Exploring the metabolic dynamics, storage stability, and functional potential of Lacticaseibacillus rhamnosus Probio-M9 fermented milk

Lacticaseibacillus rhamnosus Probio-M9 (Probio-M9), a probiotic strain sourced from healthy breast milk, is recognized for its resilience to gastric and bile acids, along with its potential health benefits for infants. Its unique origin may influence its metabolic properties and effectiveness, garnering increasing interest within the scientific community in recent years. However, research on its efficacy as a starter culture for milk fermentation and the associated metabolic shifts remains limited. This study aimed to track the dynamic metabolomic changes of Probio-M9 during the fermentation process. We utilized Probio-M9 as the sole inoculant for milk fermentation, collecting samples at 1.5 to 3-h intervals to monitor the fermentation progression. Moreover, the metabolomics changes of the fermented milk were investigated after a 28-d storage period to evaluate post-storage stability. Metabolite profiles were generated using ultra-high performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS