The secrets of shiny fruit unlocked

12 Sep 2012, 5:25 am   -   Source: AAP

Scientists have discovered how Pollia, the world's shiniest fruit, retains its iridescent colour for centuries.

Scientists have discovered how Pollia, the world's shiniest fruit, retains its iridescent colour for centuries.

The shimmering fruit is not actually juicy or particularly edible-it contains mostly hard seeds-but its brilliantly-coloured blue and purple exterior, with tiny pointillist-like dots of red, green, and orange, has attracted scientists into trying figure out how it gets its shine.

With the help of UK Kew Gardens' Paula Rudall, researchers from the University of Cambridge tracked down a Pollia plant from Ghana in 1974 that is still as bright as ever and studied it thoroughly, Discover Magazine reported.

According to their findings, published Monday in the Proceedings of the National Academy of Sciences in the United States of America (PNAS), the fruit shines at a structural, cellular level.

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The cells in the Pollia condensata are made up of walls of coiled-up cellulose strands that reflect light, Nature explained. The measure of the spaces between the strands allow light to reflect at different wavelengths, which is responsible for the fruit's iridescence.

"The optics are impressive," said Silvia Vignolini, a physicist at the University of Cambridge and one of the authors of the study. "There are no previous examples of this in nature. It is 10 times more intense and bright than any colour achieved with a pigment."

Though the concept of structural colour has been found in animals-like in peacock feathers, beetle carapaces and butterfly wings-this is the first instance of structurally built-in colour in a fruit.

Scientists speculate that the intensity of the colour may be the plant's adaptation to get birds to eat the fruit and spread the seeds, New Scientist reported.

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