In this study, soy yoghurt was produced at three stages according to Iranian preferences. Soy-yogurt was incubated with 3% (V/V) bacteria culture which consisted of a 1:1 number ratio of S. thermophilus and L. bulgaricus.
In the first stage, the effect of soy variety (Pershing & Williams), extraction ratio (1:6, 1:8 & 1:10; dry beans: Water) concentration whey (0, 10, 20, 30, 40% based on dry weight), and incubation temperature (25°C & 41°C) on the quantity (total solids, pH and acidity) and quality (taste, consistency, appearance, color and odour) characteristics of soy yogurt were evaluated.
In the second stage, the best sample from first stage was formulated in four different ways (simple, with 3% sugar, with 3% sugar plus 0.01% vanilla, and with 3% sugar plus 5% apple juice concentrated. Samples were then compared with each and with cow’s yoghurt.
In the third stage, the consumption attributes determined.
The results were shown that the best quality of soy yogurt will be achieved if perishing variety, the extraction ratio of 1:8, 20% whey, and the incubation temperature 25°C are applied. On the other hand, simple yoghurt was selected as the best formulation with the 84% of the consumer acceptability and with mean score 1.31. Furthermore there were not significant differences between simple soy yoghurt cow’s yoghurt at p<0.05 level.