Molecular structure and functional properties of glycinin conjugated to κ-carrageenan and guar gum: A comparative study

Molecular structure and functional properties of glycinin conjugated to κ-carrageenan and guar gum using a dry-heating method were comparatively analyzed. Glycosylation was confirmed by analyzing the degree of grafting, protein subunit composition, infrared absorption profile, and changes in contents of protein secondary structures. K-carrageenan was proven to possess a greater susceptibility to be grafted to glycinin than guar gum due to its relatively low molecular weight and negatively charged characteristics. The improvement of solubility by glycosylation with guar gum near the isoelectric point of glycinin was better than that by glycosylation with κ-carrageenan. Glycinin glycosylated with both polysaccharides exhibited enhanced emulsifying activity and stability. The enhanced apparent viscosity, elastic modulus, and viscous modulus also demonstrated that glycosylation promoted the appearance of stable elastic network structure. In summary, glycosylation with these two polysaccharides conferred glycinin superior emulsifying and rheological properties, and κ-carrageenan exhibited a better performance compared to guar gum.