicrobial properties of chitosan-based biofilms. Structural characterization demonstrated that matrine formed intermolecular hydrogen-bonding and electrostatic interactions with chitosan, resulting in a denser and more homogeneous biofilm network. Under the optimized formulation (20% acetic acid, 4 mg/mL matrine, 15% citric acid), the composite biofilm exhibited significantly enhanced mechanical strength with tensile strength reaching 2.27 MPa, together with substantially reduced water vapor permeability (2.33 × 10-6 g·mm-2·Pa-1·h-1) and improved surface hydrophobicity as reflected by an increased water contact angle of 86.2°. The matrine/chitosan biofilms also demonstrated strong radical scavenging activity and potent antibacterial efficacy against Escherichia coli and Staphylococcus aureus, with minimum inhibitory concentrations as low as 0.30 mg/mL and 0.15 mg/mL, respectively, while maintaining excellent biocompatibility (cell viability >88%) and favorable biodegradability. Application studies demonstrated that the active biofilms effectively delayed water loss, microbial spoilage, browning, and quality deterioration of strawberries, cherries, blueberries, and grapes during ambient storage, thereby prolonging postharvest shelf life. The improved preservation performance was mainly attributed to the synergistic barrier, antioxidant, and antimicrobial effects of the composite biofilms. These findings suggest that matrine/chitosan active biofilms have considerable potential as sustainable biodegradable packaging materials for fruit preservation applications.