Abstract: The tolerance of Lactobacillus plantarum LPb1 in stimulated human digestive environment such as artificial gastric and intestinal fluid was tested. Lactobacillus plantarum LPb1 was first trrsyrf with artificial gastric juice for 3 h, then with artificial intestinal juice for another 3 h at 37 ℃, the survival rate of Lactobacillus plantarum LPb1 cells was 88.6%. LPb1 mixed with a strain of Streptococcus thermophilus was inoculated into skim milk to produce yogurt. The results showed the combination starter produced acid well and the final products had good water retention property, meanwhile the yogurt was weak in post-acidifying activity at the storage temperature (4 ℃). Taking sensory evaluation as indicators, the optimum fermentation conditions were inoculums size of 4.45% of mixed culture, fermentation temperature 40.40 ℃, and fermentation time 8.53 h.

Key words: Lactobacillus plantarum LPb1, tolerance, response surface analysis (RSA)