Different growth behaviors and metabolomic profiles in yogurts induced by multistrain probiotics of Lactobacillus casei Zhang and Bifidobacterium lactis V9 under different fermentation temperatures

Abstract
The growth behaviors and metabolomic profiles in yogurts induced by multistrain probiotics of Lactobacil-lus casei Zhang (LCZ) and Bifidobacterium lactis V9 (V9) at the fermentation termination and 10 d of stor-age at 4 degrees C under different fermentation temperatures (37 degrees C and 42 degrees C) were compared using metabolomics based on liquid chromatography-mass spectrom-etry and gas chromatography-mass spectrometry. The growths of LCZ and V9 were affected by fermentation temperatures; the viable cell density of LCZ was higher at 37 degrees C than that at 42 degrees C; however, V9 was higher at 42 degrees C. Multistrain probiotics had higher contribution to the changes in volatile and nonvolatile metabolomic profiles at 42 degrees C than those at 37 degrees C. At fermentation termination, there were 2 common enriched pathways increased by multistrain probiotics at 37 degrees C and 42 degrees C, which were biosynthesis of peptides and amino-and nucleotide-sugar metabolism. At 10 d of storage, 4 common increased enriched pathways were alanine, aspartate and glutamate metabolism; tyrosine metabo-lism; valine, leucine, and isoleucine degradation; and valine, leucine, and isoleucine biosynthesis. This work provided a detailed insight into different effects of dif-ferent multistrain probiotics of LCZ and V9 fermenta-tion temperatures on the growth behaviors and volatile and nonvolatile metabolomic profiles of yogurts.