Color Codes: Researcher’s Innovative Work in Natural Food Dyes Gains Recognition

COLUMBUS, Ohio -- It’s not a new idea to use pigments from fruits and vegetables as natural alternatives to synthetic food dyes. But the work being done in Monica Giusti’s lab, focused on compounds called anthocyanins, is making it much more economical to use those natural colorants, and it’s shedding new light on the health benefits of doing so.

For her efforts, Giusti has been recognized as Ohio State University’s 2013 Early Career Innovator of the Year. Giusti is an associate professor of food science and technology in the university’s College of Food, Agricultural, and Environmental Sciences and a scientist with the college’s research arm, the Ohio Agricultural Research and Development Center.

Anthocyanins are the compounds that give color to most red, orange, purple and blue fruits and vegetables, as well as cereal grains and flowers. They are powerful antioxidants, believed to play an important role in the prevention of cancer and other diseases.

But until recently, anthocyanins have been difficult and expensive to isolate into pure forms. To spare her laboratory budget the expense of purchasing purified anthocyanins for research purposes, Giusti developed a new technique to extract the pigments, achieving highly purified anthocyanin blends.

The technique, which was issued a patent early this month, is cost-effective and creates a new market opportunity for expanded research of anthocyanins, Giusti said. Ohio State is partnering with Anthocyantific, LLC, a new venture created to commercialize the product. Giusti is chief scientist for the start-up company.

Giusti’s innovator award comes on the heels of an announcement by Kraft Foods, which revealed it would be replacing artificial dyes with natural ones in its macaroni-and-cheese products marketed to children. The issue is gaining more attention both by consumers and by the scientific community.

“One study showed that artificial food coloring may cause hyperactivity in children, and that is the warning that is now required on food labels in Europe,” Giusti said. “The scientific evidence has not demonstrated convincingly that (synthetic dyes) actually do cause hyperactivity or other negative effects, but regardless, our view is that the use of natural colorants may actually be beneficial, so we are trying to provide alternatives for the food industry and for consumers.”

Giusti’s research began with investigating the red pigments from radishes as a source of a natural red colorant.

“I worked with different varieties and types of radishes for several years, and then I moved into many other commodities. Vegetables in general contain anthocyanins that tend to be more stable to processing, just because of their chemical structure,” she said. “However, anthocyanins in fruits tend to be a bit more bioavailable.

“So, there is plenty of information that we need to investigate. How can we find the best combination?”

Food processors face plenty of challenges in attempting to switch from artificial to natural food colorants, Giusti said.

“The pigments interact with the food,” she said. “They will change depending on the acidity of the food, the sourness of the food, and composition of the food overall -- for example if there are proteins, fats, or other ingredients in that food.

“So, the processor needs to choose the right pigment.”

Processors have several options for natural red dyes, but with blues, the alternatives are limited, Giusti said.

In nature, anthocyanins produce a wide range of colors: Orange, red, purple, violet, and different shades of purple and blue colors, even some black colors, she said.

“However, when we take the plant material, extract the pigments and put them in a solution, all of them typically provide red colors,” Giusti said. “Even, for example, the pigments from blueberries -- you extract them and make juice, you add some lime -- you get red.

“How can the plant make blue with pigments that give us red? We are now focusing a lot of our effort on producing blue colorations.”

The efforts are paying off.

Because of the work in Giusti’s lab, Ohio State University and MARS Chocolate North America, producer of candies including M&Ms, have submitted three patent applications for anthocyanin-based blue colorants. MARS has provided funding for Giusti’s lab for nearly three years.

Health benefits of anthocyanins

Giusti also explores the health aspects of anthocyanins as part of her research, including how even a small doses of anthocyanins’ absorption into plasma can be of benefit to the human body.

“Twenty years ago, no one was paying attention to anthocyanins because absorption in the plasma is very limited, so scientists considered their impact not significant enough to have an effect on health,” she said.

But since then, research has shown that even small doses of anthocyanins going into the plasma can be beneficial.

“They are absorbed quickly and they disappear from the body also rather quickly, but in that interaction, they are potent antioxidants and potent anti-inflammatory agents,” she said.

Giusti’s research primarily focuses on understanding how the chemical structure of anthocyanins relates to their functionality.

There are more than 700 different anthocyanins reported in nature, and though they have a common basic structure, they can become very complex and can range in size from small to very large, she said.

“The different compounds respond slightly differently to the environment -- the conditions in the gastrointestinal tract -- and they provide different functionality in the body,” she said.

One characteristic of anthocyanins is that they don’t necessarily need to get into the bloodstream to have an effect on the body, Giusti said.

In one study with collaborators Purnima Kumar in Ohio State’s College of Dentistry and Mark Failla, from human nutrition in the College of Education and Human Ecology, Giusti is examining the effect of anthocyanins being absorbed directly into tissues in the oral cavity.

In another study with collaborator Josh Bomser, also from human nutrition, she is examining the absorption of anthocyanins in the stomach.

“The stomach has unique characteristics because of its acidic environment,” Giusti said. “Anthocyanins degrade very fast in a neutral pH, but could be much more stable in the acidic pH of the stomach.” The researchers are using a new cell line system to evaluate anthocyanins in the stomach and how the pH of the stomach affects how efficiently they are absorbed.    

Giusti is also co-editor of the new “Anthocyanins in Health and Disease” (CRC Press, 2014), the first book to summarize advances in research of anthocyanins’ role in disease prevention. The other co-editor is one of Giusti’s former students, Taylor C. Wallace, now senior director of Science, Policy and Government Affairs at the National Osteoporosis Foundation.

“This is an early work, because many of the long-term clinical studies on anthocyanins are still underway,” Giusti said.

“Plus, because of the prohibitive prices of anthocyanins in the pure form, a lot of the data on the health benefits of anthocyanins are commodity-based so we don’t know for sure if it’s the anthocyanin causing the benefit, or something else in the product being consumed. We would need to do the studies with the isolated compounds in order to say that.”

Her hope is that such work will blossom with the economical compounds Anthocyantific will be able to provide.

Giusti, who has been with Ohio State since 2004, credits her students for their work in the lab and the research they’ve done.

“Students are the key. They all helped to build up to the place we are now,” she said. She currently advises 10 master’s and doctoral students, as well as an undergraduate.

Sheryl Barringer, interim chair of the Department of Food Science and Technology, said Giusti “is another example of how Ohio State food science professors excel at applying their scientific breakthroughs to solving consumer and industrial needs.”

Honored with Giusti by the university’s Office of Research was:

• Hesham El Gamal, professor of electrical and computer engineering in the College of Engineering, as Innovator of the Year
• Kinshuk Mitra, a fourth-year biomedical engineering major in the College of Engineering as Student Innovator of the Year.

Other faculty members from the College of Food, Agricultural, and Environmental Sciences nominated for Innovator of the Year were:

• Yael Vodovotz, professor of food science and technology, for her work on functional foods, particularly soy bread and soy pretzels.
• Casey Hoy, professor of entomology and Kellogg Endowed Chair in Agroecosystem Management, for his work on http://localfoodsystems.org, an online tool to help connect entrepreneurs rooted in agriculture to strengthen local and regional economies.

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