Structural Characterization and Emulsifying Properties of Casein-Polysaccharide Covalent Complexes

To develop high-quality emulsion stabilizer, covalent complexes of casein-konjac glucomannan (CS-KGM_MRPs) and casein-oat β-glucan (CS-OG_MRPs) were prepared using the moist-heat method. The structure characteristics and properties of these complexes were investigated by infrared spectroscopy, endogenous fluorescence spectrum, SDS-PAGE, microstructure, rheological properties, thermal stability, and emulsification properties. The results demonstrated that the color of caseins glycosylated with KGM or OG was light brown, while the CS-OG_MRPs group exhibited darker coloration. Infrared spectroscopy, fluorescence spectroscopy and SDS-PAGE analysis indicated that KGM or OG underwent covalent reactions with casein, and the microstructure of the covalent complexes was significantly changed, resulting in a notable increase in surface porosity and the formation of a three-dimensional network structure. The functional properties of caseins were significantly enhanced following glycosylation, with notable improvements in thermal stability and three-phase contact angle. Furthermore, the emulsification activity (EAI), emulsification stability (ESI) and apparent viscosity of covalent complex-stabilized emulsions were markedly improved. Notably, the EAI and ESI of the CS-KGM_MRPs group reached a maximum of 20.10 m²/g and 64.96 min, respectively. This study provided a theoretical basis for further research on casein-stabilized emulsions and expanded their applications in the food industry.