Abstract:In order to enrich the beneficial bacteria species and active substances in the fermentation products of yam，using yam as raw material，Streptococcus thermophilus and Lactobacillus plantarum were selected as compound fermentation strains.On the basis of single-factor experiments，the fermentation conditions of compound Lactobacillus fermentation in yam were optimized by orthogonal test.The results showed that the optimum fermentation conditions were obtained as follows：fermentation temperature 40℃，fermentation time 16 h，strain inoculum 5%，sucrose addition 3% and strain inoculation volume ratio 1∶1.Under the optimal fermentation conditions，the viable count was（8.62±0.02）lg（CFU/mL），and the total polysaccharide content in the fermentation process decreased with time.