Study: Ripe bananas look blue in UV light
INNSBRUUCK, Austria (UPI) — An Austrian-led team of scientists has discovered ripe yellow bananas glow an intense blue when viewed under ultraviolet light.
Researchers from Austria’s University of Innsbruck and scientists from Columbia University in New York said the blue glow results from the degradation of chlorophyll that occurs during ripening.
The team, led by University of Innsbruck Professor Bernhard Krautler, said the usual yellow appearance of bananas is mainly the result of carotenoids. Under normal light, the natural pigments appear yellow. Under UV light, also known as black light, ripening bananas appear blue instead of yellow.
“Surprisingly, this blue luminescence apparently has been entirely overlooked,” said Krautler.
He suggested two explanations as to why the breakdown of chlorophyll occurs differently in bananas than in other higher plants, including even banana leaves. “In contrast to humans, many of the animals that eat bananas can see light in the UV range. The blue luminescence of the banana fruit could give them a distinct signal that the fruit is ripe.”
Or, he added, perhaps the chlorophyll degradation products also serve a biological function for the banana, helping prolong the viability of the ripening fruit.
The research appears in the journal Angewandte Chemie.
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Copyright 2008 by United Press International
