Bitter peptides formed during in-vitro gastric digestion induce mechanisms of gastric acid secretion and release satiating serotonin via bitter taste receptors TAS2R4 and TAS2R43 in human parietal cells in culture

A key barrier in transitioning to plant-based, more satiating diets, is the bitter taste of plant proteins. We hypothesize that both, a more bitter tasting (MBT) and a less bitter tasting (LBT) pea protein hydrolysate (PPH) can be digested in the stomach into bitter tasting peptides that stimulate proton secretion (PS) and serotonin release, as two of the key gastric satiety signals, via the functional involvement of bitter taste receptors (TAS2Rs). Using a sensory-guided LC-MS approach, we identified six bitter peptides that were released from LBT-PPH and MBT-PPH during gastric digestion in vitro. TAS2R4 and TAS2R43 involvement in PS and serotonin release was confirmed via CRISPR-Cas9 knockout experiments. Our hypothesis was proven with all six peptides equally stimulating PS in immortalized human gastric HGT-1 cells, and LBT-PPH-derived peptides eliciting a higher serotonin release in HGT-1 cells than MBT-PPH peptides, indicating a satiating potential of less bitter tasting protein hydrolysates.