Carotenes are the class of compounds responsible for the orange color of carrots for which they received their name. They are also behind the color of autumn leaves and many fruits and vegetables such as apricots, melons, pumpkins and many more. Carotenoid-rich diet reflects on the orange/pink-colored feathers of flamingoes as well. Retinol is another member of the carotenoid family more commonly known as Vitamin A.
These beautiful colors are a result of carotenes absorbing the blue light as the color that we see is the opposite of what is absorbed by the object. Absorbing the blue light is only possible if the organic molecule is highly conjugated. This, in simpler words, means alternating double or triple bonds which allows the transition of electrons to excited states promoted by the visible light.
