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March 18, 2010

8 Min Read
Naturally Colorful

By R. J. Foster, Contributing Editor

Colors serve myriad crucial roles throughout the food industry. They maintain consistent appearance despite variations in raw materials. Color is the first product characteristic judged by consumers, and is often considered an indication of quality, freshness, even identity. Most Cheddar cheese is orange, athough it comes from white milk. Colas are brownor are they? And who would buy yellow mustard that wasnt yellow? But for todays health-conscious consumers, the right tone isnt enough.

There has never been a time when consumers have been more interested in providing their families with healthy and nutritious food choices, notes Carol Locey, director of product management, colors, Kalsec, Inc., Kalamazoo, MI. For wellness-seeking shoppers, even the perception of artificial colors is a one-way ticket back to the shelf.

Perception is natu-reality

From a regulatory standpoint, there is no such thing as a natural color. FDA defines colorants as certified or exempt from certification. Certified colors like FD&C Red No. 40, Yellow No. 5, Blue No. 1, etc., are prepared synthetically and approved in batches by FDA. Exempt colors are derived from agricultural or biological sources. Despite government guidelines, consumers often consider certified colors as artificial, and exempt colors as natural.

Some exempt colors can be prepared synthetically. Nature-identical products, such as beta-carotene, canthaxathin, apocarotenal, some astaxathin and some lycopene, typically provide the same coloring effects as their natural equivalents. Still, people are happier thinking that the ingredients in their favorite foods came from naturea tree, plant, fruit or seedrather than a laboratory. This is why the general preference for labeling exempt colors is to call them by name: beet juice concentrate (color), or annatto extract (color).

Synthetic products are not without advantage. Certified colors are generally more able to withstand rigorous processing systems, high temperatures and extreme pHs that can have adverse effects on naturally derived colorants. Synthetic products also tend to be more economical and far less likely to affect finished-product flavor.

Many exempt colors are derived from healthy sourcescolorful fruits and vegetablesthe colorants for which are often the healthiest part of the product. Using these compounds to create or enhance the color of a product often provides unique opportunities to market potential nutraceutical benefits.

Deep purple, blue and red

Deeply colored fruits and vegetables owe their purple, blue and red hues to anthocyanins. These water-soluble compounds coloring effect and stability will shift with pH. In acidic conditions, around pH under 3.8, anthocyanins display rich-red tones. As pH increases, color and stability change, resulting in blue colors with reduced stability.

Grape juice and skins from wine production provide a plentiful, economical source for red-purple colors. Purple sweet-potato juice provides superior stability to light for beverage applications. Anthocyanins extracted from red cabbage and black carrots provide good heat stability, while black-carrot juice offers processors good stability across a greater pH range than most anthocyanins. One of the most widely used anthocyanin reds is black carrot, which is an excellent choice to color beverages, confections, fruit preparations and dairy yogurts, says Locey. Other sources of anthocyanins include elderberries, black currants, raspberries, strawberries, cranberries and blueberries.

Members of the flavonoids family, anthocyanins powerful antioxidant activity is believed to help lower the risk of heart disease, improve vitamin C activity, inhibit low-density lipoprotein (LDL) cholesterol oxidation and platelet aggregation, and serve as anti-tumor and anti-inflammatory agents.

Although similar in color to many anthocyanin-rich materials, red beets get their color from betalains. Red and yellow hues are obtained from betacyanins and betaxanthins, respectively. Unlike anthocyanins, betalains color effect is not pH-dependant. Low stability to heat, light and oxidation, especially at pHs outside the range of 3.5 to 5.0, makes beet juice colors best suited to frozen or dried products with a short shelf life. In addition to antioxidant activity, betalains demonstrate antimicrobial and antiviral effects.

Orange you glad

Red, orange and yellow fruits and vegetables provide a family of over 700 compounds called carotenoids. Beta-carotene, perhaps the most-familiar carotenoid, is a powerful colorant able to create colors ranging from yellow to orange to red as concentration increases. And, while only oil-soluble in nature, manufacturers convert beta-carotene into suspensions, emulsions and powders that allow processors to apply beta-carotene to a range of products, from salad dressings to sports drinks, baked goods to butter. In addition to acting as a colorant, beta-carotene is a vitamin A precursor with a provitamin A equivalence of 1,667 IU per mg (pure)a very marketable characteristic, especially for nutritional products.

