Design and application of soy protein isolate films reinforced with Janus nanoparticles for active packaging of minced meat

This study aimed to develop active soy protein isolate (SPI)-based packaging films incorporating Janus nanoparticles (JNPs) to improve the shelf life of minced meat. JNPs were synthesized using carboxymethyl cellulose and beeswax-based hydrophobic carbon dots and incorporated into SPI films at 0.03, 0.05, and 0.1% (w/w). Films were characterized for microstructure, antibacterial and antioxidant activities, mechanical properties, color, release pattern, and UV-blocking properties. FTIR and FESEM confirmed the homogeneous dispersion of JNPs. SPI-JNP0.1% films exhibited improved tensile strength (15.2 MPa vs. 9.6 MPa in SPI film) and elastic modulus (175.7 MPa vs. 112.5 MPa in SPI film), with slightly reduced elongation (31.4% vs. 36.5% in SPI film). Release studies showed that JNPs diffusion into food simulants was concentration-dependent. Antibacterial tests revealed superior inhibition of Listeria monocytogenes. When applied to beef, SPI-JNP films (0.1%) reduced total mesophilic and psychrotrophic counts by 4.4 and 4.2 log₁₀ CFU/g after 9 days at 7 °C. These results highlight the potential of JNPs as functional nanofillers in biodegradable food packaging.