Ripening Fruit Rapidly!

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(Note: this is not an experiment—because you can eat the results. This is a kitchen project that shows how science is part of our everyday lives!)

If you lived right next to a fruit tree, you would be able to pick a piece of fruit at exactly the peak of ripeness. But, most of us don’t live in orchards, so we get our fruit from a store. Many times, fruit arrives at the store before it is ready to eat. No problem—we take it home and let it finish ripening in our kitchen. But sometimes, that process takes longer than we would like. Is there a way to speed up the process?

First, let’s talk about what happens when fruit ripens. A number of chemical reactions occur. Probably the most noticeable change us that starches in the fruit are changed into sugars. This change makes the fruit taste sweeter and have a more pleasant texture—unripe fruit is often described as mealy. Other reactions cause color changes, make the fruit less acidic (less tart), and softer.

How does the fruit know when to ripen? It’s complicated, but exposure to ethylene gas (a simple organic molecule) turns on enzymes in the fruit that create the ripening process. So, it’s possible to use ethylene gas to ripen fruit. But, how can we get ethylene gas to use in our kitchens? We will use fruit! That’s right—many types of fruit release ethylene. If we put fruit together in an environment that will capture the ethylene gas, the fruit should ripen faster.

In fact, the expression, “one bad apple spoils the whole bunch” is actually based on science! Damaged fruit produces more ethylene, so having a bruised apple in the bag can cause all of the apples to spoil more quickly. Even when people are not officially performing experiments, they are still acting like scientists—making observations and developing theories.

In this project, we investigate whether storing a green banana by itself in a closed bag (to trap ethylene) ripens faster than a banana left on the counter. We also look at whether storing the banana with another piece of ruit (apple or orange) affects the ripening time. The banana left on the counter is very important because it is our experimental control. We will compare the speed that the bananas stored in a bag/with other fruit with the banana left on the counter.

Other factors affecting ripening can also be investigated using this same type of procedure. Try ripening different fruits like avocados or pears instead of bananas. Or you could try using different places of storing the banana like a colder basement or a warmer windowsill. See if the type of bag—paper or plastic—affects the results. When you’re done, you may have decided on a new way to store fruit at home.

Rapid Ripening

Materials

Green bananas

Zipper top plastic bags

Other fruit (apples and oranges work well)

1. Pick several bananas that are similarly unripe.

2. Make observations—the bananas should all have a similar appearance.

3. Set aside one banana. This banana will be the control.

4. Put one banana in a bag by itself. Be sure to seal the bag completely!

5. Put one banana in a bag with another piece of fruit. Be sure to seal the bag completely. Repeat with any other fruit you have to test.

6. Continue to make observations every day. Does one of the bananas seem to ripen faster than the others?

7. This project can be repeated with different fruits or conditions. Find the best way to ripen fruit!