Effect of temperature and pH on the gelation, rheology, texture, and structural properties of whey protein and sugar gels based on Maillard reaction

Abstract This study aimed to determine the effect of initial pH and temperature on whey protein gel formation via the Maillard reaction, including changes in gel structure, rheological and texture properties. The color changes in the whey protein and glucose gels were not significant with increasing heat temperature. High temperature and alkaline conditions promoted exposure to hydrophobic groups such as –SH, which accelerated protein aggregation and gel formation. Moreover, the increased particle size and additional hydrophobic groups contributed to higher elastic modulus ( G ′) in the whey protein gel. Fluorescence measurements revealed that more tryptophan on the protein surface decreased with increasing temperature, which indicated that exposure to tryptophan could increase the hydrophobicity of the protein gels. Whey proteins formed stronger, gummier, more elastic, and more cohesive gels at 70 ℃ under initial pH 9 conditions, which also increased with the addition of fructose.