The mechanisms underlying these varied sensory effects of salt in foods are not well understood. In particular, how salt increases the perceived body or thickness of liquids such as soups is a mystery. It is conceivable that in addition to interacting with salt taste receptor(s), salt could also activate somatosensory (touch) neural systems.
One understood mechanism by which sodium-containing compounds may improve overall flavor is by the suppression of bitter tastes. Various sodium-containing ingredients have been known to reduce the bitterness of certain compounds found in foods, including quinine hydrochloride, caffeine, magnesium sulfate, and potassium chloride (Breslin and Beauchamp, 1995). Further, the suppression of bitter compounds may enhance the taste attributes of other food components. For example, the addition of sodium acetate (which is only mildly salty itself) to mixtures of sugar and the bitter compound urea enhanced the perceived sweetness of this mixture as a consequence of sodium suppressing bitterness and thereby releasing sweetness, as illustrated in Figure 3-3. No change in sweetness was found when