Do Onions Ripen Other Fruits?

(Last Updated On: January 26, 2023)

If you’ve ever gotten super-green bananas from the grocery store your friend (or local internet stranger) might have told you to store some onions next to them. Or you made the mistake of storing onions with all your fruits and vegetables because you put them all in a pile, but then they all over-ripened like… Immediately. Maybe it’s just another way onions go about making you cry, but do onions actually ripen other fruits?

Further Reading: Why Do Onions Make You Cry?

Ethylene Gas

When fruits ripen they broadly increase their sugar content and reduce their acidity. You probably knew that from fruits being sweeter when ripened.

Ethylene is a hydrocarbon that facilitates the ripening of fruits. It’s actually just two carbon atoms and four hydrogen atoms (making it the simplest possible alkene, if you’re chemically inclined). As a gas, it’s colorless and flammable, so maybe don’t be spraying large amounts of it into your house. You also can’t breathe it, so there’s that. In commercial industry, we use a lot of ethylene, but mostly for making plastic.

When fruits are ready to ripen, there’s a surge in ethylene production. Fruits are also still sensitive to ethylene after ripening, so you can go from ripe to rot pretty quick. Long short: ethylene makes fruits ripen. 

You might be wondering how plants regulate this, since timing for fruits is actually quite crucial. The window for when fruits are good to eat is quite small, and plants need to time the ripeness of their fruits with the habits of the animals that eat them; often this is tied to the seasons. Turns out, plants actually have a kind of “master switch” that decides whether or not a fruit should ripen. This not only dictates whether or not ethylene is produced, but also whether or not the fruit will be sensitive to ethylene. It’s why stuffing a banana in the bag doesn’t work all the time. 

Because ripening is basically just rotting but early, ethylene is also a plant stress tool. When a part of a plant is damaged, like a leaf of branch, ethylene may be produced to force the damaged part to rot and fall off—like a form of self-amputation.

Onions and Ethylene

You’ve probably figured out by now that onions are ethylene producers, so they’re going to hasten the ripening of ethylene-sensitive fruits and vegetables. So short answer, yes, onions can ripen other fruits. What makes onions a little special is that they don’t seem to be as sensitive to ethylene; being around ethylene actually might suppress the sprouting of onions. The problem with onions specifically, is that onions also grow fungi that promotes decay, which is less of a problem for the onion since it has quite a long shelf-life—but it’s bad news for your other produce. 

Apples, pears, or really anything that grows on trees typically also produces a lot of ethylene. Tree fruits are also particularly sensitive to ethylene, along with bananas, peppers, and tomatoes. Lettuce, squashes, and cucumbers are among the many forms of produce that might not be the biggest ethylene producers, but are still quite sensitive to ethylene gas. 

Speaking of onions, see if you know which countries are producing the most here

About the Author:

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Kyler is a content writer at Sporcle living in Seattle, and is currently studying at the University of Washington School of Law. He's been writing for Sporcle since 2019; sometimes the blog is an excellent platform to answer random personal questions he has about the world. Most of his free time is spent drinking black coffee like water.