Lysozyme-Functionalized PVA/CMC/β-Cyclodextrin/Pectin Hydrogel Films for Strawberry Preservation and Flexible Sensing

A multifunctional hydrogel film, denoted as PCDGPL, was developed for strawberry preservation, and its prospective flexible-sensing capability was evaluated. Distinct from previous systems centered on colorimetric freshness indication or chemically/photocrosslinked sensing networks, PCDGPL employs a physically crosslinked, freeze-thawed PVA/CMC/pectin/β-CD matrix to couple lysozyme-associated antibacterial preservation with NaCl-enabled tensile and compressive deformation responses; a full-formulation-minus-β-CD control further isolated the network-modulating contribution of β-CD. The hydrogel network was proposed to be stabilized by freeze-thaw-induced PVA physical junctions, together with multiple hydrogen-bonding interactions among CMC, pectin, and β-cyclodextrin. Glycerol improved flexibility and moisture retention, NaCl provided ionic conductivity, and lysozyme incorporation contributed to the antibacterial activity of the film. The optimized PCDGPL film showed balanced mechanical properties, stable cyclic tensile/compressive behavior, and reliable strain-dependent resistance responses under stretching and compression. It also exhibited effective antibacterial activity against Escherichia coli and Staphylococcus aureus with good cytocompatibility. In strawberry preservation tests, PCDGPL reduced weight loss to approximately 2.5% and decay rate to 15%, while maintaining approximately 97% of the initial firmness after 10 days. This work provides a promising hydrogel-based active packaging platform for strawberry preservation, together with a prospective capability for mechanical deformation sensing.