Sodium, but not potassium, blocks bitterness in simple model chicken broths

Potassium chloride (KCl) has proven useful as a salty taste replacer to help reduce dietary sodium. But unlike sodium, which in simple aqueous solutions blocks the perception of bitterness of selected compounds, KCl does not blocker bitterness. We tested the ability of potassium to block bitterness in a more complex translational system by presenting model chicken broths to healthy adults. Broths were presented in three added salt conditions: (1) no added salt, (2) salted with sodium chloride (NaCl), or (3) salted with KCl. To create a model bitter off-taste, four concentrations of l-tryptophan (l-tryp, present in chicken meat) were added to each broth. In Experiment 1, the base broth consisted of chicken flavor only. In Experiment 2, the base broth was more complex, containing savory (umami) ingredients. In both experiments, subjects rated broths with either added NaCl or KCl as saltier than unsalted broths. Only NaCl, however, suppressed bitterness (by about 30%, across a wide range of l-tryp concentrations). Accordingly, when complex foods have sodium reduced and potassium increased to balance salty taste, the bitterness reducing properties of sodium will need to be replaced independently, since potassium does not share this effect.