Purple Sweet Potatoes as Coloring Agents
Purple sweet potatoes, black carrots or purple carrots have replacement potential for traditional synthetic colors and colors derived from beetles.
Stephen T. Talcott, Ph.D., Texas A&M University, said that the natural colors industry for foods and beverages is gaining in value as U.S. and international companies move toward sustainable and affordable crop alternatives to synthetic red colors and red colors derived from insects.
He said that 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.
Talcott said that 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. He asserted that 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 colors -- from light pink to rose, red and deep purple -- that can be obtained through use of the pigments in PSPs.
He observed that, though available commercially in the U.S. since 2006, it still is hard to find in stores; PSPs have the same anthocyanin pigments found in black cherries. Baked, used for french fries or prepared in other ways, PSPs taste like regular sweet potatoes.
Talcott said that PSP anthocyanins have proven to be among the best for food and beverage coloring, citing fruit drinks, vitamin waters, ice cream and yogurt.
They are stable, for instance, and do not break down easily; have superior coloring properties; and have a relatively neutral taste (in contrast to the slightly earthy, bitter taste from grape-based colorings). The pigments, however, are difficult to extract.
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