Ever since 1971 when a Russian study linked the artificial red dye Red No. 2 to cancer, health conscious consumers have been seeking organic and natural alternatives to use as food coloring. Although the FDA has approved current synthetic food colorings, such as Red 40, for use in food products, and they are generally thought to be safe for consumption in moderate amounts, that has not stopped individuals from turning to vegetable and plant based pigments.
Naturally Occurring Red and Violet Food Pigments
The main food pigments found in the common red beet (Beta vulgaris) are the betalains, water soluble compounds that are one of several flavanoid molecules found within certain plant species. Two categories of betalains exist and each have distinct color and chemical properties. Betacyanins convey a blue-violent to reddish-purple coloring, are a source of antioxidants and are susceptible to color changes depending on their environment. Betaxanthins are yellow or orange, do not function as antioxidants and are relatively stable. Betalains are found exclusively within one plant order, which includes beets, prickly pear cactus, chard and amaranth.
Betanin is a specific betacyanin and the most prominent pigment in the red beet root where it contributes between 75% - 90% of the total visible color. When beet root juice is processed, a concentrated betanin extract is obtained which can later be packaged and marketed as a natural liquid food dye or spray-dried to produce a beet root powder. Organic food coloring can be created if the beet roots themselves were grown organically.
What are the Limitations of Using Beet Root Juice to Color Foods?
Betanin, like other betacyanins, is highly susceptible to changes induced by both pH and temperature. In acidic conditions, at a pH between 3 and 7, betanin maintains its red or magenta hue. However in alkaline, or basic, conditions with a pH greater than 7, the color will rapidly fade to a yellow-brown or tan color. In extremely acidic conditions where the pH is less than 3, betanin will appear bluish or violet.
Natural food dyes derived from beet root juice will also deteriorate when exposed to prolonged high temperatures. How quickly the color fades when heated depends upon the surrounding pH.
What Foods Can be Colored Using a Natural Red Food Dye?
Because of the color change reactions that take place in the presence of alkalinity and heat, natural food color derived from beet root is best used to color foods that will remain cold, such as ice creams, yogurts, frosting, smoothies and cream fillings.
Beet root powder and extract is generally not suitable to use when baking or as a substitute for red food dye in confections such as red velvet cake, as the baking soda used to leaven the product, as well as the temperature needed to bake the cake, will result in a slightly pink but mostly yellowish final product.
Resources
Houghton, J.D & G. A. F Hendry. 1992. Natural Food Colorants. Springer.
Socaciu, S. 2007. Food Colorants: Chemical and Functional Properties. CRC Press.