The study firstly established oxidative stress injury model of human embryonic kidney cells (HEK293) by the induction of 2,2-azobis (2-methylpropionamidine) dihydrochloride (AAPH) to evaluate the antioxidant activity of five wheat protein-derived peptides Leu-Tyr (LY), Pro-Tyr (PY), Tyr-Gln (YQ), Ala-Pro-Ser-Tyr (APSY) and Arg-Gly-Gly-Tyr (RGGY). Then, it used quantum chemistry and molecular docking techniques to predict the optimal configuration and binding effect of five wheat protein-derived peptides combined with 2,2-azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS), and to explore the molecular mechanism of wheat protein-derived peptides. The results of cell test show that after the action of five wheat protein-derived peptides, the cell death rate significantly decreases to below 3.68% (P < 0.05), and the generation of reactive oxygen species (ROS) induced by AAPH was significantly reduced (P < 0.05), making the ROS content tend to normal levels. All five wheat protein-derived peptides show good total antioxidant capacity and free radical scavenging capacity of 1,1-Diphenyl-2-picrylhydrazyl (DPPH) (P < 0.05). RGGY shows the strongest total antioxidant capacity, with an activity value of (1.46 ± 0.08) mmol/L Trolox, followed by APSY, YQ, PY and LY. The DPPH free radical scavenging ability of YQ is the strongest, with a scavenging rate of 61.34% ± 2.24%, followed by APSY, RGGY, PY and LY. The results of molecular docking show that the CDOCKER interaction energy (-CIE) scores of the five wheat protein-derived peptides are 13.304 9, 13.397 3, 13.412 1, 16.768 5 and 16.268 3, respectively, which can effectively interact with ABTS, mainly through the formation of strong hydrogen bonds and hydrophobic forces between ABTS molecules to exert antioxidant activity.

The soy protein isolate was modified by adding different concentrations of tea polyphenols extract to prepare the oil-in-water (O/W) emulsion. The interfacial tension, interfacial protein adsorption fraction, emulsion particle size and zeta potential were investigated to explore the effect of tea polyphenols on the properties of soy protein isolate emulsion and interfacial protein displacement. The results show that the interfacial tension of soy protein isolate is increased after the addition of tea polyphenols. When soy protein isolate (1%, mass concentration) and soy oil are prepared into O/W emulsion with 9∶1 mass ratio by high-speed shear and ultrasound, tea polyphenols addition can improve the emulsion stability. Compared to the blank control group, when the amount of tea polyphenols added is 0.04%, the particle size of emulsion decreases significantly from 1.702 μm to 1.203 μm (P < 0.05), the protein adsorption fraction increases significantly from 9.22% to 20.68% (P < 0.05), and the zeta potential increases significantly from 25.7 mV to 27.1 mV (P < 0.05), respectively. Soy protein isolate shows resistance to bile salts displacement at the oil-water interface. In addition, the soy protein isolate modified by tea polyphenols is more difficult to be displaced by bile salts because of the strong electrostatic interaction and the thicker interface layer. Lipid digestion in intestine is an interfacial process. Exploring the interfacial displacement between protein and bile salts is beneficial to the study of lipid metabolism and food precise design.