Green, red and yellow apples brighten up the shelves of the greengrocer. But does the different color of the skin of apples also determine different properties? Yes, as we will see. In particular, some antioxidant and anti-inflammatory substances that determine the color of the peel and also some properties vary while the nutritional profile, therefore the quantity of water, fibers, the presence of vitamins A and C and mineral salts such as potassium remains constant (Nicklas et al, Food Nutr Res, 2015). But let's understand better.
All apples, of all colors, have two antioxidant substances in the skin, which belong to the carotenoid family, such as lutein and beta carotene, and chlorophyll (Delgado Pelayo et al, Food Research International, 2014). The maturation processes then lead some pigments to degrade or form. In the case of the green-skinned apple, in particular, chlorophyll is the prevailing pigment. Not only that, a study observed that the green apple is the type of apple with the highest content of pigments, and therefore substances that give color, immediately followed by the red and then yellow apple. But pigments don't just give color, they are also a source of valuable health properties and therefore green apple is a truly beneficial choice! In fact, chlorophyll counteracts the damage of free radicals and the aging processes, it is anti-inflammatory and antitumor counteracting cellular degeneration (Wang et al, Peer J, 2016 - Simonich et al, Food Chem Toxicol, 2009).
The red apple is an apple that contains carotenoids and chlorophyll, which, however, undergoes changes during the ripening process. In particular, chlorophyll degrades and other antioxidant substances are formed, called anthocyanins, which prevail and give the red color (Jing et al, PLoS One, 2016). Anthocyanins are also substances with a powerful antioxidant action, capable of protecting DNA, are anti-inflammatory, strengthen blood vessels, counteract tumor formation and proliferation. Not only that, anthocyanins also act on the brain, help improve memory and have a preventive effect on age-related cognitive decline (Lila et al, J Biomed Biotechnol, 2004).
In the yellow apple, chlorophyll degraded during the ripening process, giving way to carotenoids (Zucoloto et al, J Food Quality, 2017). The main carotenoids contained in the apple peel are, as mentioned, lutein and beta carotene. Lutein is a precious anti-inflammatory substance with a particularly beneficial action for the health of eyesight. In fact, lutein has been shown to even be able to prevent age-related diseases of the macula, the central part of the retina. Not only that, lutein also improves cognitive function, is anticancer and protects the heart (Buscemi et al, Nutrients, 2018). Beta carotene is the most important precursor of vitamin A, is an antioxidant, protects the skin from UV damage, the brain from age-related cognitive impairment, is anticancer and has an anti-arteriosclerotic action (Grune et al, J Nutr , 2010 - Kim, EXCLI J, 2016).