EFFECT OF SOME SELECTED PREBIOTICS ON RHEOLOGICAL PROPERTIES OF SET YOGHURT

The objective of this paper was to determine the effect of the additions of P95 fructooligosaccharide and GR and HPX inulins on the theological properties and the syneresis extent of yoghurt produced using a thermostat method. The hardness, apparent viscosity, and syneresis extent of set yoghurts were determined. In order to determine the effect of fiructooligosaccharides on the course of fermentation process, this process was monitored using an oscillatory rheometer. In the case of control sample of yoghurt, the curd began to form ca. 90 minutes after the process started whereas, in the case of all other yoghurts, the curd started to form after about 105 min. The control sample of yoghurt had the lowest hardness value of 0.23 N. The yoghurt with the HPX inulin added in the amount of 3 % had the highest hardness: 0.28 N. As for the yoghurts with P95 inulin added, a slightly higher value of hardness was reported compared to the control sample. The lowest amount of whey excreted was found in the case of yoghurt with the added 3 % amount of P95. Generally, for all of the yoghurts examined, the syneresis extent decreased with the increasing amounts of fructooligosaccharides added. The application of fructooligosaccharides allows for manufacturing yoghurts characterized by proper theological and pro-health properties.