Why Does Food Taste Different When Your Nose Is Blocked?

A cold can make your favorite food taste like a cheap imitation of itself.

You bite into something you normally enjoy and immediately notice something is missing. You can tell it's sweet, salty, sour or bitter, but the actual flavor seems strangely faint.

Strawberry doesn't really taste like strawberry.

Chicken doesn't taste quite like chicken.

Coffee suddenly seems mostly bitter.

Your tongue hasn't stopped working. Your nose has become much less useful, and that turns out to matter a lot more than most people realize.

The easiest way to see why is with a very simple experiment.

Try eating a jellybean with your nose blocked

You'll need a few jellybeans with different flavors, a glass of water, and someone who can hand you the jellybeans without telling you which ones you're getting.

Close your eyes.

Pinch your nose shut.

Put one jellybean in your mouth and chew it.

Don't release your nose yet.

Pay attention to what you can actually identify.

You should still notice sweetness. You may notice sourness too, depending on the candy. You'll feel the texture. You might even get some clues from the way the candy behaves as you chew.

But identifying the exact flavor can suddenly become much harder.

Now release your nose while you're still chewing.

The flavor can seem to appear almost immediately.

That's the strange part.

Nothing about the jellybean changed.

The taste receptors in your mouth were already working.

What changed was the smell information reaching your brain.

This simple nose-pinching experiment has been used as a demonstration of the relationship between taste and smell, including by Scientific American.

And it's useful because it lets you separate two things that we normally experience as one.

Taste.

Flavor.

They're not the same.

Your tongue doesn't actually know what a strawberry tastes like

Your taste buds detect basic tastes.

Sweet.

Salty.

Sour.

Bitter.

Umami.

That's their job.

But your tongue isn't detecting all the individual aroma compounds that make a strawberry smell like a strawberry.

Your nose is involved in that.

When you chew food, volatile compounds are released. Some of them travel from the back of your mouth, through the throat and into the nasal cavity.

Your smell receptors detect them there.

Scientists call this retronasal olfaction.

It's still smell, but you're experiencing it while eating rather than sniffing food through the front of your nose.

Your brain combines that information with the basic tastes coming from your tongue, along with texture, temperature and other sensations.

That's what gives you the much richer experience you call flavor.

So when you block your nose, you're not turning off taste.

You're removing a major source of information that your brain normally uses to identify what you're eating.

A better version of the experiment

The jellybean trick is fun, but you can make it much more revealing.

Use three or four flavors that have similar basic tastes but different aromas.

Have someone else choose the order.

Keep your eyes closed.

Rinse your mouth with water between samples.

Then test each food twice.

First with your nose open.

Then with your nose blocked.

Write down your guess before you release your nose.

That's important.

Otherwise, it's very easy to convince yourself afterward that you knew what the food was.

You can even score the results.

For example:

Condition	Correct flavor guesses
Nose open	4/4
Nose blocked	1/4
Nose released while chewing	4/4

The numbers above are an example of how to record the experiment, not results from a test we personally performed.

The interesting measurement isn't whether someone gets every answer right.

It's the difference between the conditions.

If you can easily identify the flavors with your nose open but struggle when it's blocked, you've just demonstrated how much information smell contributes to flavor.

Researchers have run more controlled versions of this idea with real foods. In one study involving vegetables, participants tasted foods with their noses open and closed and rated different sensory qualities. The researchers found that closing the nose affected how much participants liked the vegetables, showing that retronasal odor was contributing to the eating experience.

Why can you still taste the sugar?

Because your taste buds are still doing their job.

Suppose you put a sweet jellybean in your mouth while holding your nose.

You'll probably know that it's sweet.

That's taste.

But "sweet" doesn't tell you whether the jellybean is strawberry, cherry, raspberry or another fruit flavor.

Those foods can share basic taste sensations while having very different aromas.

Your nose supplies much of the information that helps distinguish them.

That's why the experiment can feel so weird.

You're clearly tasting something.

You just can't easily figure out what that something is.

Then you let go of your nose

This is the part worth paying attention to.

Keep the food in your mouth and release your nose.

You haven't taken another bite.

You haven't added anything.

The food hasn't changed temperature.

Yet the flavor can suddenly become much clearer.

That's because aroma compounds from the food can now reach the olfactory receptors through the nasal passage.

The route is from the mouth toward the back of the nose rather than simply from the outside world through your nostrils.

That's retronasal smell.

And it's one reason flavor perception is so heavily tied to the sense of smell.

