College of Food Science and Engineering, Nanjing University of Finance and Economics/Collaborative Innovation Center for Modern Grain Circulation and Safety, Nanjing 210023, China.
College of Food Science and Engineering, Nanjing University of Finance and Economics/Collaborative Innovation Center for Modern Grain Circulation and Safety, Nanjing 210023, China.
Food Res Int. 2023 Feb;164:112317. doi: 10.1016/j.foodres.2022.112317. Epub 2022 Dec 9.
In this study, the effect of EGCG conjugation on the emulsifying and antioxidant properties of SPHs was investigated to improve the functional characteristic of soy protein hydrolysates (SPHs) and develop a novel hydrolysates/peptides-EGCG conjugates. Enzymatic hydrolyzed SPHs (DH 5%, 8%, 10%) covalent with 1% EGCG to prepare conjugates at pH 9.0. The free amino group and tryptophan content of SPHs-EGCG conjugates significantly decreased, indicating the successful preparation of SPHs-EGCG conjugates. Additionally, 5% SPHs-EGCG conjugates showed the highest EGCG binding capacity. EGCG conjugation increased the particle sizes and charge of SPHs. Compared with non-covalent SPHs, the covalent modification of EGCG increased the emulsifying and antioxidant capacity, especially for 5% SPHs-EGCG, it exhibited much higher surface hydrophobicity, ESI (emulsifying stability index), EAI (emulsifying activity index), and antioxidant activity than others. This result revealed that SPHs and EGCG played a synergistic effect in improving the emulsifying and antioxidant capacity. Fluorescence spectroscopy analysis showed that the combination of EGCG conjugation significantly decreased the fluorescence intensity and caused maximum emission red-shift. The formation of a covalent bond between SPHs and EGCG was verified through Fourier transform infrared spectroscopy (FTIR), and the results also showed a significant increase in the α-helix and random coil contents of the conjugation, and a significant decrease in the β-sheet and β-turn contents. These results indicate that EGCG conjugation with SPHs induced the unfolding and stretching of protein flexibility. Overall, SPHs-EGCG conjugates can be applied as a promising emulsifier to fabricate emulsion systems and would be helpful in designing functional beverages containing polyphenols and peptides with enhanced functional nutritional properties.
在这项研究中，研究了 EGCG 缀合对 SPHs 的乳化和抗氧化特性的影响，旨在改善大豆蛋白水解物（SPHs）的功能特性并开发新型水解物/肽-EGCG 缀合物。用 1%EGCG 将酶解 SPHs（DH5%、8%、10%）共价结合，在 pH9.0 下制备缀合物。SPHs-EGCG 缀合物的游离氨基和色氨酸含量显著降低，表明 SPHs-EGCG 缀合物的成功制备。此外，5%SPHs-EGCG 缀合物表现出最高的 EGCG 结合能力。EGCG 缀合增加了 SPHs 的粒径和电荷。与非共价 SPHs 相比，EGCG 的共价修饰增加了乳化和抗氧化能力，特别是 5%SPHs-EGCG，其表面疏水性、ESI（乳化稳定性指数）、EAI（乳化活性指数）和抗氧化活性均显著高于其他物质。结果表明，SPHs 和 EGCG 在提高乳化和抗氧化能力方面具有协同作用。荧光光谱分析表明，EGCG 缀合显著降低了荧光强度并引起最大发射红移。傅里叶变换红外光谱（FTIR）分析证实了 SPHs 和 EGCG 之间形成了共价键，并且缀合物的α-螺旋和无规卷曲含量显著增加，β-折叠和β-转角含量显著降低。这些结果表明，EGCG 与 SPHs 的缀合诱导了蛋白质柔韧性的展开和拉伸。总的来说，SPHs-EGCG 缀合物可用作有前途的乳化剂来制备乳液体系，并有助于设计含有增强功能营养特性的多酚和肽的功能性饮料。
