How do we know?
↻ One of the pages with a moving picture
Peas in a lab grew sideways, and a gas was to blame.
- Ripening bananas give off an invisible gas called ethylene. It tells fruit to ripen.
- Once ethylene starts, the fruit makes even more of it, so ripening speeds up. The peel turns yellow and the fruit gets softer.
- As the peel’s cells age and break, an enzyme mixes with other chemicals and oxygen in the air. That makes brown spots.
- Brown spots don’t make a banana harmful to eat. Bananas are tropical, so cold fridge air hurts the peel’s cells and turns it brown.
In 1901 Dimitry Neljubow grew pea seedlings in two boxes: one got outdoor air, the other got air from his lab. The lab peas grew sideways and swelled up. The cause was ethylene in the lamp gas leaking in his lab.
Bananas are tropical, so cold fridge air hurts the peel’s cells and turns it brown.
The giant wild banana, the world’s biggest herb plant, can grow 300 bananas in one bunch.
Wow number
300 bananas can grow in one bunch on the giant wild banana, the world’s biggest herb plant!
Myth or fact?
A banana with brown spots is bad to eat. Myth. Browning does not make food harmful to eat.
Bananas can keep ripening after they’re picked. Fact. Bananas, apples and avocados all ripen after harvest.
Think about it
Why might a store keep green bananas away from ripe ones?
Where in the world?
St. Petersburg, Russia where, in 1901, Dimitry Neljubow of the city’s Botanical Institute discovered ethylene’s effect on plants — 59.9311° N, 30.3609° E.
Where these facts come from
Every number on page 86, and who measured it
This page tells us about the giant wild banana, the world's largest herb, and its huge bunches.
Largest herb — Guinness World Records, which keeps lists of world records
guinnessworldrecords.com/world-records/86951-largest-herb
We checked it on 31 October 2026
This page tells us how the gas ethylene makes fruit ripen.
Ethylene and the Regulation of Fruit Ripening — University of Maryland Extension, which teaches about farming and food
extension.umd.edu/resource/ethylene-and-regulation-fruit-ripening
We checked it on 31 October 2026
This page tells us why fruit turns brown and that browning isn't harmful.
Fruits Gone Bad? Discover Enzymatic Browning — Scientific American, a science magazine
scientificamerican.com/article/fruits-gone-bad-discover-enzymatic-browning
We checked it on 31 October 2026
This page tells us how Dimitry Neljubow discovered ethylene with pea plants in 1901.
The Peas that Smelled the Leaky Pipe — Smithsonian magazine, from the Smithsonian museums
smithsonianmag.com/arts-culture/the-peas-that-smelled-the-leaky-pipe-110510118
We checked it on 31 October 2026
Has this changed?
Why bananas get brown spots is not going to change.
What does change is each banana: the more it ripens, the more brown spots it gets.
Words from this page
- ethylene
- An invisible gas that ripening fruit gives off. It tells other fruit to ripen too.
- ripen
- To get soft, sweet and ready to eat.
Try it!
Test a cold banana.
1. Get two bananas that look the same. 2. Put one in the fridge and leave one on the counter. 3. Check both every day for a few days. Draw what you see.
What happens: the fridge banana’s peel turns brown all over, because the cold damages its cells.
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