The effect of a variable initial pH on the structure and rheological properties of whey protein and monosaccharide gelation via the Maillard reaction

Abstract

Abstract The effects of varying the initial pH from 5 to 9 on Maillard reaction-induced whey protein gel formation and structural and rheological properties were determined. The molecular mass of whey protein and reducing sugar conjugates increased according to SDS-PAGE determination. Amino and surface sulphydryl groups were decreased, contributing to gel network formation. The amide I and II bands at 1640\xa0cm−1 and 1550\xa0cm−1, respectively, were decreased and the amide III peak at 1200–1300\xa0cm−1 increased, indicating the amino groups were participating in complex cascade reactions and the Maillard reaction during gel formation. Fluorescence measurements revealed that exposed tryptophan residues could increase the hydrophilic properties of the glycosylated protein. Gels formed from whey protein\xa0+\xa0glucose and from whey protein\xa0+\xa0xylose at an initial pH of 5 and 7, respectively, had a higher elastic modulus (G′), which was related to increased β-sheet and random coil formation after the Maillard reaction.