Sophie Duncan plucks some ripe fruit

17th September 2004 at 01:00
This week's activities will encourage your students to explore how fruit ripens.

Fruit produces a chemical called ethylene. As this gas is released it encourages the fruit to make enzymes. The enzymes convert starch to sugar, ripening the fruit and making it more palatable. The fruit becomes softer as the cell walls weaken.

Bananas are usually harvested when they are green, so that when they arrive in the shops they are ripe. Commercial banana firms may apply extra ethylene gas to help ripen the fruit. Apples and bananas make a lot of ethylene. This is why bananas are often stored away from the other fruit.

This experiment allows you to find out the effect of ethylene on some unripe fruit.

Choose some unripe fruit - strawberries or plums work particularly well.

Place two pieces of fruit in each of three paper bags. Add a ripe apple to the first, a ripe banana to the second, and to the third add nothing at all.

Place the bags in different places (as the ethylene produced by the fruit is a gas, it can travel a long way) making sure they are out of the sun.

Dry storage cupboards work well. Leave the fruit for a day and then examine it. The fruit in the bags with the apple or banana is likely to be riper than the fruit left on its own. Leave it for another day and observe again.

Repeat this until all the fruit is over-ripe.

As the fruit ripens it produces more ethylene. So once you have one ripe piece of fruit, soon all the fruit is ripe. The fruit used as a control will not ripen quickly, but as it does ripen the process speeds up as ethylene is produced.

Log-in as an existing print or digital subscriber

Forgotten your subscriber ID?


To access this content and the full TES archive, subscribe now.

View subscriber offers


Get TES online and delivered to your door – for less than the price of a coffee

Save 33% off the cover price with this great subscription offer. Every copy delivered to your door by first-class post, plus full access to TES online and the TES app for just £1.90 per week.
Subscribers also enjoy a range of fantastic offers and benefits worth over £270:

  • Discounts off TES Institute courses
  • Access over 200,000 articles in the TES online archive
  • Free Tastecard membership worth £79.99
  • Discounts with Zipcar,, Virgin Wines and other partners
Order your low-cost subscription today