Unexpected discovery about blueberry peels

Blue is a rare color in nature and very few naturally occurring organic compounds impart this color to living organisms. So why exactly are blueberries blue? Scientists recently figured out this conundrum - and surprisingly the green color doesn't come from the fruit's peel.

In a study published February 7 in the journal Science Advances, researchers found that small, randomly arranged crystals in the fruit's waxy coating scatter light, causing blueberries to Kumquats have a characteristic indigo appearance.

The blue color of blueberries does not come from the fruit's skin.

Blue color rarely appears in living organisms. The majority of examples, such as bluebells, butterflies and tropical frogs, rely on trickery to produce this coloration (mainly to deter predators). Even blue stones and minerals, such as jade and lapis lazuli, are difficult to come by.

"The blue color of blueberries cannot be extracted by squeezing - because it is not in the juice that can be squeezed out of the fruit," the study said . Blueberries contain strong pigments called anthocyanins , which give them their color. a deep purple-red, completely different from the indigo color of the fruit's skin. However, like most plants, blueberries are covered with a thin layer of protective wax that acts as a water-repellent coating and anti-bacterial barrier. infection".

Scientists suspect the blue color must come from the outside of the fruit. So they removed a sample of this wax and recrystallized it on a piece of cardboard. They were delighted that this created an ultra-thin crystalline coating with the characteristic indigo color of blueberries.

When they looked closely at this layer, they discovered a random distribution of crystalline structures within the wax that help scatter blue and ultraviolet light to create the fruit's characteristic color.

This discovery opens up exciting opportunities for sustainable and biocompatible blue coatings and pigments. This could be used in everything from sensors to construction to car paint, the researchers write in the study.