Before we even had a chance to figure out the sound of one hand clapping, the Japanese have given us a riddle of a different sort:
kokumi. Think of it like this: when is a flavor not a flavor? When it's kokumi! Confused? Apparently, so are a lot of food journalists who got all excited when Japanese researchers announced that they had discovered a whole new taste to add to the five we already know -- except, wait a minute, kokumi has no taste. Huh?
Sweet, sour, salty, bitter-those are pretty self-explanatory. Then there's
umami, also identified by the Japanese and now commonly accepted as the "fifth" basic taste. It roughly translates to "savory." (According to the
Food & Think blog at Smithsonian.com, it more accurately translates to "yummy," but that's not very helpful for explaining things.)
Now here comes kokumi. Unlike sugar, which of course tastes sweet, or salt, which (duh) tastes salty, the compounds in food that relate to kokumi don't have an identifiable taste in and of themselves. Instead, they appear to heighten the sensation of other flavors by activating calcium receptors on the tongue, making salty foods taste even saltier, for example, or savory foods taste more savory.