Peptide profiling to predict bitterness in fermented milk from different bacterial cultures and relationship with human bitter taste receptor activation

Microbial fermentation is frequently used in the food industry to enhance organoleptic experience. In fermented milk and yogurt, peptides released from milk protein upon fermentation can contribute to a bitter taste in the final dairy product, depending on the lactic acid bacterial cultures used. This work used five lactic acid bacteria (LAB) strains: Lactobacillus helveticus (LH), Leuconostoc mesenteroides (CL3), Leuconostoc pseudomesenteroides (CL3ST), Lactococcus lactis (BL1), Streptococcus thermophilus (ST), to investigate the relationship between peptides produced from fermented milks and their ability to activate human bitter taste receptors (TAS2R) in vitro. Label-free peptidomics was performed and relative abundances of bitter peptides compared, based on predicted in silico sequence analysis (in-house database search and Q-values). Milk fermented by LH had the highest number of bitter peptides and was also more efficacious at activating the bitter receptor in vitro, while milk fermented by ST had the least. This work demonstrates that the potential bitter taste of fermented milk can be estimated from the profile of the peptides generated by the lactic acid bacteria fermentation. This approach may be applied to evaluating bitter taste in development of novel dairy products.