Naturally occurring blue apples do not exist in nature. Apples typically display a range of colors including various shades of red, green, and yellow. Any blue-colored apples seen are likely the result of artificial coloring, such as candied apples, or are misidentified varieties. While some heirloom varieties might have names that include “blue,” such as the Blue Pearmain, their actual color is typically a deep purple or reddish-purple rather than a true blue.
The Science Behind Apple Colors
The diverse colors of apples stem from specific pigments within their skin. Chlorophyll is the green pigment found in young, unripe apples. As apples mature, the chlorophyll often breaks down, allowing other pigments to become visible. Carotenoids, which are responsible for yellow and orange hues, are present in the apple’s skin and emerge as the green chlorophyll diminishes, giving varieties like Golden Delicious their characteristic color.
Red coloration in apples comes from anthocyanins, a group of water-soluble pigments that accumulate in the fruit’s skin as it ripens. The production of anthocyanins is influenced by genetics, sunlight exposure, and temperature. While anthocyanins can produce red, purple, and even blue colors in various plants depending on pH levels, the specific anthocyanin compounds present in apples typically result in shades of red and purple, not true blue. The genetic makeup of apples simply does not produce the particular blue-hued anthocyanins or other pigments needed for a genuine blue color.
Beyond Natural: The Quest for Blue Apples
The notion of blue apples often arises from artificially colored products, such as dyed candied apples or craft items, or from visual misinterpretations. Very dark apple varieties, like the ‘Black Diamond’ apple cultivated in Tibet, are a deep purple hue that can appear almost black, not genuinely blue, despite potential misperception in certain lighting.
While genetic modification allows for the introduction of blue pigments into apples, no truly blue apple varieties have been developed for commercial sale. Current genetic modification efforts in apples, such as the Arctic apple, have focused on traits like non-browning rather than altering fruit color to blue. This means claims or images of blue apples are not representative of naturally occurring or commercially available fruit.
Naturally Blue Foods
Although apples do not naturally exhibit a blue color, many other foods in nature do. These foods owe their blue coloration to specific types of anthocyanin pigments that differ from those found in apples. Blueberries are a well-known example, containing anthocyanins that give them their distinct blue-purple skin. Other naturally blue foods include blue corn, which is rich in anthocyanins and used in various culinary traditions.
Certain potato varieties, such as the Adirondack Blue potato, also display blue or purplish-blue flesh due to their anthocyanin content. Even some less common examples, like blue carrots and the indigo milk cap mushroom, showcase genuine blue pigments. These naturally blue foods highlight that while blue is a color found in the plant kingdom, the specific biochemical pathways in apples do not lead to this particular hue.