High-toughness chitosan-based films fabricated by crosslinking via Mannich multicomponent reaction for strawberry preservation.

Chitosan-based films suffer from issues such as poor plasticity and inadequate barrier properties. Herein, high toughness chitosan-based films were fabricated by chemical crosslinking between chitosan with acetoacetylated poly(vinyl alcohol) via the Mannich multicomponent reaction. The structure and properties of the resulting chitosan-based composite films were comprehensively investigated by methods such as FT-IR analysis, acid treatment, tensile testing and so on. The results demonstrated that the constructed network structure significantly enhanced the mechanical performance of the films with a tensile strength of 74.4 MPa and an elongation at break of 102.7%. Especially, the toughness of chitosan-based composite films reach up to 67.6 MJ/m3, which is much higher than those reported in the literature. Meanwhile, these films exhibited low oxygen and water vapor permeability coefficients of 8.6 × 10-6 and 4.5 × 10-6 mol·mm·m-2·d-1·kPa-1, respectively. Application in strawberry preservation demonstrated that the films effectively regulated the micro-environment, extending shelf life by 6 days. This study provides a sustainable and efficient strategy for designing high-performance bio-based packaging films for strawberry preservation.