Researcher Finds Color Solutions in Nature

The color of a food is one way we decide what’s safe and attractive to eat. Yet, historically, color has been perceived as less important than other product attributes, according to M. Monica Giusti, associate chair and distinguished professor with The Ohio State University Department of Food Science and Technology.

That’s changing. In many countries around the world, questions about the safety of synthetic food dyes are triggering new rules and regulations around their use, which has left some food companies scrambling for alternatives. “I’ve seen many, many companies go into panic mode,” Giusti says.

And that’s where her research comes into play. Giusti is studying a new class of anthocyanins with the potential to function as natural colors in food and beverage products.

Replacing artificial colors isn’t simple—for reasons that may involve the entire supply chain, Giusti explains. “There are so many different layers of potential complications,” she says.

Natural options are usually less stable than synthetics, which means they have a shorter shelf life. The amount of color required to get the same effect might be different, and that could necessitate changes in formulation and production processes. If more color is required, that means more storage space is needed, for example. Natural colorants may need refrigeration where their synthetic counterparts do not.

Then there’s the fact that a colorant that works well in one formulation might not work in another. “If you had 10 products using Red Dye No. 3, you may not be able to replace it with one natural alternative,” Giusti says.

Adding to the difficulty of swapping color sources is the complexity of the food matrix. Adjusting even a single ingredient in a formulation could require adjusting all the ingredients, Giusti notes. “Sometimes even changing the source of one ingredient can cause changes in the way that the whole food works or the interaction of the ingredients works,” she says.

Giusti began researching natural alternatives to synthetic colors during her master’s degree studies in the 1990s, and she received funding from a food company looking for substitutes. But making the switch was so difficult that companies went back to synthetics, she says. There was also resistance from consumers when the colors of existing products changed. And while consumers want quality, they’re not always willing to pay a higher price for it.

“If you have to go through a lot more work, then you may need to increase the price of the product,” says Giusti. “The last thing consumers want right now is food going higher in price.”

Promising Alternatives

Giusti has been studying one natural source of color, anthocyanins, for 30 years. Apart from adding color, anthocyanins contain antioxidants and anti-inflammatory agents, which are linked to health benefits. So far, more than 700 anthocyanins have been found in plants.

But anthocyanins can be tricky: Their chemistry is complex, and they change depending on the environment in which their source plants are grown and in which they’re stored. They are also sensitive to light and temperature changes. And then there’s that complex food matrix.

“We have [done] decades of research just to better understand how the chemical structure of the anthocyanin can affect their interaction with that food matrix,” Giusti says. Some anthocyanins are already used in food applications. Black carrots, red cabbage, and red radish all provide colors ranging from purples to reds. Red radish, for example, produces a bright red that’s very similar to Red Dye No. 40, which is one of the most widely used color additives.

One of Giusti’s current research projects examines a new class of colorants called pyroanthocyanins, which have the potential to solve many of the issues that occur when other natural colors are used in formulations. One part of this research, with funding provided by the U.S. Department of Agriculture, is investigating the use of agricultural byproducts as an efficient source of pyroanthocyanins, which could provide a sustainable, cost-effective, and accessible supply.

“Pyroanthocyanins remain colored through all the different pHs,” Giusti says. “They change slightly, but they don’t lose the color like the anthocyanins typically do,” she continues. “And they produce beautiful colors from orange to red to violet.”

Her lab is also working to create an anthocyanin-derived blue that maintains color at low pH levels. “The blue colorant is a very exciting project because currently there are no really good alternatives for the synthetic blue colors for acidic applications,” Giusti says.

Even with the many natural sources that can be used to color foods, scaling up for commercial production remains a hurdle. Producing large and consistent quantities of colorants requires controlled agricultural production.

Ultimately, Giusti expects to see more limited use of synthetic colors, driven by consumer demand, and the work she and her team are doing will, she hopes, lead to more viable natural color options for product formulators.ft