Development and sensory evaluation of soy milk based yoghurt

Yoghurts were prepared by fermentation of soy milk using a mixed starter culture containing Lactobacillus bulgaricus and Streptococcus thermophilus. Soy milk at 9 degrees Brix was homogenised under pressure (17 MPa) and fermented with and without addition of sucrose (2.0 and 2.5 g per 100 g) for 4, 5, 6 and 7 hours. The yoghurts were evaluated in terms of sensory quality, pH, titrable acidity, phytic acid and oligosaccharides: A yoghurt with the best sensory quality was obtained using the homogenised soy milk with 2% sucrose addition and fermented for 6 h. Lactobacillus bulgaricus and Streptococcus thermophilus did not produce phytases and alpha-galactosidases at the experimental conditions, consequently, phytic acid and galactosides were not affected by the process.