Kitchen Science Activities
Roberta Gibson

Did you know you had a science laboratory in your kitchen? Here are a few activities to get you started in the fun field of food science. Just remember that you should always ask an adult before using the kitchen and ask for guidance when using hot appliances such as the stove or popcorn poppers, and sharp implements, such as knives.

The Real Thing: Butter

I bet most of you know butter comes from cows’ milk, but how is butter made? You will need a pint of cream and a pint of skim milk. Keep refrigerated until use. If you have two clear containers with tight-fighting lids, pour the cream into one and the skim milk into the other. If not, just leave them in their unopened carton. Now shake the containers or cartons. Ask a friend or family member to help too. Do you see or feel the changes? After about twenty minutes, open the containers. Has the cream formed lumps? Those lumps are butter.

The fat in the cream began to form lumps as the shaking gently warmed up the cream. The leftover liquid is called buttermilk. The skim milk lacks fat and should have not changed. Go ahead and try your butter.

Now for Some Popcorn

Ever wonder how a small, hard kernel of popcorn could become that fluffy white stuff? The secret is water!

You will need one cup of un-popped popcorn, four bowls, a hot air popcorn popper (or other method for popping corn), a cookie sheet, a measuring cup, water, a colander, a pencil and paper to record your results, and access to an oven.

Start by placing 1/3 cup of the un-popped popcorn in a bowl. Add one cup of water and then set aside for one hour. Spread 1/3 cup (un-popped popcorn) on a cookie sheet and place in an oven heated to 200 degrees F for one hour. In the meanwhile, pop the remaining 1/3 cup and catch the results in a bowl. You should label the bowl “standard.”

Drain the water from the first batch with the colander and then pop it in the same manner. Catch the results in another bowl. Label this bowl “wet.” Remove the second batch from the oven. Have any kernels popped? Now pop that batch and catch the results in a third bowl. Label that bowl “dry.”

Measure the amount of popped corn in each bowl using the measuring cup. Count the un-popped kernels. Look at the texture and size of the kernels.

In general, the more water the kernels contained, the better they should have popped. Can you have too much water? Try leaving 1/3 cup of popcorn in water overnight. How does this affect the kernels’ ability to pop?

How Now Brown . . . Fruit?

Have you ever set down a banana you were eating and come back to find it brown and unappetizing? The reason this occurs is that some fruits and vegetables contain colorless substances called polyphenols that turn brown when exposed to oxygen. The process is called oxidation. Let’s see whether we can stop or slow this reaction.

You will need a banana, an apple, a potato, and 2 or 3 strawberries (avocado may be substituted for the first three and kiwi for the strawberry). You will also need 2 tablespoons of granulated sugar, 2 tablespoons of lemon juice, 2 tablespoons of water, 4 paper plates, a paring knife, and a marking pen. Cut each fruit or vegetable into eight roughly equal pieces. Place two of each kind on each plate. Label the first plate “sugar” and quickly sprinkle the fruit and vegetables on the plate with the granulated sugar. Label the next plate “lemon juice” and cover the fruit and vegetables with lemon juice. Repeat with the next plate, substituting water for the lemon juice. Leave the last plate alone and label it “plain.”

Let the foods sit uncovered at room temperature for thirty minutes. Think about what you expect will happen. Now look at the plates. Which food turned darkest? Which are closest to their starting color? Taste some (all are still safe to eat). Has the flavor changed?

What should have happened is that the lemon juice with vitamin C (an antioxidant) should have protected the fruit from browning. The sugar and water may have prevented some browning by acting as a barrier to the oxygen. The apple, banana, and potato on the plain plate should have turned brown, but the strawberry should not have. Do you think that is because strawberries lack polyphenols or because they contain antioxidants? How would you test that?

The number of experiments you can perform in the kitchen are endless. I hope this has inspired you to do some food science of your own!

Copyright December 2001
Originally published in January/February 2002 issue of HELM (Home Education Learning Magazine)