EFFECT OF CERTAIN DIETARY FIBERS ON THE PROPERTIES OF FUNCTIONAL YOGHURT.

Two types of dietary fiber (maltodextrin and konjac) were used to evaluate the effect of dietary fibers on the properties of plain yoghurt fermented with the traditional yoghurt starter(streptococcus thermophillus and lactobacillus delbruki susps. bulgaricus. All treatments were evaluated for chemical, rheological, microbial as well as the sensory properties, and compared with the control plain yoghurt. Dietary fibers were added at (0.5 , 2.0 %) for maltodextrin and (0.2 , 0.4 %) for konjac fiber (w/w). Control and other treatments were monitored during refrigeration storage (4°C) for 15 days. Results showed that all treatments were characterized with increase in total solid, soluble nitrogen, non protein nitrogen, total nitrogen and total volatile fatty acid, when compared with the control. Titratable acidity of various yoghurt treatments gradually increased during storage period. The dietary fibers had pronounced effect on the curd tension, whereas they decreased the syneresis of yoghurt. Moreover, the addition of dietary fiber improved the viability of lactic acid bacteria which varied in their decreasing rate when all treatment compared with the control. The body texture and flavor of the yoghurt were enhanced when fortified with dietary fiber.