Super sense combines smell with taste

Our senses of smell and taste are anatomically different senses, with smell detection happening in the nose and taste happening on the tongue through taste buds. Yet they work together forming a super sense, something foodies and food makers know well. But how?

Turns out we humans have something called a “chemosensory system” that helps us locate and identify food and other important chemicals while avoiding harmful substances. This system includes both the sense of smell and taste, according to the National Institute of Health’s website on smell.*

We distinguish the difference between oranges and chocolate through sensory cells that line the channel from the nose to the roof of the throat.

Nose-Throat Channel

Two pathways usher smells to our olfactory neurons. The first is through the nose as described last week. The second is through the sensory cells that line the channel from the roof of the throat up to the nose. When we chew food, aromas are released into this channel that get picked up by the sensors that line it.** These sensory cells detect subtle chemical differences, for example, between oranges and chocolate (as opposed to more stark chemical differences, such as between sugar and salt).

If the nose-throat channel becomes blocked, such as when our noses are stuffed up from a cold or flu, odors cannot reach the sensory cells and much of our ability to enjoy a food’s flavor is lost. In this way, our senses of smell and taste work closely together… — National Institutes of Health**

Manipulating Flavors

With smell and taste linked through the nose-throat channel, it’s possible to manipulate flavors by targeting the sensory cells in the channel; it’s something chefs do for a living. Harold McGee, food writer and columnist for The New York Times Curious Cook, spoke about taste in a recent interview with Terry Gross, host of the NPR radio show Fresh Air. In the interview McGee described easy ways to enhance the flavor of food. He noted specifically that the addition of salt or acid to a dish just before serving can greatly improve the amount of flavor. But how?

Both salt and acids, such as lemon juice or vinegar, change the chemistry of food. Specifically, adding salt to a dish just before serving “makes the food want to release more aromas, which makes it taste better,” according to McGee. By waiting to salt the dish just before serving, rather than during cooking, the food aromas are released into the nose-throat channel instead of the kitchen.

This morning I decide to test McGee’s suggestion and sprinkle salt on my toast. I take a bite and right away get a flash in my brain that registers salt. I’m off to a good, if not basic, start. Then I chew the crunchy bread so that it mixes with the salt and let it sit on my tongue until it all gets soft. A minute or so into it, the bread turns sweet like cake. It’s a revelation!

Salt and acid (or sour) are two of the five basic tastes. The other are sweet, bitter and umami (or savory/fermented). Altogether, an individual human tongue contains about 10,000 taste buds.

* Source: NIDCD.nih.gov
** See Eater’s Digest, an interesting blog about chewing

ABOUT THIS COLUMN: This weekly feature, the Science of Smell, appears on Fridays and endeavors to answer basic questions about this ancestral sense.


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