Streptococcus thermophilus CCFM1095 in combination with Lactobacillus helveticus CCFM1263 significantly improves fermentation efficiency， but the mechanism of interaction has not been cleared. Therefore， this paper evaluates the fermentation characteristics of the complex strains and the metabolomic profiles of the fermented milks， and analyses the effects of key metabolites on fermentation characteristics. Metabolomics analyses showed that compounding significantly promoted the enrichment of pathways such as alanine， aspartate and glutamate metabolic pathways， lysine degradation pathway， TCA cycle， pyruvate metabolism and nicotinic acid and nicotinamide metabolic pathways， and increased the utilisation of citrate and nicotinamide by the strains Production of L-glutamate， fenugreek acid， α-ketoglutarate， and 4-trimethylaminobutyric acid lipids， which significantly promoted the growth of both strains. The fermentation characteristics of the complex fermented milk were significantly improved. The viable bacterial count of the strains could reach 108 CFU/mL. This study provides theoretical basis for further analysis of the interaction mechanism between Streptococcus thermophilus and Lactobacillus helveticus.

Streptococcus thermophilus  /  Lactobacillus helveticus  /  fermented milk  /  sensory evaluation  /  volatile compounds  /  non-volatile compounds