Our Two Senses of Smell

It’s lunchtime. You heat up those Chinese takeout leftovers in the microwave and the aroma makes you hungry. Then you take a bite—delicious.

Clearly, you process the smell from the microwave through your nose. But did you know that processing flavor also comes from your sense of smell?

In his new book Neurogastronomy: How the Brain Creates Flavor and Why It Matters, Dana Alliance Member Gordon M. Shepherd explains that we actually have two senses of smell: orthonasal and retronasal.

Orthonasal smell is what happens when we sniff—we breathe in through our noses to sense environmental odors, like the smell from the microwave.

Retronasal smell, on the other hand, is where flavor comes from. Try holding your nose while eating some of those leftovers—you won’t taste much. Breathing out while eating is the doorway to flavor. While we are born recognizing sweet, sour, salty, bitter, and  umami—which are tastes, not flavors, writes Shephard,  “retronasal smells are learned and thus open to individual differences. They account, therefore, for the vast variety of cuisines in the world.”

Bon appetit!

--Johanna Goldberg