How do we taste food?

1. Zoe pops a strawberry into her mouth. At once she knows: sweet, a tiny bit sour, and definitely strawberry. Two of her senses are working together. Let us find out how.
2. Look closely at a tongue. It is covered in little bumps. Tucked into the sides of the bumps are taste buds, far too small to see. You have thousands of them.
3. A taste bud looks like a tiny onion. Chewing mixes food with saliva, and tiny bits of food slip in through a hole in the top. There they touch the tips of the taste cells.
4. Taste cells come in five kinds, one for each taste: sweet like sugar, sour like lemon, salty like pretzels, bitter like dark chocolate, and savory like soup. Each kind sends its own signal along a nerve.
5. But the tongue cannot say which fruit it is. As Zoe chews, smell particles from the strawberry float up the back of her throat into her nose, to the smell patch at the top.
6. The brain mixes the two messages. Sweet from the tongue plus strawberry from the nose makes strawberry flavor. If Zoe pinches her nose, the smell cannot get through, and she tastes only sweet.

We can see inside Zoe's mouth and nose. The magnifying glass shows one taste bud, much bigger. Tap every part.

• Tongue. A strong, bendy muscle. It moves food around your mouth, and its whole top surface can taste.
• Taste bud. A tiny bundle of taste cells, shaped like an onion and hidden in the side of a bump. You have thousands.
• Taste hole. The little opening at the top of a taste bud. Food bits dissolved in saliva get in through it.
• Taste cells. The cells that do the tasting. Each one senses one of the five tastes and sends a signal when its taste arrives.
• Taste nerve. Nerves carry the signals from the taste buds to the brain.
• Smell's back door. The back of your mouth joins the back of your nose. Smells from the food you are chewing float up this way.
• Smell patch. The smell patch at the top of the nose. It tells strawberry from banana, which the tongue cannot do.
• Brain. The brain joins the taste message and the smell message into one flavor, and remembers it for next time.

Choose a food and drag it to Zoe's mouth. Watch what the tongue says and what the nose says. Then tap her nose to pinch it and try the two candies again.

Experiment: Zoe pinches her nose and eats a strawberry candy. What will she notice?

1. Give Zoe the strawberry candy, then the banana candy. What does her tongue say each time? What does her nose say?
2. Tap her nose to pinch it. Give her both candies again.
3. Let go of her nose while the candy is still in her mouth.

What we found: With her nose pinched, both candies are just sweet, because the tongue sends the same message for both. Only the nose can tell strawberry from banana. Flavor needs taste and smell together.

Turn on JavaScript to try it yourself.

Make each food Zoe is thinking of. Switch on the right tastes for her tongue, choose the right smell for her nose, then press Taste it. For 3 stars, make no mistakes.

Stick out your tongue and look in a mirror. Those little bumps are not taste buds, but the taste buds are hiding in them. Each taste bud is a tiny bundle of taste cells, shaped like an onion, with a small hole at the top. You have thousands of them, all over your tongue.

When you chew, your saliva dissolves some of the food. The dissolved bits slip into the taste buds and touch the taste cells. There are five kinds of taste cell, for five tastes: sweet, sour, salty, bitter and savory. Sweet tells you a food has sugar for energy. Bitter and very sour can be warnings that a food might be bad for you. Every part of your tongue can sense all five.

But five tastes are not enough to explain all the flavors you know. Strawberry candy and banana candy are both simply sweet to your tongue. The difference comes from smell. As you chew, smells from the food float up the back of your throat into your nose. Your brain mixes the taste message and the smell message into one flavor.

That is why food seems dull when you have a stuffy nose. The coloring book comparison is close but not perfect: flavor also depends on how food feels, how warm it is and even how it sounds when you crunch it. Your brain uses all of these clues at once.

Key words

Taste bud

A tiny cluster of taste cells in the tongue, with a small opening at the top.

Saliva

The watery liquid in your mouth. It dissolves food so that you can taste it.

Umami

The savory taste of foods like broth, cheese and tomatoes.

Aroma

The smell of a food.

Flavor

Taste and smell mixed together by your brain.

Check your thinking

1. What two senses does your brain mix together to make a flavor?

   Show the answer

   Taste and smell. The tongue gives the basic taste, and the nose gives the smell. Together they make the flavor.

2. With your nose pinched, why is it hard to tell a strawberry candy from a banana candy?

   Show the answer

   Both just taste sweet, and the smell that tells them apart is blocked. The tongue sends the same message, sweet, for both candies. Only the nose can tell which is which.

3. Which of these is NOT one of the five tastes your tongue can sense?

   Show the answer

   Strawberry. Strawberry is a flavor, made from sweet and a little sour on the tongue plus a smell in the nose. The five tastes are sweet, sour, salty, bitter and savory.

4. Why does very dry food on a very dry tongue have almost no taste at first?

   Show the answer

   Food has to dissolve in saliva before it can get into the taste buds. The dissolved bits slip into the tiny holes of the taste buds. That is one job of your saliva.

5. Where on the tongue can you taste sweet things?

   Show the answer

   Everywhere that has taste buds. Every part of the tongue with taste buds can sense all five tastes. The old tongue map is a myth.