Optimization of Two Kinds of Probiotics Mixed Fermentation on Whey Medium

The Lactobacillus acidophilus and Bifidobacterium mixed fermentation of whey medium was optimized by the response surface method according to the nutritional needs and growth characteristics of the strains.Three significant factors of Lactobacillus acidophilus and Bifidobacterium mixed fermentation cultivation were soybean protein isolated,tomato juice and carrot juice,which were selected via Plackett-Burman design of SAS soft.The factors level was determined by the steepest ascent experiment.Then the optimal mixed fermentation of whey medium,which was as follows: Whey powder 4 %,Soybean protein isolated 1.4%,Tomato juice 10 %,Carrot juice 13 %,Cysteine hemifumarate 0.5 %,oligo-isomaltose 0.04 %,K2HPO4 0.3 %,was obtained rest on the analysis of regression model.Using the optimal medium to culture Lactobacillus acidophilus and Bifidobacterium,the viable cell numbers was 9.8×109 cfu/ml.