Researchers at the University of Bristol have revealed that small external structures in the waxy layer of blueberries give them their blue colour, as is the case with plums, plums and juniper berries.
In a study published in the journal Science Advances, researchers showed why blueberries are blue even though the skin has a dark red pigment. Instead, its blue color is caused by a layer of wax that surrounds the fruit and is made up of miniature structures that diffuse blue and ultraviolet light.
This makes blueberries appear blue to humans and ultraviolet blue to birds. Blue-UV reflection results from the interaction of the randomly arranged crystalline structures of the epithelial wax layer with light. The blue in blueberries cannot be ‘extracted’ by crushing them, as it is not found in water, explains Rox Middleton, a researcher at the Bristol School of Biological Sciences, in a statement.
Pressed pigments can be extracted from fruits. That’s why we know there must be something strange about the color. So we removed the wax layer and recrystallized it onto the cardboard, and by doing so we were able to create a new blue UV layer.
The ultrafine dye is about 2 microns thick and, although less reflective, has a light blue color and reflects UV rays well, perhaps paving the way for new dyeing methods.
This shows that nature has evolved to use a really clever trick, the researcher added, which is an ultra-thin layer for an important dye. The team now plans to look at easier ways to reproduce the coating and apply it.
This could create a paint that is more durable, biocompatible and even edible, UV reflective and blue in color. Additionally, these coatings can have many of the same functions as natural biological coatings in protecting plants.
