美拉德反应中乳清分离蛋白特性的变化

Changes in Physical and Chemical Properties of Whey Protein Isolate during Maillard Reaction

乳清分离蛋白(WPI)与两种还原糖(D-葡萄糖和D-半乳糖)按质量比1:1配制成混合液,分别在95℃条件下加热0～6h,得到不同反应时间的美拉德反应产物(MRPs)。测定MRPs的pH值、吸光度(A294nm和A420nm)、荧光强度、游离氨基含量以及蛋白聚合物变化趋势。结果表明:随着加热时间的延长,各反应体系的pH值显著降低(P<0.05);非荧光中间产物(A294nm)、褐变产物(A420nm)以及荧光强度显著增加(P<0.05);游离氨基的含量逐渐降低(P<0.05);SDS-PAGE测定表明,在美拉德反应过程中,α-乳白蛋白和β-乳球蛋白都发生了不同程度的聚合,生成更大分子的物质;WPI与D-半乳糖反应体系比D-葡萄糖体系反应产生的MRPs具有更多的中间产物和发生更大程度的褐变。

In this study,Maillard reaction products（MRPs） were prepared by heating 1：1（m/m） mixtures of whey protein isolates（WPI） with D-glucose or D-galactose at 95 ℃ for 6 h and sampling at different time points during the heating period for the determination of pH,absorbance at 294 nm and 420 nm（A294 nm and A420 nm）,fluorescence intensity,free amino group content and protein polymerization.The pH and free amino group content of each reaction system significantly（P0.05） decreased and the yields of non-fluorescent intermediate products（A294 nm） and browning products（A420 nm） and fluorescence intensity significantly（P0.05） increased with increasing heating time.SDS-PAGE analysis demonstrated that both α-lactalbumin and β-lactoglobulin could be polymerized to different extents into larger molecules.More intermediate products and higher degree of browning were generated from WPI-D-glucose system compared with WPI-D-glucose system.