Optimization and characterization of modified starch-chitosan composite films incorporated with Gongju extract

Active packaging film was prepared with acetylated distarch adipate (ADA), chitosan (CS) as material, and Gongju extract (GE) as an active additive. Through Response Surface Methodology (RSM), the optimal formula for the film was determined based on functional activity, barrier properties, and mechanical performance, yielding a composition of 2% (w/v) ADA, 1.3% (w/v) CS, and 1.25% (w/v) GE. The results indicated that the cross-linking interactions between ADA and CS can improve the barrier property of the film. Additionally, GE enhanced the flexibility of the film, reduced UV transmittance to approximately 5%, increased the antioxidant activity to over 90%, and significantly increased the antimicrobial activity. Rheological, SEM, FTIR, and XRD analyses confirmed good compatibility between the polymer matrix and the additive, with hydrogen bonding observed between them. Overall, this study systematically investigated the optimal formulation of ADA and CS incorporating GE, indicating that the prepared films hold great potential for use in active packaging applications. • The acetylated distarch adipate/chitosan (ADA/CS) blend film was first developed. • Gongju extract (GE) was applied in the field of active packaging for the first time. • The cross-linking effect of ADA and chitosan (CS) improved the barrier properties of composite films. • GE enhanced the flexibility, UV barrier capacity, and functional activity of composite films. • The optimum film formulation was: 2% (w/v) ADA, 1.3% (w/v) CS, and 1.25% (w/v) GE.