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Taste-Smell Connection

Taste is truly a sensory bonanza, but is it totally limited to the tongue?

We know that some things affect taste, and having a cold is the most familiar example. We do not taste food as well when our heads are stuffy and our noses are clogged. Does that mean smell contributes as much or more to taste as the taste buds?

Researchers have found that when volunteers wore nose plugs, their sense of taste was less accurate and less intense than when they tasted the food without the nose plugs. Smell did appear to make a difference. However, nose plugs did not completely block all ability to taste. Because the nose and throat essentially share the same airway, chewing some foods allows aromas to get the nose through the back of the mouth even when the nostrils are closed.

Our sense of smell in responsible for about 80% of what we taste. Without our sense of smell, our sense of taste is limited to only five distinct sensations: sweet, salty, sour, bitter and the newly discovered “umami” or savory sensation. All other flavours that we experience come from smell. This is why, when our nose is blocked, as by a cold, most foods seem bland or tasteless. Also, our sense of smell becomes stronger when we are hungry.

Objectives

  • Explore the connection between different senses.

  • Outline how the body’s taste buds detect different tastes.

  • Identify and explore the five basic senses.

Materials

  • Per Student Pair:
    6 pieces cubed apple
    6 pieces cubed pear (with peel/skin removed)
    6 pieces cubed potato (with peel/skin removed)
    coloured toothpicks

Key Questions

  • Why is it difficult to taste your food when you have a cold?
  • Why are taste and smell connected?

What To Do

Set up

  1. Remove the peel or skin from the apples, pears and potatoes.
  2. Cut them into small cubes so they all look the same (ensuring that you know which is which).
  3. Spear each piece with a toothpick (HINT: a different colour toothpick for each fruit will prevent confusion).

Teacher tip: Check students’ allergy information before selecting the fruit and vegetables.

Activity

  1. Give each student 3 different cubes to eat and tell them to identify the fruit or vegetable they are eating with their eyes closed (working in partners will facilitate this process).
  2. Give each student 3 extra different cubes, tell them to close their eyes and hold their nose while eating them and then guess what they are eating (again using partners if necessary).
  3. Ask the students why it is so difficult to identify what they are eating when they have no visual clues i.e. no fruit shape or skin colour.
  4. Ask the students why it is so difficult to identify what they are eating without visual clues and when they hold their nose.
  5. Explain that they usually rely heavily on their vision to make sense of their surroundings, so taking away visual clues can sometimes trick the brain. It is very hard to distinguish between apple, pear and potato when they all look the same. Taking away the sense of smell then makes it even harder to distinguish between all three. The nose and mouth are connected through the same airway which means that you taste and smell foods at the same time. Their sense of taste can recognize salty, sweet, bitter, sour and savoury (umami), but when you combine this with the sense of smell they can recognize many other individual ‘tastes’. Take away smell and sight and you limit your brain’s ability to tell the difference between certain foods.

Extensions

  • Explore which sense is more dominant - taste or smell? For some foods, smell might overwhelm our recognition of taste. Blindfold a volunteer and ask them to try a slice of apple. Tell them you want them to smell the flavor of the food while they are eating it. Put a slice of fresh onion under their noses when they start to taste the apple. Do they taste apple or onion? Discuss what this result says about our sense of smell. Try other food combinations if time allows.