As any kid will tell you, brightly colored foods are more fun to eat than their bland counterparts. But the artificial dyes that give cereals, soda and snack foods their vibrant hues have been hotly debated over safety issues for decades. A study a few years ago concluded that all nine of the artificial dyes approved by the Food and Drug Administration in the US raised "health concerns of varying degrees." In many European countries, the color Yellow #5 has been banned because of its link to hyperactivity and other health concerns, and six other dyes require warning labels in the EU. The need for natural dyes is clear, and a team of researchers at the University of Illinois (UI) is working hard to see if blue and purple corn can pitch in.

Of course, natural dyes do already exist. But, according to Jack Juvik, a geneticist in the crop sciences department at UI, they're not always a smart choice. "Most natural colors come from things like wine skins, red carrots, and beets," he said. "The problem with that is most of the product is wasted in extracting the coloring. It's not good value."

So Juvik and his team have been looking for more economically and environmentally feasible alternatives and, funded by a US$1.4 million infusion from Kraft Foods, they turned their attention to blue and purple corn.

These colorful varieties of corn hold promise because they contain pigments called anthocyanins in their outer layers that can be used to make blue and red dyes. Anthocyanins are a class of flavonoids, a group of plant pigments that have been shown to have anti-inflammatory and antioxidant effects. Anthocyanins have also been found to slow digestion, making them candidates to create foods designed to help diabetics. Because the compounds are located in the outer layer of the kernels, deriving dye from corn could lead to less waste.

"You can process corn in different ways to remove only the outer layer," said Juvik. "The rest can still be fed into the corn supply chain to make ethanol or grits or any of the other products corn is already used for. That outer layer becomes a value-added co-product."

Thus far the dye has been tested in Kraft products including Kool-Aid, Philadelphia cream cheese, Mio water flavoring, and Jello.

To take the dye-making process to the next level, the UI researchers analyzed 400 different lines of colored corn. In addition to measuring the types and concentrations of anthocyanins present, they also wanted to find out if those concentrations remained steady from generation to generation. They found that Peruvian strains of corn showed some of the highest anthocyanin concentrations, and that the compound remained strong from one crop to the next.

"That's good news," said Juvik. "It means we can select for the trait we're interested in without worrying whether it will be expressed in new environments."

According to UI, the next step will be to fuse the Peruvian genes into high-yield corn hybrids created to be farmed in the American Midwest. Of course, that would mean that the dyes derived from the corn would fall under the umbrella of genetically modified organisms (GMO), a category that brings with it its own colorful controversy.

The research has been published in the Journal of Agricultural and Food Chemistry.

Source: University of Illinois