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In order to explore the key components affecting the emulsification characteristics in hydrolyzed rice protein. rice protein was hydrolyzed by acidprotease, papain and trypsin, respectively. The relationships between the structural and functional properties of different hydrolyzed rice proteins were studied by surface hydrophobicity, Fourier transform infrared spectroscopy (FTIR), emulsifying activity index and emulsifying stability index. 10 kDa were separated from the rice protein with degree of 2% treated with trypsin (trypsin 2%) by ultrafiltration. The interfacial tension, quartz crystal microbalance with dissipation (QCM-D), mean diameter particle, confocal laser scanning microscope (CLSM) and storage stability were measured to explore the influence of molecular weight on the interfacial characterization and emulsion stability. The results demonstrated that hydrolysates treated with trypsin exhibited the highest yield. Compared with the rice protein, the surface hydrophobicity of the enzymatic hydrolysis products declined significantly except for the rice protein with degree of 6% treated with trypsin (trypsin 6%). The secondary structure content revealed that the β-sheet contents of hydrolyzed rice protein significantly decreased, showing that the structure of hydrolyzed rice protein was more unfolded. The trypsin 2% exhibited the better emulsifying capacity. The mean diameter particle of 10 kDa had lower interfacial tension and thicker interfacial film than the others. The emulsion prepared by >10 kDa exhibited better emulsion stability. The results indicated that the emulsion stabilized by high molecular peptides was more stable than the smaller ones.

Curcumin exhibits antioxidant and antitumor properties, but its poor chemical stability limits its application. Insoluble peptide precipitates formed by proteolysis of rice glutelin are usually discarded, resulting in resource waste. The coupled treatment of heat-assisted pH shifting and compounded chitosan (CS) was used to fabricate rice peptide aggregate–chitosan complexes (RPA–CS). The structure, interfacial behavior, emulsion properties, and digestibility of curcumin-loaded RPA–CS Pickering emulsions were investigated. Increasing the CS concentration led to lower interfacial tension but larger particle size, and the three-phase contact angle of the RPA–CS complexes approached 90°. Quartz crystal microbalance with dissipation (QCM–D) indicated that RPA–CS complexes with 6 g·kg−1 of CS (RPA–CS6) had the highest K1 (0.592 × 106 Hz−1) and K4 (0.487 × 106 Hz−1), suggesting that the softest interfacial layers were formed. The solid–liquid balance of RPA–RPA–CS emulsions was lower than 0.5, declaring that they had more elastic behavior than that of RPA emulsions. RPA–RPA–CS4-and RPA–CS6 emulsions had better storage stability, lower FFA release (79.8% and 76.3%, respectively), and higher curcumin bioaccessibility (65.2% and 68.2%, respectively) than RPA emulsions. This study showed that a low-value insoluble rice peptide precipitate could be used as a valuable emulsifier in foods, which may increase the economics and sustainability of the food supply.