Abstract: Soybe protein isolate (SPI) /cellulose nanofiber (CNF)/ferulic acid (FA) composite films were prepared with different compositions and evaluated for tensile strength, elongation at break, water vapor permeability, oxygen permeability, moisture absorption capacity, transmittance, contact angle and antibacterial efficacy. The results showed that the performance of the composite film with the addition of 20.0 g of CNF and 0.4 g of FA was the best. Compared with pure SPI film, the tensile strength and contact angle of the composite film increased by 116.19% and 127.21%, and the moisture absorption was also improved. The elongation at break, water vapor permeability and oxygen permeability decreased by 59.76%, 90.91% and 77.55%, respectively and the transmittance also decreased significantly (P < 0.05). Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis showed that cross-linking with FA made the molecular structure of the protein denser, and strengthened the interaction between the CNF and protein molecules, imparting smother surfaces and flatter cross-sections to the composite film. The addition of FA could also increase the antibacterial effect of the composite film. This study will provide a technical reference for further research on soybean protein films and expand its application range.

Key words: soybean protein isolate; cellulose nanofiber; ferulic acid; scanning electron microscopy; Fourier transform infrared spectroscopy; X-ray diffraction