Effect of cross-linked acetylated starch content on the structure and stability of set yoghurt

Abstract In this research, the effect of cross-linked acetylated starch on the set yoghurt system was studied by investigating the flowability, viscoelasticity, zeta potential, conductivity and microstructure of the set yogurt system. The results indicated that the stability, elastic modulus ( G ′) and viscous modulus ( G ″) of the set yogurt system increased as the concentrations of cross-linked acetylated starch increased. The set yogurt system, which added the cross-linked acetylated starch, exhibited shear-thinning behavior and belonged to yield pseudoplastic fluid. The SEM micrographs demonstrated that the microstructures of set yoghurt were mainly composed by the network of casein. By adding cross-linked acetylated starch, the network of casein was strengthened, and both conductivity of the yoghurt system and particle size of casein micelles due to absorption of modified starch revealed the aggrandizement trend. It can be deduced that the starch adsorbs onto the surface of the casein micelle and this phenomenon prevents flocculation of the casein micelles owing to electrostatic adhesion, steric stabilization and osmotic effect.