Eating the Rainbow: The Colorful Chemistry of What We Eat
- Piece of Cake Staff
- Jul 4
- 7 min read
Written by Lindsay Grohs
Have you ever wondered what makes your blueberries blue? Or your carrots orange? There’s science behind those colors—chemistry that not only makes our food look beautiful but also reveals clues about its nutrients, freshness, and flavor. Every color on your plate has a unique story, from the deep reds of your tomatoes to the bright yellow of your corn on the cob. Food is more than just eye candy—it's literally edible science. In this article, we will explore the rainbow behind your plate: what causes those colors, what they signify, and how different temperatures can change them. Get ready to uncover the colorful secrets of your food!
The Color Wheel of Food
We’ve already established that pigments affect the color of your food. But what pigments produce what colors? Lucky for you, I’ve got a guide that will break this down for you. Let’s get into it!
Red
Red colors are produced from anthocyanins, carotenoids (specifically lycopene), betalains (specifically betacyanins), and carminic acid. I know those names might sound intimidating—or like pure science gibberish—but they’re actually pretty simple once you break them down. Anthocyanins will produce red hues in more acidic environments. Their color range is pH-dependent—appearing red in more acidic conditions (like when combined with lemon juice and vinegar), purple in neutral ones (such as pure water), and blue in alkaline settings (such as when baking soda or mineral-rich water is present). This means the same food can shift color depending on how it’s cooked or combined. Some common sources of anthocyanins include red cabbage, berries (strawberries, raspberries, and cherries), and red grapes. Carotenoids, specifically lycopene, are responsible for the bright red to orange colors found in foods such as tomatoes, red peppers, pink grapefruit, and saffron. Unlike anthocyanins, carotenoids are fat-soluble and heat-stable, meaning they retain their color well during cooking and are better absorbed when eaten with a source of fat. Lycopene, a type of carotenoid, is especially known for its antioxidant properties, giving certain foods their deep, vibrant red hues.
Betalains, specifically betacyanins, provide a deep red, magenta color to foods such as beets and dragon fruit. Betalains are water-soluble, making them more stable in slightly acidic conditions, allowing them to hold their color in these conditions and fade in more neutral or alkaline environments. Lastly, we have carminic acid. Carminic acid is the key pigment responsible for bright red to deep pink colors. It is derived from cochineal insects—the natural source for carmine dye. Unlike many plant-based pigments, carminic acid is water-soluble and remarkably stable when exposed to heat, light, and oxygen, making it ideal for use in a variety of products. It’s commonly found in alcoholic beverages, processed meats, and candy. However, since it comes from insects, it may not be suitable for vegan or vegetarian diets.
Orange
Orange hues are mainly derived from carotenoids. Carotenoids—especially beta-carotene, alpha-carotene, and beta-cryptoxanthin—are found in foods like carrots, sweet potatoes, pumpkin, mangoes, and orange bell peppers. They are the most common and reliable sources of orange color in nature. Pretty cool! They are also both fat- and heat-soluble, meaning they retain their color during cooking and don’t shift in response to changes in pH.
Yellow
Yellow colors originate from three primary pigment groups: riboflavin, carotenoid, and betaxanthin (a subgroup of betalains). Riboflavin, also known as vitamin B2, is commonly found in foods such as milk, eggs, yeast, and green vegetables. Its light sensitivity and water solubility make it easily degradable in the sunlight and during prolonged exposure to heat or water, reducing both its nutrition and color intensity. Riboflavin is also commonly used as a natural food colorant (E101) in foods such as cereals, energy drinks, and baked goods. The next yellow color pigment contender is one we’ve heard a few times now—carotenoid. Carotenoids—especially lutein, zeaxanthin, and beta-cryptoxanthin—are found in corn, squash, leafy green vegetables, and yellow peppers. Lastly, betaxanthins are found in foods such as golden beets, yellow cactus fruit, and some pitayas. They are known for their water solubility and heat sensitivity. While they usually keep their color when exposed to water, they can degrade or shift in color when exposed to high temperatures or environments that are too acidic or alkaline, making betaxanthins best preserved in raw form.
