Thermal, structural and mechanical characterization of bio-nanocomposite films from purple sweet potato starch/chitosan nanoparticles integrated with anthocyanin extract

• Development of bio-nanocomposite films integrating anthocyanins from purple sweet potato extract. • Enhanced film properties, including decreased water vapor permeability and increased tensile strength. • FTIR and XRD analyses confirm hydrogen bonding and improved structural properties. • Films demonstrate potential as intelligent packaging for monitoring food freshness. The development of active and intelligent packaging films using natural bioactive compounds has gained significant interest in food preservation. This study presents the fabrication and characterization of bio-nanocomposite films composed of purple sweet potato starch (PSPS) and chitosan nanoparticles (CH), reinforced with anthocyanin extract from purple sweet potato extract (PSPE). These films were designed to enhance mechanical strength, barrier properties, and antioxidant functionality for smart food packaging applications. FTIR analysis confirmed the formation of hydrogen bonding interactions between anthocyanins and the CH-PSPS matrix, indicating effective incorporation of bioactive compounds. The X-ray diffraction (XRD) analysis revealed a shift from semi-crystalline to an amorphous structure upon anthocyanin addition, particularly at 10 % and 15 % PSPE concentrations. These structural modifications significantly influenced the mechanical properties, with tensile strength increasing from 25.56 MPa to 43.96 MPa, demonstrating enhanced material durability. The water vapor permeability (WVP) was effectively reduced from 8.48 × 10⁻⁸ g·Pa⁻¹·s⁻¹·m⁻¹ to 4.89 × 10⁻⁸ g·Pa⁻¹·s⁻¹·m⁻¹, indicating improved barrier properties suitable for food packaging. Additionally, thermogravimetric analysis (TGA) confirmed an increase in thermal stability, making these bio-nanocomposite films promising for food packaging that requires resistance to environmental variations. The combination of mechanical reinforcement, improved barrier properties, and antioxidant functionality suggests that these films can serve as sustainable smart packaging materials, potentially extending the shelf life of perishable food products.