Smart Active Packaging With Full‐Cycle Adaptability: Light‐Enhanced, pH‐Switchable Nanozyme Films for Fresh‐Cut Salmon Preservation

Fresh‐cut Atlantic salmon fillets are highly susceptible to microbial contamination and lipid oxidation. To address this, a smart, biodegradable active packaging film (SKP‐YCu‐CDs) was developed by incorporating yuzu peel‐derived, copper‐coordinated carbon dots (YCu‐CDs) into a ternary sodium alginate/konjac glucomannan/polyvinyl alcohol (SA/KGM/PVA) matrix. The resulting film exhibits excellent UV and water vapor barrier properties, high wet‐state ductility (elongation at break >300%), and a unique “water‐triggered peelable” interface for clean, zero‐residue removal before cooking. Crucially, the embedded YCu‐CDs act as a pH‐adaptive, near‐infrared (NIR) light‐enhanced nanozyme system synchronized with salmon spoilage stages. During early acidic phases caused by bacterial metabolism, NIR irradiation amplifies a peroxidase‐like oxidative burst, killing 76.33% of Staphylococcus aureus and 64.69% of Escherichia coli . As protein degradation shifts the microenvironment toward neutrality later on, the nanozymes transition into an antioxidant state to scavenge free radicals and inhibit lipid rancidity. Salmon‐fillet preservation experiments demonstrated that this bifunctional coating effectively suppresses biochemical deterioration, maintains myofibrillar structures, and extends salmon shelf life by at least 4 days. With excellent biocompatibility, this advanced material offers a safe, full‐cycle preservation strategy for high‐value aquatic products.