A pullulan/sodium carboxymethyl cellulose film incorporated with cinnamaldehyde-loaded nano-emulsions: Preparation, characterization, and application in blueberry preservation.

The environmental impact of petroleum-based food packaging has driven growing interest in biodegradable and functionally active alternatives. This study developed a novel bioactive composite film by incorporating cinnamaldehyde nano-emulsions (CIN-NEs) into a pullulan (PUL)/sodium carboxymethyl cellulose (CMC) matrix. The film's functional properties were evaluated. SEM, FTIR, and XRD analyses confirmed the excellent compatibility between CIN-NEs and the PUL/CMC matrix, with all films displaying dense and uniform microstructures. The composite film incorporated with 12 % CIN-NEs (PCF-12) demonstrated a remarkable UV-blocking capacity. Specifically, it blocked over 99 % of UV radiation in the UVB (280-320 nm) and UVC (200-280 nm) regions, and more than 72 % in the UVA (320-400 nm) range. Furthermore, compared to the control film (PCF-0), PCF-12 exhibited improved flexibility, with the elongation at break increasing to 82.64 %. It also demonstrated enhanced water resistance, with the water contact angle increasing by 22.59°, while the moisture content and water solubility decreased by 3.17 % and 18.73 %, respectively. Combined with the reinforced antibacterial and antioxidant properties, the PCF-12 effectively extended the shelf life of blueberries to 8 days at room temperature, highlighting its potential for application in food packaging.