Carboxymethyl Cellulose/Quaternary Ammonium Chitosan Composite Films Reinforced with Walnut Green Husk Extract–Loaded Calcium Carbonate for Pork and Strawberry Preservation

ABSTRACT Walnut green husk is typically discarded as waste. However, their valorisation holds significant potential due to the presence of bioactive compounds. This study aimed to enhance the value of this by‐product by developing biodegradable packaging materials. Initially, calcium carbonate particles loaded with walnut green husk extract (CA@WGHE) were prepared and subsequently incorporated into a carboxymethyl cellulose/quaternary ammonium chitosan (CMC/QAC) matrix to develop a composite film. The effects of CA@WGHE on the physicochemical, antioxidant and antimicrobial properties of the CMC/QAC film were evaluated, along with the impact of the composite films on the preservation of pork and strawberry. The addition of CA@WGHE significantly enhanced the CMC/QAC film's flexibility, hydrophobicity, UV‐blocking ability and its barrier properties against water vapour and oxygen. Specifically, the water vapour permeability and oxygen transmission rate of the CMC/QAC‐CA@WGHE15% film were reduced by 31.7% and 11.9%, respectively, compared to the pure CMC/QAC film. In addition, the CMC/QAC‐CA@WGHE films showed strengthened antioxidant activity and exhibited pronounced antimicrobial effects against Staphylococcus aureus and Escherichia coli O157:H7. The release of WGHE adhered to the Weibull model ( R 2 = 0.9785–0.9918), indicating a quasi‐Fickian diffusion mechanism. Preservation studies demonstrated that the CMC/QAC‐CA@WGHE films effectively inhibited microbial growth, slowed protein degradation and lipid oxidation in pork stored at 4°C. Additionally, the CMC/QAC‐CA@WGHE films significantly reduced softening, weight loss and the decline in total soluble solids, titratable acidity and vitamin C content in strawberries. This study provides a sustainable and cost‐effective solution for the value‐added utilisation of walnut green husk agricultural waste and the design of multifunctional bio‐based packaging films.