If you give a kid a jelly bean, and tell her to plug her nose, she will probably tell you it tastes sweet.
But when you tell her to unplug her nose, she’ll be able to tell you it was actually a lemon-flavored jelly bean.
It’s been pretty common knowledge that most of taste comes from what you smell, but scientists are now starting to characterise this phenomenon in much more detail — and figure out how the brain plays a role.
He told Tech Insider about this simple jelly bean experiment, which he also outlined in his book, and explained why it works.
While inhaling can send us aromas, it isn’t what’s responsible for flavour.
“It’s breathing out that determines what the actual flavour is going to be of the foods,” he said. “Food moves through our mouths giving off volatiles that then are picked up by the airway and taken by exhaling air to our noses … What we call taste of food is mostly smell, and it’s done by breathing out.”
It sounds counterintuitive, but it’s exhaling that pushes molecules of food from the back of your mouth up to your nasal passage. This is called your “retronasal” sense of smell, and it plays a key part in giving us a full experience of a food’s flavour.
“The retronasal route is the main source of the smells we perceive from foods and liquids within our mouths,” Shepherd wrote in a paper published in PLOS Biology. “These are the smells that primarily determine the hedonic (i.e., pleasurable or aversive) qualities of foods, and that, combined with taste and somatosensation, form the complex sensation of flavour.”
When you inhale, you can smell food, of course. But it’s exhaling that actually helps you taste it.
Shepherd and some of his colleagues created a model to demonstrate how this works in a study published last year. (The study was based on a model built around one person, so it’s possible this system works a little differently in different people, as NPR noted.)
The idea that your ability to sense flavour leans heavily on your ability to exhale explains why you can’t taste as much when your nose is stuffed, like when you have a cold or when you’re aboard the International Space Station.
So the next time you eat something, go slow. Try to feel the sensation of taste not just in your mouth, but in your nose as well.
Breathe in, as the mantra goes, but especially remember to breathe out.