When we think of food, the colors that often come to mind are red, green, yellow, orange, brown, and white. Blue is a color we rarely associate with what we eat. However, there are some naturally occurring blue foods found in nature. In this article, we will explore some of these blue foods, where they come from, and what causes their unique coloration.
What Causes Blue Color in Foods?
The blue color in naturally occurring foods generally comes from anthocyanin pigments. Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue depending on the pH. They belong to a parent class of molecules called flavonoids synthesized via the phenylpropanoid pathway. Anthocyanins occur in all tissues of higher plants, including leaves, stems, roots, flowers, and fruits.
In plant cells, anthocyanins are localized mainly in the vacuole. The bluer the color, the more acidic the vacuole. Not all anthocyanin-containing plants are blue. Other pigments such as carotenoids may mask or dilute the blue coloration. The amount of anthocyanin also varies in the plants. Higher anthocyanin concentrations generally result in bluer hues.
Some examples of anthocyanin compounds that provide blue hues in plants are:
– Delphinidin gives deep blue/purple coloring
– Petunidin gives blue/purple coloring
– Malvidin provides blue/purple hues
List of Some Naturally Blue Foods
Here are some foods that contain natural blue pigments and appear blue in color:
Blueberries
Blueberries contain anthocyanin pigments throughout their skin and flesh which give them their characteristic blue hue. They contain high levels of malvidin. Wild blueberries tend to be more purple-blue than cultivated blueberries.
Blue potatoes
Certain varieties of potatoes contain enough anthocyanins in their flesh to make it appear blue or purple. Blue potatoes originated in South America and get their color from anthocyanins like delphinidin. The skin may be bluish-purple to deep purple.
Blue corn
Blue corn naturally occurs in the wild and also exists as a cultivated crop. The deep blue/purple kernels derive their color from anthocyanins. Blue corn is nutritionally and antioxidant-rich.
Blue carrots
Anthocyanins in the root give blue carrots their bluish-purple hue. They are sweeter than orange carrots and contain more antioxidants.
Purple Asparagus
Asparagus officinalis grows into green stalks if sunlight is available. With sunlight blocked, it develops anthocyanins and turns purple. The purple pigment is concentrated in the tips. When exposed to air, the purple spears turn green starting from the base.
Blue tomatoes
Bred selectively for higher anthocyanin levels, blue tomatoes have purple skin and sometimes purple flesh. The blue tomatoes tend to be smaller in size than red ones.
Purple cabbage
Some cabbage varieties like purple cabbage contain anthocyanins that give the leaves a blue/purple tint. The pigments are concentrated more in outer leaves. Inner leaves appear greener.
Blue flowers
Certain edible flowers like blue elderberry, blue hibiscus, cornflower, chicory, and hydrangea contain blue pigments. Using them as garnishing or in salads adds sparingly adds blue color.
Blue bananas
A mutant strain discovered in India produces blue bananas. However, these are not naturally occurring and involve genetic mutations.
Blue strawberries
Japanese scientists used genetic engineering to create blue strawberries by modifying anthocyanin biosynthesis. These are not naturally occurring blue foods.
Blue apples
Some crabapple cultivars have purple flesh. However, apples are not naturally blue and these involve cross breeding and not naturally occurring mutants.
Blue sweet potatoes
A selected mutation in regular orange sweet potatoes causes the tuber to accumulate anthocyanins and turn purple/blue. This mutation is rarely found naturally.
Fruits and Vegetables With Blue Skin or Flesh
Here is a table summarizing some fruits and vegetables containing natural blue pigments in either their skin and/or flesh:
| Food | Blue in Skin | Blue in Flesh |
|---|---|---|
| Blueberries | Yes | Yes |
| Blue potatoes | Yes | Yes |
| Blue carrots | Yes | Yes |
| Blue tomatoes | Yes | Sometimes |
| Purple cabbage | Yes | No |
| Purple asparagus | Only tips | Only tips |
| Blue sweet potatoes | Sometimes | Yes |
| Blue bananas | Yes | No |
| Blue apples | No | Sometimes |
| Blue elderberries | Yes | No |
Geographical Distribution of Some Blue Foods
Here is a table summarizing the native distribution of some naturally occurring blue foods:
| Food | Origin |
|---|---|
| Blueberries | North America |
| Blue potatoes | South America |
| Blue corn | Central America |
| Blue carrots | Central Asia, Middle East |
| Purple asparagus | Mediterranean, Europe |
| Blue tomatoes | Andean region, South America |
| Purple cabbage | Europe |
| Blue bananas | India |
| Blue sweet potatoes | Central/South America |
Health Benefits
Many blue/purple fruits and vegetables provide great health benefits. Here are some of the evidence-based health benefits they provide:
– High in antioxidants that reduce oxidative damage and inflammation in the body
– May lower risk of heart disease by reducing LDL cholesterol oxidation
– Potentially anticancer effects by inducing cancer cell death and inhibiting proliferation and metastasis
– Anthocyanins in blue foods may help lower blood pressure
– Blueberries improve insulin sensitivity and may help manage diabetes
– Blue foods provide vitamin C, manganese, fiber and other nutrients
– Anthocyanins may improve cognitive function and protect the aging brain
– Blue corn has been used to make antioxidant-rich blue corn tortillas, chips, muffins etc.
So including blue/purple fruits and veggies into your diet can provide great health boosts. They add nice pops of color and also provide some unique textures and flavors.
Culinary Uses
Naturally blue foods can spice up recipes and provide vibrant colors to dishes. Here are some ways to use such blue foods:
– Make smoothies with blueberries, blue sweet potatoes, blue carrots etc.
– Use blue corn to make tortillas, pancakes, bread or muffins
– Make a salad with purple cabbage, blue potatoes, carrots and dress with blueberries
– Blue potatoes can be roasted, mashed, fried into chips or sliced into wedges
– Pickle or ferment blue carrots and use them in sandwiches, wraps etc.
– Make a stunning purple risotto with blue sweet potatoes or purple cabbage
– Use blue elderberry flowers as edible garnishes for desserts
– Make blue tomato sauce, salsas, bruschetta or gazpacho
– Juice or make jam from blueberries and use as topping or filling in desserts
So get creative with these blue foods in your kitchen and benefit from their unique flavors and colors!
Availability Issues
While vibrantly blue produce is eye catching, many exotic blue foods can be hard to find. Here are some availability issues with such produce:
– Blue potatoes – rare and availability is low outside South America
– Blue corn – less common than regular corn, niche cultivation
– Blue carrots – rare and limited mostly to small farms
– Blue tomatoes – specialty item, not mainstream yet
– Purple asparagus – seasonal and limited harvests
– Blue sweet potatoes – mainly found in Asia, limited export
– Blue bananas – experimental only, not commercially available
– Purple cabbage – available but less common than green cabbage
– Blueberries – widely available but expensive out of season
So access and costs may make cooking with all-blue ingredients challenging. But adding even small amounts of blue foods can provide color and health value.
Conclusion
While blue foods are rare in nature, exciting varieties do exist. These get their color from anthocyanins and provide unique health benefits. Blueberries, blue corn, blue potatoes, purple asparagus and blue carrots are some naturally occurring blue foods. While they may not be easy to source, adding them into your meals can spice up health and flavor. Experimenting with these vibrant ingredients can bring novelty and antioxidants to the dining table. So keep an eye out for these blue beauties at your grocery store or farmers market.