Optimization of Fermentation Process and Cold Storage Stability of Probiotic Yam Beverage

In this study,yam powder was used as raw material,probiotics Lactobacillus plantarum P-8 and Bifidobacterium lactis V9 were used as starter,and the fermentation process was optimized to obtain a probiotic yam beverage with yam nutritional value and probiotic probiotic characteristics. The effects of fermentation time,inoculum size and fermentation temperature on the number of viable bacteria,titrated acidity and pH in the beverage were studied by single factor experiment. Based on this,the optimal fermentation process parameters of fermented probiotic yam beverage were obtained by response surface analysis as follows:inoculum size of 2×10⁶ CFU/mL,fermentation time of 19.1 h and fermentation temperature of 37℃.Under these conditions,the viable count of the beverage was 4.3×10⁸ CFU/mL and the titrated acidity was 105.3°T. The number of viable bacteria in the beverage remained stable at 10⁸ CFU/mL during storage at 4℃ for 28 days,and the beverage had good tissue state,stable flavor and mouthfeel.