College of Food Science, Northeast Agricultural University, Harbin, Heilongjiang 150030, China.
College of Food Science, Northeast Agricultural University, Harbin, Heilongjiang 150030, China.
Ultrason Sonochem. 2023 Nov;100:106645. doi: 10.1016/j.ultsonch.2023.106645. Epub 2023 Oct 10.
Herein, ultrasound-assisted conventional covalent binding methods (alkali treatment, free radical mediation, and an enzymatic method) were used to prepare soybean protein isolate (SPI)-(-)-epigallocatechin gallate (EGCG) conjugates to investigate the enhancement effect of the ultrasound synergistic treatment. In addition, the influence of EGCG grafting on the structure and properties of SPI was evaluated via reactive group analysis, spectral analysis, surface hydrophobicity measurements, emulsification property assessment, and α-glucosidase inhibition analysis. The obtained results revealed that the enzymatic method produced the highest polyphenol grafting content among the conventional techniques. Meanwhile, ultrasound treatment increased the amount of grafted polyphenol species during the alkali treatment and free radical mediation procedure, decreased the grafting efficiency in the enzymatic method, and maximized the grafting efficiency during the alkali treatment. In addition, reactive group and spectral analyses demonstrated that EGCG formed C-N and C-S bonds with SPI and decreased the α-helix content in the protein structure, thereby increasing the molecular flexibility of SPI. It also produced hydrogen bonds and hydrophobic interactions, as demonstrated by the results of molecular docking. Furthermore, the EGCG grafting of SPI conducted under the ultrasound-assisted conditions endowed SPI with unique functional characteristics, including good emulsification and antioxidant properties and high α-glucosidase inhibitory activity, while the ultrasound-assisted alkali treatment resulted in the optimal functional properties. The results of this study provide new insights into the effective preparation of SPI-EGCG complexes with multiple functionalities, thereby expanding the scope of high-value SPI utilization.
在此，采用超声辅助常规共价结合方法（碱处理、自由基介导和酶法）制备大豆分离蛋白（SPI）-(-)-表没食子儿茶素没食子酸酯（EGCG）缀合物，以研究超声协同处理的增强效果。此外，通过反应基团分析、光谱分析、表面疏水性测量、乳化性能评估和α-葡萄糖苷酶抑制分析，评估了 EGCG 接枝对 SPI 结构和性能的影响。研究结果表明，常规技术中酶法产生的多酚接枝含量最高。同时，超声处理增加了碱处理和自由基介导过程中接枝多酚的种类，降低了酶法中的接枝效率，在碱处理中最大程度地提高了接枝效率。此外，反应基团和光谱分析表明，EGCG 与 SPI 形成 C-N 和 C-S 键，降低了蛋白质结构中α-螺旋的含量，从而增加了 SPI 的分子灵活性。它还产生了氢键和疏水相互作用，这可以通过分子对接的结果来证明。此外，超声辅助条件下的 SPI-EGCG 接枝赋予了 SPI 独特的功能特性，包括良好的乳化和抗氧化性能以及高的α-葡萄糖苷酶抑制活性，而超声辅助碱处理则产生了最佳的功能特性。本研究结果为有效制备具有多种功能的 SPI-EGCG 复合物提供了新的思路，从而扩展了高附加值 SPI 的利用范围。
