This is scientific American's 60 second science. I'm Christopher Intalyata. Got a minute?

Ever lose your ability to taste during a cold because your nose is stuffed up?

That's because the nose is intimately involved with taste.

And when you chew, volatile flavor compounds from the food get lofted up toward the back of the mouth.

And when you exhale, you carry some of those flavor compounds up into your nasal cavity,

where they hit olfactory receptors.

As children, we basically learn the first lesson in the table manners,

you know, just to keep the mouse close while chewing and you also want to breathe smoothly.

It's Rayne, a mechanical engineer at Penn State.

I think it's not only because it's courteous, but also because it actually can smell the food much better if you can breathe

smoothly.

The backdoor by which smell contributes to taste is called retro-nasal olfaction, and it turns

out our airways are exquisitely tuned to enhance that effect.

Nee and his colleagues 3D printed a model of a woman's airway using a CT scan as a template.

To track airflow, they laced water with fluorescent particles

and pumped it through the apparatus filming the results. They found that when you

breathe in, that inward airflow actually forms a curtain at the back of your mouth, blocking food

particles from getting into the lungs, which is a good thing. And when you exhale,

air swirls through that cavity in the back of the mouth,

sweeping up those volatile particles, and delivering them right to the nasal cavity,

where you can smell them.

The results appear in the proceedings of the National Academy of Sciences.

...