Metabolic footprinting revealed key biochemical changes in a brown fermented milk product using Streptococcus thermophilus

Abstract

Ultra-performance liquid chromatography coupled with a quadrupole-time-of-flight mass spectrometry^{Elevated Energy} was used to investigate changes in the metabolite profile of brown milk and fermented brown milk produced using Streptococcus thermophilus S10. Samples were analyzed in both positive and negative electron ionization modes. Data were analyzed by multivariate statistical methods for biomarker metabolites that were differentially abundant in brown milk and fermented brown milk. We identified 43 differentially abundant metabolites based on mass spectrophotometry fragmentation patterns. These metabolites included peptides, AA, fatty acids and related metabolites, carbohydrate metabolites, vitamins, and nucleosides. Some of these metabolites are known to alter the sensorial quality of fermented dairy products. Thus, it is likely that some of the currently identified differentially abundant metabolites also contribute to the unique flavor, taste, and aroma of fermented brown milk. The bitterness and astringency of fermented brown milk are likely to be due to some of these peptides, whereas the sweetness and sourness could be a result of changes in carbohydrate levels. No previous study has analyzed metabolomics changes during fermentation of brown milk. Thus, our data are a valuable reference for future development and improvement of fermented brown milk products.

Keywords: Streptococcus thermophilus; fermented brown milk; metabolite; ultra-performance liquid chromatography coupled with a quadrupole-time-of-flight mass spectrometry with elevated energy.