Nicholas Turro of Columbia University in New York, Bernhard Krautler of the Institute of Organic Chemistry at the University of Innsbruck, Austria, found that when chlorophyll ages and begins to disintegrate in banana peels, it does not change color in the spectrum of visible light, instead, it glows blue when observed under ultraviolet light.

Left picture is banana in daylight while right picture is banana that glows blue in UV light

Chlorophyll is the molecule that allows life on Earth. It is the integral part that makes plant can take a mixture of carbon dioxide, water and sunlight so they can be converted to oxygen, sugars and starches. The chlorophyll break down is a major contribution to the color changes in fall leaves, and also ripening apples and pears. But in ripening and rotting bananas, chlorophyll fades to be unique fades color, causing yellow bananas to glow blue when observed under ultraviolet light.

Light-blue glowing rings surround the dying cells on the skin of a ripe banana

Because the glowing molecules occur in close proximity to dying tissue, they promise for good sign for further study of the way organisms cleanse themselves of dying cells, or even programmed cell death as in cancer cells. And we hope it also gives good sign for cancer research in human body.