UV-blocking and mechanically reinforced starch films incorporating Ce-UiO-66 nanoparticles for food packaging applications

Hazardous ultraviolet (UV) radiation found in sunlight can seep into food packaging and cause unfavorable physicochemical changes in food items. This study aimed to develop starch-based polymeric biofilms with UV-blocking capability by incorporating CeUiO-66 metal-organic framework nanoparticles (Ce66 NPs). These nanoparticles were synthesized <i>via</i> a solvothermal method using formic acid as a modulator. A Box-Behnken design was used to optimize modulator concentration, reaction temperature, and time to maximize surface area and yield. Under optimal conditions, Ce66 NPs exhibited high crystallinity, an average particle size of 287 nm, a large surface area (832.20 m² g^-1), and a yield of 66.25%. The Ce66 NPs were incorporated into starch films (SCe<i>x</i>, <i>x</i> = 0.5-3.0 wt%) <i>via</i> solution casting using glycerol as a plasticizer in an acetic acid medium. Although the addition of Ce66 NPs reduced film transparency, it significantly improved UV-blocking efficiency. Specifically, the SCe1 film blocked 83.5% UVA, 95.6% UVB, and 100% UVC radiation. Water vapor permeability decreased to 1.69 g mm m^-2 d^-1 kPa^-1, and solubility dropped to one third compared to the control film. The tensile strength also increased from 2.2 MPa to 8.4 MPa. Moreover, Ce66 NPs exhibited notable photocatalytic activity, degrading up to 65% of RR195 dye under visible light. This dual functionality underscores the potential of Ce66 NPs for developing multifunctional biofilms for food packaging and environmental treatment.