Bananas are a sensitive bunch. Though they can withstand peeling, slicing, chipping and frying, age is not so kind to them. At one time or another, nearly everyone has peeled back the skin of a banana to discover a mushy brown spot inside. But what makes good bananas go bad?

In order to understand banana bruising, first you must understand the banana’s ripening process. Meet ethylene. Ethylene is a hormone found in the peel of the banana.

When you buy a bunch of unripe green bananas at the grocery store, time and ethylene magically transform them into delicious, golden bananas. Unfortunately, ethylene has no stop button. When left uneaten, the ripening process will continue until the banana takes on a “bruised” appearance and eventually turns black.

You can’t prevent the ripening process from occurring, but one way to slow it down is by placing bananas in a cool location. You should also remove them from the bag when you bring them home from the market. Leaving bananas in the bag allows ethylene gasses to build up, causing the bananas to ripen very quickly.

This knowledge can work to your advantage, too! If you have a craving for a banana and the bunch is still green, placing a banana in a sealed bag will speed along the ripening process. Your sweet snack should be ready to eat in about 24 hours.

It’s important to remember to keep bananas out of the fruit bowl and away from other fruits if you want to delay ripening. If you place your bananas in a bowl with other fruits, such as apples or tomatoes (which also rely on ethylene for ripening), you may be surprised by what happens.

Ethylene released by neighboring fruits in the bowl can actually ripen your bananas! In fact, this is where the expression “one bad apple spoils the bunch” comes from. If one apple in a barrel begins to over-ripen and rot, it will cause the surrounding apples to do the same.

This is why fruit farmers pick and ship fruit when it’s still green, long before the ripening process has begun. Shipping under-ripened fruits ensures they are verging on peak ripeness when they hit the grocery shelves — and perfectly delicious by the time they finally reach your dinner plate.


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  1. I’m pulling those bananas out of the fruit bowl as soon as I get home! I am enjoying your wonders, and I think you ought to find a way to promote this to adults for their own enjoyment too.

  2. oh, well I like bananas!! but sometimes they are not all the way done and by that I mean they are not all the way ripe. I heard they are good for you. even if they are not im still going to eat them :)

    • That’s the spirit, jasmine monique’! Bananas ARE good for you! We think it’s great when you love to eat something AND it’s also healthy for you (you win twice)! Thanks for stopping by Wonderopolis today! :-)

  3. So now I can tell my friend that when a banana isn’t “done” she needs to leave it alone for a day. That’s really cool almost as cool as the ice cream sundae with maple syrup and bacon topping.

    • We think that kind of sundae sounds awesome, Kari! Thanks for visiting Wonderopolis today and for your comment! :-)

  4. I haven’t talked to you in a long time because of spring break I hope everyone had a good spring break. Bananas are one of my favorite fruit, do monkeys eat the bruises?

    • Welcome back to Wonderopolis, Brooke! It’s great to say hello again! We had an excellent spring break and we’re glad to know that you enjoyed your time, too! We think monkeys enjoy bananas so much that they don’t even worry about the bruises! They aren’t very picky when it comes to bananas! Thanks for sharing your comment, we’ll see you soon! :)

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  • About a favorite banana snack of a well-known celebrity

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