Characterization of antioxidant properties of soy bean protein-based films with Cortex Phellodendri extract in extending the shelf life of lipid

The objective of this study was to prepare food-contact films with desirable antioxidant properties. Extracts from Cortex Phellodendri, a Chinese traditional medicine, was used as antioxidants introduced into soybean protein (SPI)/nano-cellulose crystals (NCC) film matrix. The antioxidant properties of films incorporating Cortex Phellodendri extracts (CPE) were investigated. The SPI/NCC/CPE (SNE) films were also characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The results showed that CPE had good compatibility with SPI and NCC, and also had hydrogen-bonding interactions between them. Total phenolic content and the ability to remove DPPH of films with/without CPE were studied. Release tests were also conducted in 95% ethanol/water (v/v) food simulant to evaluate the applicability of the films. The results showed that the films could provide long-term protection of lipid simulant. The films were further evaluated as packaging for beef tallow. The peroxide value (POV) of the packaged lipid was measured after different storage times, and the POV values of lipid wrapped with PE, SPI and SNE films were compared. Lipid wrapped with SNE film had the lowest POV over the whole storage period, indicating the prepared films effectively retarded lipid oxidation.