Abstract:The fermentation conditions of Polygonatum sibiricum-hawthorn compound enzyme by lactic acid bacteria were optimized，and the changes in compound enzyme quality before and after fermentation were analyzed.As revealed by the exploration of the growth performance and acid resistance of five lactic acid bacteria，Lactobacillus plantarum AS 1.2437 and Lactobacillus casei CICC 21019 with good fermentation performance were selected as fermentation strains.The effects of strain volume ratio，P.sibiricum and hawthorn mass ratio，inoculation amount，fermentation temperature，and fermentation time on the quality of compound enzyme were investigated with the content of total flavonoids and sensory score as comprehensive evaluation indexes.On the basis of single factor test，the fermentation process was optimized by response surface test，and the changes in sensory quality，basic physical and chemical indexes，and functional components before and after fermentation were analyzed.The results showed that the optimal fermentation parameters of the compound enzyme were as follows：the strain volume ratio of 2 ∶1，the P.sibiricum to hawthorn mass ratio of 5 ∶1，the inoculation amount of 4%，the fermentation temperature of 34℃，and the fermentation time of 52 h.Compared with the results in the control group without fermentation，the sensory score，the content of total acid and total flavonoids，and superoxide dismutase（SOD）activity of the compound enzyme prepared under the optimized conditions increased（P＜0.05），and the pH value and the content of soluble solids and reducing sugar decreased（P＜0.05）.The viable count of lactic acid bacteria reached 3.42×109CFU/mL.