Taste test
Smelly sweets or tasty treats? Our tongue has lots of taste buds that allow us to taste food, but let’s sniff out some facts about the role of the nose in tasting food.
What you need
- plastic cups
- food colouring
- a variety of fruit juices (e.g. orange, apple, pineapple, lemon, orange and mango)
What you do
- Pour a small amount of each juice into a different plastic cup.
- Add a few drops of red, blue or green food colouring to disguise the real colour of each juice.
- Ask someone to taste each juice and identify the flavour.
- Which juice is the easiest to identify?
- Try the test on someone else, but ask the person to hold his/her nose while tasting the juice.
- Did s/he find it difficult to identify the flavours?
What's happening?
Did you know?
Butterflies have taste receptors in their feet!
The surface of the tongue is covered in tiny bumps called papillae. The taste buds, which are located in folds on the papillae, are lined with sensory receptor cells that respond to chemicals in the food we eat. The receptor cells send messages to the brain that give us the sensation of taste.
The smell of a food is also an important part of its taste. If we can’t smell a food, we can’t really taste it properly. Foods smell because they release odour molecules, which are chemicals that evaporate into the air. Inside the nose, there are specialised sensory cells called ‘olfactory receptors’ which are responsible for detecting odour molecules and sending signals to the brain to give us the sensation of smell. When you chew food, the food releases odour molecules which travel into the nose where they are detected by the olfactory receptors.
When you have a stuffy nose, or when you hold your nose, your nose isn't able to receive the chemicals that trigger the olfactory receptors, so your food doesn't seem to have much flavour.
In humans there are four basic taste senses: sweet, sour, salty, and bitter. The receptors for these four basic tastes have their areas of greatest concentration on different parts of the tongue; sweet and salty on the front, bitter on the back, and sour on the sides. A few substances stimulate only one of the four types of receptors, but most stimulate two, three, or four types to varying degrees. The sensations we experience are thus produced by a blending of the four basic sensations in different relative intensities.
Investigate!
Can you confuse someone’s nose and mouth to feel like s/he is eating an onion when s/he is really eating an apple? Try this on a friend (don’t show these things to your friend but you will need a blindfold, a piece of peeled apple and a cut onion). Blindfold your friend, hold the onion under their nose and ask them to breathe in through their nose. Now feed them the piece of apple and ask them what they are eating. Did they think they were eating an onion? What other combinations of smelly foods and less-smelly foods could you try?
