Washington DC, Feb. 8 -- Researchers at the University of Bristol have discovered that blueberries' blue hue is caused by tiny exterior structures in their wax coating.

This applies to lots of fruits that are the same colour including damsons, sloes and juniper berries.

In the study, published in Science Advances, researchers show why blueberries are blue despite the dark red colour of the pigments in the fruit skin. Their blue colour is instead provided by a layer of wax that surrounds the fruit which is made up of miniature structures that scatter blue and UV light. This gives blueberries their blue appearance to humans and blue-UV to birds. The chromatic blue-UV reflectance arises from the interaction of the randomly arranged crystal...