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. PRACTICAL APPLICATIONS: The present paper describes the optimized process of soy yoghurt development. Single probiotic culture was used to develop probiotic soy yoghurt. As single culture is used, the product of consistent quality could be obtained. Response surface methodology has been utilized for process optimization; the obtained model could be used to find out the optimum parameters for any factor combination. The information provided could be useful for large‐scale development of probiotic soy yoghurt.