effect of thickening agents on physicochemical, sensory and microbial properties of set fruit yoghurt

fruit yoghurt is frequently made with fermented milk products; however, the use of fruit and its products may cause changes in the viscoelastic properties, syneresis and sensory properties of fruit yoghurt. one approach to improve these properties in fruit yoghurt is the use of thickening agents. this study investigated the effect of carboxymethyl cellulose and guar thickening agents on the properties of set fruit yogurt. syneresis decreased and water holding capacity increased as carboxymethyl cellulose and guar increased up to 0.2% and 0.06%, respectively. the type and content of hydrocolloids at all concentrations had no significant effect (p< 0.05) on mold and yeast growth. increasing the concentration of these two thickening agents up to critical levels produced no negative effects on sensorial properties such as color, coarseness, cohesiveness and adhesiveness. different mechanisms effected the formation of yogurt structure. no synergistic effect was observed on improvement of the gelled structure and physicochemical properties of the yoghurt.