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

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.