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Blue Bananas

December 1, 2008

You might not think by looking at them that bananas are really blue.


Glow-in-the-dark bananas….I’m Bob Hirshon and this is Science Update.

You’ve seen blueberries, but what about blue bananas? Scientists have discovered that as bananas ripen, they glow a fluorescent blue color under ultraviolet light. Organic chemist Bernhard Kreitler of the University of Innsbruck in Austria explains that chlorophyll– the compound responsible for plant growth—breaks down into fluorescent compounds when bananas stop growing and start to ripen.

BERNHARD KREITLER (University of Innsbruck, Austria):
These fluorescent compounds in the banana peel…luminesce; they shine blue light when you irradiate them with black light, the light from ultraviolet that we can’t really see.

He says some banana-eating animals can see ultraviolet light; so being fluorescent might aid seed dispersal. Whatever the reason, the discovery is sure to become a staple of junior high school science labs everywhere. I’m Bob Hirshon, for AAAS, the science society.