高乳化特性大米蛋白酶解产物的结构与性能研究

为了探究大米蛋白酶解产物中乳化性较好的关键组分，采用酸性蛋白酶、木瓜蛋白酶和胰蛋白酶限制性酶解大米蛋白，分析表面疏水性、二级结构、乳化活性及乳液稳定性以探究不同酶解产物结构特性和乳化特性的关系；筛选最优乳化特性样品后对其超滤分离得到<5 kDa、5~10 kDa和>10 kDa组分，通过界面张力、耗散型石英晶体微天平、粒径、微观结构及贮藏稳定性等指标，探究不同分子量肽的界面特性和乳液稳定性的关系。结果表明，胰蛋白酶酶解产物的得率最高；与大米蛋白相比，除水解度为6%的胰蛋白酶酶解产物外，其他酶解产物的表面疏水性均降低；酶解后β-折叠显著降低，蛋白结构更加舒展；胰2%具有较好的乳化性能；<5 kDa制备的乳液稳定性最差，贮存7 d后粒径由2.59 μm增加到7.82 μm；而>10 kDa组分界面张力较小，界面层较厚，具有较好的乳液贮藏稳定性，表明分子量较大的肽更能有效地稳定乳液。

Study on Structure and Properties of Hydrolyzed Rice Protein with High Emulsification Properties

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. <5 kDa, 5~10 kDa, and >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 <5 kDa-stabilized emulsions increased from 2.59 μm to 7.82 μm after 7 days storage. The result suggested that emulsion stabilized with <5 kDa had poor storage stability. >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.