Corn starch-soy protein isolate films reinforced by metal-phenolic networks: Properties and application for...

The development of biodegradable and high-efficiency active packaging for food plays an important role in reducing environmental pollution and minimizing food waste. In this study, tannic acid‑iron metal phenolic networks (TA-Fe MPNs) were used to improve the properties of corn starch (CS)/soy protein isolate (SPI) films, with the aim of using them as active food packaging materials. FTIR spectroscopy, X-ray diffraction, and optical characterization of films confirmed that tannic acid and Fe³⁺ successfully formed TA-Fe MPNs inside the composite films. SEM images revealed that TA-Fe MPNs had good compatibility with the starch and protein matrix, leading to films with a dense microstructure. TA-Fe MPN crosslinking not only increased the tensile strength of the composite films by 96 % and reduced their water vapor permeability by 28 %, but also enhanced their thermal stability and UV barrier properties. Furthermore, the crosslinked films exhibited excellent antioxidant and antibacterial activities, which makes them an effective preservation effect on strawberries. In summary, this research offers novel insights that could facilitate the creation of high-efficiency active food packaging materials using metal phenolic networks as reinforcing agents.