Abstract: In this study, soybean protein isolate (SPI), polyvinyl alcohol (PVA) and nanocellulose (NCC) were selected as the main raw materials to prepare nanocomposite films. Based on tensile strength, elongation at break, water vapor permeability, oxygen permeability, carbon dioxide permeability and light transmittance, the optimum preparation conditions were obtained using single factor experiments as follows: SPI concentration 3.0%, ratio of PVA to NCC 1:2, ultrasonic power 40 W, sonication time 20 min, and temperature 60 ℃. The as-prepared composite film had good packaging properties. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM) and contact angle analysis showed that the surface of this film was smoother and its internal reticular structure was denser than that of pure SPI film and the composite film without ultrasonic treatment. The ultrasonic-treated composite film could effectively maintain the hardness, moisture, soluble solids and VC contents of cherry tomatoes during storage, thereby extending its shelf life, indicating that this nanocomposite film, with excellent packaging performance, has potential application prospects in the preservation of fruits and vegetables.

Key words: soybean protein isolate; polyvinyl alcohol; nanocellulose; ultrasonic treatment; preservation of cherry tomatoes