Structure and physiochemical characteristics of whey protein isolate conjugated with xylose through Maillard reaction at different degrees

The purpose of this study is to prepare Maillard reaction products (MRPs) with both good emulsification and antioxidant activity, and the relationship between the Maillard reaction degree and structural changes of whey protein isolate (WPI) conjugated with xylose through wet-heating was explored. Browning intensity didn’t change while the free amino groups reduced significantly at the initial stage of Maillard reaction (MR). Amino acid analysis indicated that the lysine and arginine reduced significantly. The antioxidant property of the MRPs was significantly improved. The best emulsifying properties could be obtained in the middle degree of MR. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis illustrated that WPI and xylose formed high molecular weight conjugates. The circular dichroism spectra suggested that α-helix and random coil were increased while the β-sheet and β-turns were decreased after the MR. All of the MRPs exhibited a marked red shift in the maximum fluorescence intensity, indicating that the hydrophilicity of MRPs was enhanced.