Optimizing the formula for Puerarin radix fermented soymilk by response surface methodology

The paper took soybean, Puerarin radix and sugar as the main raw material, which identified the effect of sugar, Puerarin radix juice, inoculation and fermenting time on sensory score and content of lactic acid of Puerarin radix fermented soymilk through the single factor experiments. Based on these experiments, according to the Box-Behnken design method, it introduced response surface methodology to establish the nonlinear second order polynomial regress equation and numerical model for the optimized recipe of Puerarin radix fermented soymilk by sensory scores, and confirmed the amount of sugar, amount of Puerarin radix juice, amount of inoculation.The result showed that the theoretical optimum formulas were as follows:7.86% of sugar, 18.0% of Puerarin radix juice and 0.35% of inoculation.The sensory score of optimized verification test up to90.3 ( n = 3) , which was close to the predicted value ( 89.62) , deviation was 0.76%. The result showed that the texture, water holding, lactic acid bacteria, protein, and content of puerarin isoflavone of the fermented soymilk was better than commercial products and it has value of commercial promotion.