Fabrication of Multifunctional Films Incorporating Purple Sweet Potato Anthocyanins and ZIF-8-NH2@Rt for Monitoring and Preservation of Pork Freshness

Natural antioxidants are limited in food packaging due to poor stability and compatibility. A multifunctional film was successfully prepared via the incorporation of functional fillers into a guar gum/polyvinyl alcohol (GP) matrix. ZIF-8 was amino-functionalized to enhance rutin (Rt) loading, and the resulting ZIF-8-NH2@Rt was combined with purple sweet potato anthocyanins (PSPA) to fabricate a composite film for pork freshness monitoring. Compared with neat GP, the ZIF-8-NH2@Rt/PSPA/GP film showed a 30.6% increase in tensile strength and an elongation at break of 36.6%. The composite film also imparted exceptional UV-blocking capabilities, with light transmittance plummeting to 3.22% in the UVA region, 0.40% in the UVB region, and 47.53% within the visible light spectrum. The films displayed significant antioxidant properties, with DPPH and ABTS scavenging activities recorded at 73.27% and 67.64%, respectively. During pork storage, the film exhibited stable color changes. The G/R values corresponding to the limit of edibility were determined to be 0.78 and 0.67 for storage at 25 °C and 4 °C, respectively. The film was reusable for four cycles and extended the shelf life of pork by at least one day. These findings highlight the film’s considerable promise in the realm of smart food packaging and dynamic freshness tracing.