Rheological and Sensory Evaluation of Yoghurts Containing Probiotic Cultures

In this study, the possibility of including probiotic starter cultures for making yoghurt was investigated. Set yoghurts were made using three bio-cultures, all containing Bifidobacterium spp.. The effects of these starter cultures and total solids (i.e. addition of 0, 1 and 2% skim milk powder) on the rheological and sensory characteristics of the bioyoghurts were compared with a standard starter culture (CH1) on the day of production (Day 0) and after 7 and 14 days storage at 4oC. The rheological properties were evaluated using a Universal Texture Analyser and sensory analyses were carried out using a five point hedonic scale. The results of texture studies showed that the type of starter culture had a significant effect on the rheological parameters including hardness, springiness, cohesiveness, adhesiveness, chewiness and gumminess (P<0.05). It was also concluded that addition of skim milk powder (at the levels tested) did not change the hardness and springiness significantly, while adhesiveness, cohesiveness, gumminess and chewiness were statistically different at P<0.05. The results of sensory analysis indicated that the overall acceptance of bio-yoghurts was higher compared with the control. The higher sensory and textural scores of bio-yoghurts as well as their potential therapeutic effects may well be encouraging for the Iranian dairy industry.