Research on retronasal olfaction describes smell as a major part of flavor perception, particularly during eating.

So why does food become bland when you have a cold?

Now the experience makes a lot more sense.

When you're congested, air and aroma compounds may have a harder time reaching the smell receptors in your nasal cavity.

Your tongue can still detect sweetness.

It can still detect saltiness.

It can still detect sourness.

But you've lost access to much of the aroma information that normally gets combined with those tastes.

That's why food can suddenly seem bland.

It's not necessarily that your tongue has stopped working.

You're missing part of the sensory information that normally creates the flavor.

A blocked nose is basically doing a version of the jellybean experiment to you, except you didn't volunteer for it.

There's a reason the effect can be so dramatic

Smell isn't just an extra detail added on top of taste.

The two systems interact.

Odors can change how strongly certain tastes are perceived, and tastes can also influence the perception of odors. Researchers have demonstrated these interactions experimentally, including with sweet, salty and sour stimuli paired with different odor compounds.

So flavor isn't assembled in your brain as a neat list:

"Sweet: yes."

"Smell: yes."

"Texture: yes."

Your brain is integrating all of those signals into one experience.

That's why removing one of the major inputs can change the whole thing.

Can you actually identify food using taste alone?

Sometimes.

But it's much harder than people tend to think.

A very salty food is easy to recognize as salty.

Something extremely sour is easy to recognize as sour.

But try identifying several fruit-flavored candies while your nose is blocked and your eyes are closed.

That's a different challenge.

You may know that you're eating something sweet and slightly sour, but several possible foods can fit that description.

Once the aroma comes back, the possibilities narrow quickly.

This is also why scientists can use retronasal smell tests to study people's ability to identify odors during eating. One large study tested retronasal odor identification in more than 500 participants across seven countries and found that retronasal smell performance could be measured separately from ordinary smelling through the nostrils.

So the smell you experience while eating isn't just a strange side effect of chewing.

It's a measurable part of how humans perceive food.

What about food that has a strong texture?

This is where the experiment has a limitation.

Blocking your nose doesn't remove every source of flavor information.

You still have texture.

Temperature.

Basic tastes.

And certain foods produce other sensations that aren't technically taste or smell.

Chili peppers, for example, create a burning sensation. Mint can create a cooling sensation.

So the experiment isn't really testing "taste versus no taste."

It's testing what happens when you remove olfactory information while leaving much of the rest of the eating experience intact.

That's why it's a useful demonstration rather than a perfect laboratory measurement.

Why does warm food usually smell stronger?

Temperature affects the release of volatile compounds from food.

In simple terms, warming many foods makes it easier for aroma compounds to escape into the air.

That's why a hot bowl of soup can smell strongly from across the kitchen while cold soup usually doesn't announce itself quite as aggressively.

During eating, aroma release also depends on what you're chewing, how the food is structured, how much you chew and other physical factors. Researchers studying aroma release during eating describe it as a dynamic process rather than something that happens at one fixed rate.

So temperature is only one piece of the puzzle.

Is smell responsible for 80% or 90% of taste?

You'll see claims like that all over the internet.

I'd be careful with them.

There's no useful universal percentage that says exactly how much of "taste" comes from smell.

The problem is that people are usually talking about flavor, not taste.

And flavor isn't one fixed thing.

Different foods provide different combinations of taste, aroma, texture, temperature and other sensations. People also vary in how strongly they perceive odors and tastes.

What the evidence does support is much more useful than a catchy percentage.

Smell makes a major contribution to flavor, and retronasal smell is particularly important during eating.

That's enough to explain why blocking your nose can turn a familiar food into something surprisingly difficult to identify.

There's a simple way to see the whole thing

Try the experiment with something you know extremely well.

A jellybean works.

A piece of fruit works too.

Chocolate can work.

Have someone give you the food without telling you what it is.

Keep your eyes closed.

Taste it normally.

Then repeat the experiment with your nose blocked.

Don't worry about getting every answer right.

Pay attention to what information disappears.

Then release your nose while you're still chewing.

That sudden return of aroma is the part that makes the whole explanation click.

Your tongue didn't suddenly become better at detecting sugar.

The food didn't magically become more flavorful.

Your brain simply received another stream of information.

That's what you've been calling "taste" all along.

The tongue gives you the basic tastes.

The nose supplies a huge amount of the detail.

Your brain puts the pieces together and gives you what you experience as flavor.

So when a cold makes your favorite meal taste like cardboard, your tongue probably hasn't betrayed you.

Your nose is simply missing from the conversation.