Green
Green hues are primarily derived from chlorophylls and carotenoids. Chlorophyll, the most dominant green pigment in nature, is responsible for the color of leafy greens such as spinach, kale, broccoli, and parsley. This pigment is fat-soluble and sensitive to heat, light, and changes in pH, causing it to shift in color to a more dull green when exposed to heat or acidic environments. This is why green vegetables are often blanched quickly or cooked with great care to preserve their vibrant hue and nutrients. Carotenoids contribute to green hues by mixing with chlorophyll to create layered, complex greens such as peas and green beans.
Blue
Blue colors stem from anthocyanins (specifically delphinidin) and phycocyanin. Delphinidin is the compound responsible for the blue and purple shades found in foods like blueberries, black currants, and grapes. Like other anthocyanins, it is highly pH-dependent—its blue color is stronger in alkaline conditions and more faded in acidic ones. Meanwhile, phycocyanin, a pigment found in blue-green algae such as spirulina, provides a bright, stable blue color popular as both a natural food coloring and supplement.
Purple
Purple shades arise from anthocyanins, specifically the compounds peonidin, petunidin, and malvidin. Both peonidin and petunidin are responsible for deeper shades of purple, appearing in foods such as plums and grapes. Malvidin is also responsible for violet-like and reddish hues appearing in various grapes and berries. Like other anthocyanins, the exact color can shift depending on pH factors. More acidic conditions make the colors appear redder, and more alkaline environments enhance their purple tones.
Pink
Pink hues originate from pigments such as betanin and curcumin. Betanin, a betalain pigment, is commonly found in beetroot. It’s suitable for frozen and dried foods due to its relative stability under those conditions. Curcumin, derived from turmeric, can also contribute to warm yellow-orange tones that sometimes appear as soft pink hues when blended with other pigments.
Black
Black hues come from two main pigments: melanin and vegetable carbon (activated charcoal). Melanin is found in foods like black garlic, black rice, and black beans. Maillard reactions, which occur when proteins and sugars react under heat, and enzymatic browning, which happens when proteins react with oxygen, both help produce these complex brown and black pigments and flavors in foods. Vegetable carbon, also known as activated charcoal, is an ingredient derived from charred plant materials and used as a natural black coloring in confectionery products, black ice cream, and black breads.
Artificial Colors: The Dark Side of Bright Food
Now that you know some of the science behind what naturally colors your foods, it’s worth discussing the role of artificial colors in our diets. Natural pigments offer nutritional benefits such as antioxidants and vitamins, but what about artificial pigments? Artificial colors are often used for consistency, brightness, product promotion, and cost-effectiveness. Based on this information, the question then becomes, are they truly safe? And are they truly necessary?
Artificial colors provide vibrant, uniform hues that make food visually appealing. These bright, eye-catching colors are linked to increased appetite and enhanced consumer interest, making these foods a powerful driving force in the food market. They are cheaper to produce, making it more cost-effective for companies producing on a larger scale. These dyes also have a longer shelf life compared to natural pigments due to their stability under heat, light, and pH conditions. Artificial colors also have the advantage of offering a broader palette beyond the limitations of natural pigments, allowing greater creativity in food design. While all of this may sound enticing, there are many drawbacks to artificial colors. For starters, there are many health concerns related to artificial dyes, such as hyperactivity, allergic reactions, and potential cancer-causing agents. Secondly, there are no nutritional benefits, as they are “petroleum-derived chemicals that do not occur in nature” (Bailey, 2024). They lack the antioxidants, vitamins, and nutrients that natural pigments offer foods. Additionally, the production of artificial dyes can cause negative impacts on the environment, as they are “often released untreated into waterways or used directly for irrigation, causing detrimental impacts on human health and ecosystems” (Bailey, 2024). When this happens, it causes further damage to the receiving bodies of water as it hinders “the degree of visible light reaching the photic ozone” and contains properties that are harmful to plants, animals, and humans (Lin et al., 2023).
It’s important to keep all of these factors in mind when buying and choosing foods. Understanding the differences, as well as the pros and cons, between natural and artificial colors empowers you to make more informed, health-conscious, environmentally mindful decisions about what enters your body.
Color isn’t just something we see—it’s something we eat, experience, and respond to. The pigments in our foods hold value, tell stories, and explain the chemistry behind our plates. Understanding the differences between natural and artificial colors allows you to make more informed decisions about the foods you are eating. So next time you are shopping at the grocery store, take a second to ask yourself: What’s behind that color? Because, after all, the more we understand the colors on our plate, the more connected we become to the food we are eating and the choices we are making.
Thumbnail Credit:
Citations:
Comments