A green, chemical crosslinker-ternary macromolecular film from soy protein, Camellia waste, and carrageenan via Maillard reaction for food preservation

Bio-based packaging films are promising alternatives to petroleum-based plastics, but their application is limited by chemical crosslinkers, high feedstock costs, and performance-sustainability trade-offs. Here, a crosslinker-free ternary film (SCC) was fabricated from soy protein isolate, Camellia oleifera cake extract (COCE), and carrageenan via Maillard-induced glycation. Under optimized conditions (95 °C, pH 8.5), Maillard covalent crosslinking formed a compact network, improving physicochemical properties. Compared with SC film, SCC showed a 4.4% lower swelling ratio, water vapor permeability of 2.019 × 10⁻¹² g·mm⁻¹·Pa⁻¹·h⁻¹, and enhanced tensile strength and compactness. DPPH and ABTS scavenging activities increased by 64% and 48%, respectively, and SCC exhibited potent antibacterial activity against E. coli and S. aureus. In preservation tests, SCC delayed moisture loss and ascorbic acid degradation in blueberries, retaining 51% of the initial vitamin C after 8 d. It also suppressed pH rise and metmyoglobin accumulation in pork, achieving 12% higher weight retention than the control. Moreover, the all-biomass SCC film degraded rapidly (78% weight loss in 14 d) in soil without toxic residues. This study demonstrates an effective strategy for high-value utilization of Camellia oleifera cake waste to develop sustainable food-packaging materials.