Tasting Acids and Bases
The solutions in "Using Your Tongue" are acids or
bases. The vinegar and citrus solutions are acids, which have
a sour taste. The baking soda and unsweetened chocolate solutions
are bases, which have a bitter taste.
For many years it was believed that taste buds were adapted for particular taste. But later research has shown that taste buds contains 50 to 100 receptors for each taste, so sensitivity to a particular taste is not limited to only certain regions of the tongue.
Using Your Tongue