Try this: Going bananas

What’s happening?

There’s a good chance the bananas and tomato you put together in the paper bag will ripen before the other fruit. Why is that?
Technically, a plant’s fruit is simply its ovaries; the organ containing its seeds. Different plants spread their seeds in different ways – some drop them to the ground, and don’t want animals to eat them, while others love birds or mammals munching on them, as this helps spread the seeds further.
Plants that need the help of birds and animals will often fill their fruit with nutrients in the form of sugar to make them more attractive to fruit eaters.
If a plant doesn’t want their fruit eaten, there are many ways of preventing animals from tucking in, such as covering the fruit with spikes or making it taste bad. Bananas, on the other hand, have a neat trick. A bunch (or ‘hand’) of bananas will ripen all at once.
It does this by releasing a gas called ‘ethylene’ (C2H4). This hormone causes nearby fruit to ripen as well, helping the banana bunch to all ripen at the same time.
It’s unlikely a herbivore will eat all the ripe bananas in a single sitting, giving some of them a chance to drop and plant their seeds.
You might notice that the bananas you eat don’t have seeds. That’s because this fruit has been cultivated for thousands of years, to the point that the bananas we grow in large plantations today all come from cuttings called ‘suckers’ rather than seeds. But the fruit still produces ethylene.

Applications

Have you heard of the phrase ‘one bad apple can spoil the bunch’? Transporting fruit over a long distance takes time. Between picking and selling, it could be several days. In the meantime, any ripe fruit carries the risk of going bad and ruining the shipment.
To make the fruit all ripen at the same time, growers will pick the fruit before it’s ripe then the transporters will spray the fruit with ethylene on arrival at their destination to make it ripen in time for you to buy and eat it.
Of course, while the ethylene isn’t toxic for us, all of the carbon dioxide released by transporting fruit long distance isn’t exactly beneficial for the environment. Buying locally-grown fruit ensures the energy goes into your body with less energy needed for shipping it to your corner store.

You will need

  • 3 unripe bananas
  • 4 unripe tomatoes
  • 2 paper or plastic bags

What to do

  1. Put two bananas and an unripe tomato together into the paper bag.
  2. Put the two tomatoes into the second paper bag.
  3. Put a fourth tomato off to one side on its own.
  4. Place the third banana off to one side on its own.
  5. Check the fruit over the next few days. Which ones ripen first?