Have you ever wondered how certain fruits are such vibrant colors? Scientists globally have also pondered such characteristics. Some people think that objects obtain their colors by simply having the pigment inside. However, how our eyes perceive color is much more complicated than simply seeing the pigmentation.

Recently, research has been conducted on the color of blueberries. Blueberries are considered to be a “bloom” fruit, in that it has an epicuticular wax layer and dark pigmentation. This color does not come from smushing the fruit and watching the juice emerge, which led researchers to wonder where exactly it does come from. Researchers have discovered that blueberries are covered by a thin, waxy coating that is two microns thick. The researchers discovered this by removing the waxy layer and recrystallizing it to view the particles within the layer itself.

Within this layer, there are scattered particles in a random crystalline structure that reflect blue and UV light. Photons of light have certain pigments, and only a few of which are visible to humans. The photo below depicts which light is visible to humans. It is also notable that the pigment in blueberries reflects UV light, which is visible to birds.

FIO117: Figure 8.1

This directly relates to our AP Bio Photosynthesis Unit. In this unit we learned the reason why leaves are green. This is because leaves contain certain pigments (one being chlorophyll a) that absorb all wavelengths of light except for green, which is reflected.

Additionally, we learned in AP Bio that leaves are surrounded by a non-polar, waxy substance. This is the same on blueberries. It is interesting that learn that water will not easily penetrate through the skin of leaves as well as certain fruits due to the repulsion of non-polar and polar substances.

Do you know of any other epicuticular fruits? Can we investigate their pigmentation as well?

Print Friendly, PDF & Email