In this activity, students learn that our perception of flavours can be affected by our sense of sight. What we see influences what we taste!
In a world of lime-flavoured tortilla chips, 100s of different jellybeans and countless flavors of ice cream, our sense of taste might seem to exist purely for pleasure. Instead, the ability to distinguish bitter from sweet does far more than help us choose between light and dark chocolates.
Sweetness is a signal that what we are eating will give us energy, while bitterness can warn that we may be about to swallow something toxic. In our primordial past, long before nutritional labelling, using such cues was essential to survival, as it still is for animals living in the wild.
Identifying tastes is the brain's way of telling you about what is going into your mouth, and in some cases, keeping you safe. One example is drinking milk that has gone off and turned sour. When the milk hits the taste buds, they send nerve impulses to the brain: "Milk coming in—and it tastes weird.” Once the brain unscrambles the nerve impulses, it recognizes the taste as a potentially dangerous one, and you know not to drink the milk.
How do you know how something tastes? Each taste bud is made up of gustatory cells (taste-sensing cells), which have sensitive, microscopic hairs called microvilli. Those tiny hairs send messages to the brain, which interprets the signals and identifies the taste for you.
The average person has about 10,000 taste buds and they are replaced approximately every 2 weeks. As a person ages, some of those taste cells are not replaced. An older person may only have 5,000 working taste buds. That is why certain foods may taste stronger to children than they do to adults.
Tricking taste buds
Some things can make your taste bud receptors less sensitive, such as cold foods or drinks. An ice pop made from your favorite juice does not taste as sweet as plain juice. If you suck on an ice cube before you eat a food you dislike, you do not notice the bad taste. The way food is prepared also makes it taste different: compare raisins and grapes; boiled, scrambled and poached eggs; potatoes that have been mashed, baked, roasted, boiled and fries.
If food has a different colour than normal, the brain will get mixed signals from the mouth and the eyes. The food will seem to taste different. In fact, food companies add colour to food to influence what it tastes like. People like to see foods in colours that they expect. Without colour additives, colas would not be brown, margarine and cheese would not be yellow or orange, and mint ice cream would not be green. Colour additives are recognized as an important part of practically all foods we eat.