Interest in natural colorants is increasing, even though challenges exist. For one, natural colorings do not provide the same range of hues as are available with certified coloring. For example, anthocyanin pigments, derived from fruit or vegetables, exhibit a reversible molecular structural change, when the pH of the environment changes. This causes a hue change from red to purple to blue, as the food matrix changes from acidic to basic. This characteristic can create issues for formulators wishing to use anthocyanins in products.

Recently, there has been an industry breakthrough with a new, natural blue coloring that allows developers to use a natural blue color at a lower pH level than conventional anthocyanin colorings. Up until now, there have been some purple-blue hues on the market, but this blue is more of a pure blue at pH values above 5.5. The patented blue color, offered by D.D. Williamson, is derived from red cabbage. “Available in liquid or powder, it was created by a strategic partner of D.D. Williamson, colorMaker,” states Campbell Barnum, global vice president, Branding & Market Development, for D.D. Williamson.

The blue works well in frostings, dry mixes, ice cream and non-acidic confectionery products, but its stability is still greatly dependent on pH and water activity. It is important that the food system have a pH above 5.5 for blue color stability. As the pH drops to below 5.5 and approaches 3.0, the blue hue will change to purple and then to red. It remains a stable blue from pHs of 5.5-7.0, whereas, anthocyanins normally demonstrate a faded and unstable purple hue at a pH of 5.5.

The natural blue coloring also can act as a base for new, natural green products by adding yellow colorings derived from saffron, annatto and/or turmeric. Use levels of the colors depend on the desired color intensity and application. The range is typically 0.05-0.2%. Labeling options for the blue coloring include “color added,” “colored with vegetable juice” or “vegetable juice for color.” Naming the exact color source is also acceptable, such as “colored with red cabbage juice.” Anthocyanins derived from fruit may be labeled “colored with fruit juice” or “fruit juice for color.” Although these anthocyanins are also known for their nutritional antioxidant properties, at the low levels used for color, the antioxidant properties are negligible.

Another coloring option is purple sweet potato, also an anthocyanin that demonstrated impressive stability compared to other red colorings, when used in food products with a pH of 3.5.

When formulating with naturally derived colorings, food developers benefit by considering processing and packaging conditions such as heat, light, pH and shelflife. Often, a single coloring will not work, so a custom blend of non-certified (non-synthetic) coloring is then required to achieve the desired hue and
--Elizabeth Mannie, Contributing Editor 

For more information:
D.D. Williamson • Louisville, Ky.
Jody Renner Nantz •