In order to improve the mechanical properties, water resistance and barrier properties of rice bran protein (RBP) film, glycosylated RBP (RBP-G) film and RBP-G-chitosan composite (RBP-G-CS) film were prepared. The effects of the mass ratio of glucose to RBP and the mass ratio of RBP-G to chitosan on the mechanical properties of the films were investigated. The color, transparency, water resistance, water vapor permeability and thermal characteristics of RBP, RBP-G and RBP-G-CS films prepared under the optimal conditions were compared and analyzed. The structure of the films was characterized by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the mechanical properties of RBP-G film with a glucose to RBP ratio of 1:1 were obviously improved, and the tensile strength increased by 28.00% and the elongation at break by 33.13% compared with RBP film. RBP-G-CS film with a RBP-G to chitosan ratio of 1:1 had better mechanical properties, and its tensile strength and elongation at break increased by 197.33% and 84.42% compared with RBP film, respectively. The transparency, water resistance, barrier properties and thermal properties of RBP-G-CS film were significantly improved (P < 0.05). The structure of RBP-G-CS film was uniform and compact, owing to the strong hydrogen bonding forces. These results show that glycosylation modification can improve the performance of RBP film, and a good combination of modified RBP and chitosan can greatly improve the mechanical properties and water resistance of the film.

To improve the solubility, stability and bioactivity of rice bran protein (RBP) and its hydrolysates and to enhance their utilization as biological carriers, this study prepared binary nanoparticles composed of rice bran protein hydrolysates and gum arabic (GA) by taking advantage of the interaction between proteins and polysaccharides. Trypsin hydrolysate (R-t) and alkaline protease hydrolysate (R-a) of RBP were prepared and their physicochemical and structural properties were determined. Subsequently, each hydrolysate was combined with GA to prepare binary nanoparticles, which were characterized using intermolecular interaction analysis, transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The results showed that the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity of R-t and R-a were (72.82 ± 1.95)% and (66.83 ± 2.34)%, respectively, which were significantly higher than that of RBP. R-t-G nanoparticles with good stability were obtained at pH 1.4, R-t/GA ratio of 1:1 (m/m), and total polymer concentration of 4 mg/mL. R-a-G nanoparticles with good stability were obtained at pH 1.4, R-a/GA ratio of 1:2.5 (m/m), and total polymer concentration of 4 mg/mL. Electrostatic interaction played a significant role in the binding of R-t and R-a to GA, thereby stabilizing the structure of nanoparticles, and R-t-G exhibited a more stable system compared with R-a-G, with superior dispersion, thermal stability and a stronger crystal structure.