Cherries (Prunus genus) are known for their sweet-tart flavor and vibrant color palette, ranging from yellow to deep red. The existence of deep indigo shades in other berries often leads people to wonder if a true blue cherry exists. This article addresses the question of blue cherries by examining the biological mechanisms that control fruit color.
The Definitive Answer About Blue Cherries
The definitive answer is that true, naturally blue cherries (Prunus avium or Prunus cerasus) do not exist. Despite centuries of cultivation and selective breeding, which have yielded cherries in shades ranging from bright yellow to nearly black, a stable blue hue remains genetically absent from the species. The closest natural color varieties are the darkest purple or black cherries, which can appear to have a bluish cast under certain lighting. This lack of a true blue is a limitation imposed by the specific pigments the cherry plant is capable of producing.
The Biology of Cherry Color
Cherry color is determined by water-soluble pigments called anthocyanins, stored within the fruit’s skin cells. These pigments are responsible for the spectrum of red, purple, and black colors found in cherries. The exact shade expressed by anthocyanins depends heavily on the acidity level, or pH, of the fruit’s cellular sap.
Anthocyanins naturally express red, pink, or purple colors when the environment is acidic, which is the natural condition inside the cherry fruit. Sweet cherries are mildly acidic (pH 3.7 to 4.2), and sour cherries are even more acidic (pH 3.1 to 3.6). Achieving a true blue color requires the anthocyanin molecule to be in a high-pH, or alkaline, environment, often above pH 7.0.
Because cherry fruit is inherently acidic, its anthocyanins are chemically locked into the red and purple color range. Although some anthocyanins, like peonidin, can exhibit a deep blue hue at pH 8 or higher, the cherry tree lacks the genetic ability to produce this specific pigment and maintain the necessary alkaline conditions. The combination of the cherry’s low pH and its specific pigment profile prevents the expression of a stable, true blue color.
Common Lookalikes and Misconceptions
The belief in blue cherries often stems from encountering other blue, cherry-sized fruits or misleading images online. Common blue fruits like blueberries and huckleberries contain different pigment compounds than cherries. Their blue color is often the result of a waxy coating that scatters light, shifting the color expression toward blue even at a lower pH.
Another source of confusion is the fruit of the Decaisnea fargesii, known as the Blue Sausage Fruit or Dead Man’s Fingers. This plant produces elongated, metallic-blue pods that are visually striking but unlike any true cherry. Viral images of bright blue cherries are typically the result of digital manipulation or artificial food dyes, which are synthetic processes, not reflections of the natural world.