Saccharides are also organic, but not like sugar in structure. Bitter substances often are AB, H, in a different pattern than sugars. These all contain nitrogen. Large negative ions tend to taste bitter rather than salty. We often add a little salt to desserts.
Ions penetrate the microvillus.
React directly to any electrically charged molecules by altering electrical properties of the membrane 17. Also they vary across the tongue. Sour is most detectable on BACK AND SIDE of tongue. Caffeine involves a LOT of variability. Weber fractions in taste vary from .1 to 1.00, showing LACK of sensitivity.