响应面优化豌豆分离蛋白-木聚糖轭合物的制备及结构功能研究

采用响应面法优化豌豆分离蛋白(PPI)-木聚糖轭合物的制备条件，并对所得PPI-木聚糖轭合物的结构性质和功能特性进行研究。结果表明，PPI-木聚糖轭合物的最佳制备条件为：溶液pH 8.15、加热温度60℃和反应时间160 min;在此条件下，轭合物的接枝度为60.92%。电泳分析结果表明，木聚糖被接枝到PPI分子上，表现为比原蛋白更大的分子质量；红外光谱分析结果表明糖基化改变了PPI的二级结构；内源荧光光谱结果表明PPI的三级结构受到改变，降低了荧光强度。相较于原蛋白，轭合物的溶解度得到显著改善，在pH 4时的溶解度从3.26%提升到9.08%;在pH 5时的溶解度从2.10%提升到7.63%。糖基化产物轭合物的乳化性能也明显提升，乳化活性指数从20.97 m²/g提高到40.23 m²/g;乳化稳定指数从11.23 min提升到65.51 min。

Optimization of preparation conditions of pea protein-xylan conjugate using response surface methodology and its structural and functional properties

The preparation conditions of pea protein isolate (PPI)-xylan conjugate optimized by the response surface methodology and the corresponding structural and functional properties were investigated in this study. Results showed that the optimal preparation conditions were as follows: sample solution pH 8.15, heating temperature 60 °C, and incubation time 160 min, under which the degree of grafting of the obtained conjugate was 60.92%. The electrophoretic analysis confirmed the formation of conjugate based on the appearance of protein band with high molecular weight. The changes in infrared absorption indicated the grafting of xylan chains changed the secondary structure of PPI. The intrinsic fluorescence results reflected the tertiary structure of PPI was changed to reduce the fluorescence intensity. Compared to the native PPI, the PPI-xylan conjugate exhibited an enhanced solubility. For instance, the solubility was increased from 3.26% to 9.08% at pH 4 and from 2.10% to 7.63% at pH 5. The emulsifying properties were also improved according the increase in the emulsifying activity index from 20.97 to 40.23 m2/g and the emulsifying stability index from 11.23 to 65.51 min.