OPTIMIZATION OF FERMENTATION CONDITIONS FOR PROBIOTIC SOY YOGHURT USING RESPONSE SURFACE METHODOLOGY.

Response surface methodology was adopted in order to optimize the fermentation process conditions for the development of probiotic soy yoghurt utilizing single probiotic culture i.e., Streptococcus faecalis, without using any additives. The experiments were designed following central composite rotatable design with three independent variables i.e., inoculation concentration (1-3% v/v), incubation temperature (37-43C) and incubation time (12-15 h). Lack-of-fit tests were insignificant and determination coefficients were high ranging from 79.59 to 95.11%, except in the case of syneresis (53.54%). The results revealed that inoculum concentration, incubation temperature and incubation time influence the physicochemical properties of soy yoghurt. The optimized conditions were as follows: inoculum concentration, 1.78%; incubation temperature, 40.53C (41C); and incubation time, 16 h, for the preparation of probiotic soy yoghurt with 80.7% desirability. [ABSTRACT FROM AUTHOR]