Snakehead fish (Channa argus) skin protein-based antioxidant films enhanced by fish skin protein/rosmarinic acid/curcumin self-assembled nanospheres

The development of sustainable and high-performance food packaging materials is crucial for addressing global food waste and environmental pollution issues. An innovative approach was proposed by using fish skin protein (FSP) from Channa argus as a natural carrier to promote the self-assembly of rosmarinic acid (RA) and curcumin (CUR) into stable nanospheres (FSP/CUR/RA) through non-covalent interactions such as hydrogen bonds, π-alkyl/π-anion interactions, and electrostatic interactions in this study. Compared with binary systems, the self-assembled FSP/CUR/RA ternary nanospheres exhibited significant advantages in colloidal stability and functionality: the optimized RA6 nanospheres have the smallest particle size (508 ± 19.30 nm), the highest ζ-potential (13.04 mV), and excellent antioxidant activity (ABTS⁺ scavenging rate of 87.91 % at 20 μL), effectively overcoming the limitations of poor solubility and instability of CUR and RA. Upon incorporating the nanospheres into the active film, its overall performance was significantly enhanced. Specifically: Barrier properties were improved, with the water vapor transmission rate reduced to 4.06 × 10⁻¹³ g m⁻¹·Pa⁻¹·s⁻¹, representing a 27.6 % decrease compared to the pure FSP film. Mechanical properties were optimized due to RA's effective inhibition of CUR aggregation, achieving a well-balanced tensile strength (TS) and elongation at break (EAB). The film demonstrated outstanding antioxidant capacity, with a free radical scavenging rate of 86.39 %, significantly higher than the control groups. Multifunctional characteristics were evident, including ultraviolet shielding capability, controlled release of CUR/RA, and complete biocompatibility (cell viability 100 %). In practical applications, FSP/CUR/RA films significantly extended the shelf life of fresh shrimp by reducing weight loss (3 % compared to 4.44 % in the control group), maintaining a low TVB-N level (11.84 mg/100 g after 3 days), and inhibiting lipid oxidation (TBARS < 1 mg MDA/100 g). This study not only provided a sustainable strategy for the value-added utilization of fish processing by-products but also promoted the design of multifunctional food packaging materials with enhanced preservation capability.