Abstract: This work studied the effects of three different prebiotics inulin, fructooligosaccharide and galactooligosaccharide on the gelation process and microstructure of yogurt. Yogurt without prebiotic was used as a blank control. An optical microrheometer, a Turbiscan stability analyzer and a scanning electron microscope were used to detect the rheological parameters, stability and microstructure of the yogurts with prebiotics during fermentation and storage, respectively. The results showed that in contrast to the other prebiotics, inulin incorporation to yogurt formed a more uniform and loose microstructure. The solid-liquid balance of the yogurt containing fructooligosaccharides was less than 0.5, indicating that fructooligosaccharides were more conducive to enhancing the solid nature of yogurt, while the yogurt containing galactooligosaccharide had better microscopic stability. Therefore, the three prebiotics had different effects on the gelation process and microstructure of yogurt. Still, further studies are needed to ascertain the synergistic effect of these prebiotics on the overall quality of yogurt.

Key words: yogurt, prebiotics, gelation process, microstructure