Sustainable chitosan nanocomposite films reinforced bio silica for UV protective and active food packaging

Chitosan was integrated with rice husk-derived bio-silica nanoparticles, including both silica-based nanocellulose (NC) and pure silica nanoparticles (SiO₂), to develop environmentally friendly active packaging films designated as CS@NC-SiO₂, valorizing agricultural waste within a circular-economy framework. The bio-silica Particles were prepared by citric-acid pretreatment followed by calcination at 600 °C. Films containing 0.25-1 wt% SiO₂, with and without NC, were systematically evaluated, and both the nanoparticles and the resulting nanocomposites were characterized by SEM, EDX, TEM, FTIR, and XRD. The optimized CS@NC-SiO₂ film, loaded with 0.75% SiO₂, exhibited marked improvements in several key properties. It recorded char residue 51% at 700 °C (compared with 39% for pure chitosan). The water contact angle increased to 94.6°, and water-vapor permeability fell to 1.146 g/(h·m·atm). it showed better mechanical properties than the pure chitosan film: tensile strength rose to 25.37 MPa, elongation at break to 27%, and Young's modulus to 593 MPa. The same film provided strong UV protection (UPF 57.8% (3.0% UVA and 1.8% UVB transmission) and showed high antibacterial activity (98.12% inhibition of Escherichia coli and 61.70% inhibition of Staphylococcus aureus. The CPS⁺ accelerated weathering tester was used to evaluate the performance of the fabricated films under UV irradiation and to assess their impact on the shelf life and weight stability of cherry tomatoes. fabricated films under UV irradiation and to assess their impact on the shelf life and weight stability of cherry tomatoes. The results revealed that the CS@NC-SiO₂ film limited cherry tomato weight loss to 16.12% after 21 days of storage versus 31.74-71% for the other formulations, while effectively acting as UV The formulations acted as effective UV blockers and provided active antimicrobial properties, successfully preserving the quality of the packaged cherry tomatoes for up to 21 days. This work delivers sustainable, low-cost active packaging films with strong potential for food preservation.Clinical trial number : Not applicable.