The overall flavor of a fruit or vegetable is a composite of several distinct sensations. From the taste buds on our tongues, we register salts, sweet sugars, sour acids, savory amino acids, and bitter alkaloids. From the cells in our mouth sensitive to touch, we notice the presence of astringent, puckery tannins. A variety of cells in and near the mouth are irritated by the pungent compounds in peppers, mustard, and members of the onion family. Finally, the olfactory receptors in our nasal passages can detect many hundreds of volatile molecules that are small and chemically repelled by water, and therefore fly out of the food and into the air in our mouth. The sensations from our mouth give us an idea of a food’s basic composition and qualities, while our sense of smell allows us to make much finer discriminations.