A visit to the farmers market — especially right now — will likely yield a rainbow-colored assortment of fruits and veggies. Come August, the tomatoes alone will span the spectrum from red to purple with nearly everyt shade in between. And yet, if you want something blue, your options are much more limited. Of course there are blueberries, but the dearth of blue makes us wonder (and maybe you've been wondering, too): Why is it that so few foods are blue?
What Does It Mean to Be Blue?
Before we get to the question of why, it helps to understand what we mean by "blue." The main family of pigments responsible for the bluish hue of blueberries, blue potatoes, and blue corn, are called anthocyanins. They're the same natural colorants that cause grapes and eggplants to be purple, and cherries and raspberries to be red.
Exactly which color anthocyanins create depends on their quantity and the pH inside the plant tissue, says Chris Gunter, a professor of horticultural science at North Carolina State University. The pigment they present can change throughout a plant's seasonal cycles, as a fruit ripens, say.
So, are blue foods really blue? Maybe not. In 2013, a short segment on the Food Network showed a device called a spectrophotometer used to detect the real colors of foods we consider blue. The device bounces white light off a food and then picks up the wavelength of the color reflected back. As it turns out, the foods we assume to be blue are far from true blue; instead, they’re more purple.
Which brings us back to our original question.
Why Are So Few Foods Blue?
There’s an evolutionary reason why blue may be the odd man out, says Gunter. It has to do with the fact that blue light is among the highest energy wavelengths in the visible light spectrum. Some posit that, in order to grow more efficiently, plants absorb that light and use the energy, where they might otherwise be reflecting the light (and we would see blue).
Another possible explanation: Blue foods aren't particularly appealing to humans (or animals for that matter). “Almost universally, it is difficult to get a consumer to try a blue-colored food,” Gary Blumenthal, a representative from International Food Strategies, told colormatters.com. In fact, the color blue actively suppresses our appetites (and, to curb overeating, some recommend putting a blue lightbulb in the refrigerator).
The Future of Blue Foods
But while early humans might have found themselves selecting for non-blue varieties, Gunter predicts we'll be seeing more blue- and violet-hued foods in the near future. Because they're full of antioxidants, which have been associated with prevention of diseases like cancers, heart disease, and Alzheimer's, health-conscious eaters are starting to pay more attention to them. As demand increases, Gunter says, blueish varieties of vegetables like cabbage, carrots, celery, and kohlrabi will be easier to find.
Are you a blue-food fan? Share your thoughts with us in the comments!