New Generation of Natural Colors For Food, Beverages

INDIANAPOLISMention purple sweet potatoes, black carrots or purple carrots, and people think of dining on heirloom or boutique veggies, but those vegetables among others have quietly become sources of a new generation of natural food colorings that are replacing traditional synthetic colors, according to new research presented at the National Meeting & Exposition of the American Chemical Society (ACS).

Speakers described how natural colors used centuries ago are making a resurgence in response to consumer preferences, manufacturers' needs and possible health benefits.

"In addition to adding eye appeal to foods and beverages, natural colorings add natural plant-based antioxidant compounds that may have a beneficial effect on health," said Stephen T. Talcott, an associate professor at Texas A&M University.

He said one major change is the appearance of root crops like black carrots and purple sweet potatoes (PSPs), which are grown specifically for the natural colors industry. They have become primary agricultural products, compared to fruits, such as grapes, which are grown for other purposes and used as secondary or byproduct-based colors.

Talcott focused on the range of colorsfrom light pink to rose, red and deep purplethat can be obtained from PSPs. Available commercially in the United States since 2006, PSPs contain the same anthocyanin pigments found in black cherries, and taste like regular sweet potatoes when baked, used for french fries or prepared in other ways.

PSP anthocyanins have proven to be among the best for food and beverage coloring, he said, citing fruit drinks, vitamin waters, ice cream and yogurt. They are stable, and do not break down easily like many natural colors; have superior coloring properties; and have a relatively neutral taste (in contrast to the slightly earthy, bitter taste from grape-based colorings). They are also more sustainable and more easily produced than both traditional synthetic red food colorings and the "carmine" reds extracted from cochineal insectsit takes about 2,500 bugs, which feed on a certain type of cactus native to South America and Mexico, to produce 1 ounce of the cochineal extract used in ice creams, yogurts, candy, beverages and other foods.

However, PSP anthocyanins are difficult to extract. Talcott reported on development of a new process that extracts larger amounts of pigment from PSPs. Byproducts of the process include starch and fiber, which could be used as animal feed, in various food applications or as a raw material for biofuel production.

Such processes could encourage development of a domestic natural food coloring industry, with agriculture spreads devoted to growing foods for the coloring industry. The U.S. currently imports much of its natural food coloring, and the small number of PSPs grown domestically are sold mainly as fresh produce.