湿热条件下大豆分离蛋白与葡萄糖、麦芽糖的美拉德反应

研究湿热条件下反应温度、反应时间及混合质量比对大豆分离蛋白（soybean protein isolate，SPI）与葡萄糖、麦芽糖之间美拉德反应的影响，并对所得美拉德反应产物的溶解性、乳化性、溶液pH值、电势、热性能、结构和分子质量的变化进行表征。结果表明，SPI与2?种还原糖发生美拉德反应的最适条件为按质量比4∶1混合后在80?℃条件下反应6?h。美拉德反应明显改善了SPI的溶解度，并且麦芽糖比葡萄糖对SPI的改性效果更佳；美拉德反应降低了SPI的乳化性，并对其ζ电势有一定影响，随着美拉德反应程度的增加，SPI的负电荷明显减少；美拉德反应会使SPI溶液的pH值降低；热稳定性分析表明美拉德反应降低了SPI的热稳定性；傅里叶变换红外光谱分析表明美拉德反应在SPI中引入了新的化学键；荧光分析表明美拉德反应增强了SPI的荧光强度；十二烷基硫酸钠-聚丙烯酰胺凝胶电泳测定表明美拉德反应导致了大分子物质的形成。

Maillard Reaction of Soybean Protein Isolate with Glucose and Maltose under Wet Heating Conditions

The Maillard reaction has been reported to be capable of improving the functional properties of soybean protein isolate (SPI). In this work, the effects of temperature, reaction time and mixing ratio on the Maillard reaction between SPI and glucose/maltose were studied, and the changes in solubility, emulsifying activity, solution pH, ζ potential, structure and molecular mass of Maillard reaction products were measured. The results indicated that the optimum reaction conditions were determined as mass ratio between SPI and sugar 4:1, temperature 80 ℃ and duration 6 h. The reaction markedly improved the solubility of SPI and maltose was more effective than glucose in improving this parameter. The reaction reduced the emulsifying activity and affected the ζ potential of SPI. As the Maillard reaction proceeded, the negative charge carried by SPI decreased obviously. The Maillard reaction reduced the pH of SPI solution. Thermal analysis revealed that the modification decreased the thermal stability of SPI. Fourier transform infrared spectroscopy confirmed the introduction of new groups into SPI. Moreover, the Maillard reaction enhanced the fluorescence intensity of SPI. Sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) showed the formation of large molecules.