Lycopene is another oil-soluble carotenoid available in dry, liquid and oleoresin forms suitable for an array of food and beverage applications. Sourced primarily from tomatoes, lycopene is a rich-red colorant that, while not converted to vitamin A, is one of the strongest antioxidants in the carotenoid family.

While stable to heat and acid, these strong antioxidants are themselves susceptible to oxidation.  Protective measures include encapsulation and addition of an antioxidant such as vitamin C.  Care should be taken, though, to ensure that elements added to protect one ingredient do not adversely affect others. 

Annatto seeds have, for ages, been a source of color for clothing, cosmetics and food. Extraction with vegetable oil yields bixin, an oil-soluble carotenoid commonly used to create the familiar yellow colors in butter and processed cheeses. Aqueous alkaline extraction produces norbixin, the water-soluble pigment most notably used to create the distinctive yellow color of Cheddar cheese. Specialized extraction processes yield combinations of both carotenoids for products containing both aqueous and lipid fractions. Annatto colors are stable in alkaline systems, but can precipitate in acidic conditions and fade with prolonged exposure to direct, intense light.

Perhaps better known for flavoring effects, turmeric and paprika can be used to impart bright-yellow and yellow-orange colors, respectively. Carotenoids capsanthin and capsorubin help paprika deliver reddish tones that are stable from pH 2 to 10, but sensitive to light. Turmerics oil-soluble coloring component, curcumin, is available in water-dispersable forms that share paprikas sensitivity to light.

How now brown cow?

Once referred to as burnt sugar color, caramel colors result from controlled thermal treatment of carbohydrates, such as high dextrose corn syrup or sucrose. If you go back 15 years, all caramel colors were considered natural, says Dave Tuescher, technical director, Sethness Products, Lincolnwood, IL.  But with the growing awareness of the many types of caramel colors available and the technology used to create them, there is a growing shift in perspective on naturalness. 

Class I caramel colors are the oldest forms of caramel. They are, but for a possible pH adjustment, made with nothing added. Class II colors are produced with a sulfite, Class III with ammonia, and Class IV with both. These processes broaden caramel-color applications by modifying or enhancing characteristics, including ionic charge, solubility, acid stability, coloring capacity and emulsification effects.

Caramel colors are used throughout the food industry to create colors ranging from yellow to virtually black. They exhibit excellent process tolerance in pHs from 2 to 10, and are unaffected by light. Sulfite-process caramel colors carry a negative charge, making them well-suited to acidic systems, such as soft drinks. Ammonium-process products carry a positive charge that hinders interaction with proteinsa key characteristic in applications such as soy sauce, gravy and beer. Sulfite-ammonium process colors are negatively charged and pH-stable, making them ideal for colas and soft-drink concentrates.

Despite the GRAS and exempt status of all classes of caramel color, some consider only Class I products natural. In turn, there is a growing interest in using Class I colors to replace the others. This is no simple task. Class I colors tend to have weaker colors and higher viscosities, meaning shorter shelf life and higher usage levels to achieve the same coloring as with the other classes, Tuescher explains. He also notes that Class I products tend to have strong flavor. With roughly one-fourth the coloring ability of a Class IV color, Class I colors can pose flavoring issues. Were now developing new Class I colors with much-milder flavor that allow companies to use higher concentrations, he says.

Coloring effect is another potential dilemma when converting classes. Class I caramel colors tend to have more reddish color than the Class IIIs and IVs, explains Tuescher. Today, were developing new Class I caramel colors to deliver hues similar to the Class IIIs and IVs.

Making the switch

Locey estimates that more than 90% of synthetic colors could be replaced with natural colors with very little difference in the appearance of the final product. Yellow 5 (Tartrazine) dye can be replaced with turmeric or carrot. Yellow 6 (Sunset Yellow) dye can be replaced with annatto or paprika. Red 40 (Allura Red) dye can generally be replaced with carmine or anthocyanins, she says.

Converting coloring systems may not be as simple as it sounds, though. The best plan starts with doing your homework. The developer, Locey adds, should consider that there arent off-the-shelf direct replacements for synthetics that will work under all conditions and in all applications.

Consider the product and the parameters that can preclude a given colors usage. Is the product liquid or dry, aqueous or oil-based, acidic or alkaline? Does it possess a delicate flavor character that could be affected by the taste of a naturally sourced colorant? Are there ingredients that could interact adversely with a given type of colorant? Review the processing, handling and storage parameters of the product. Will a natural colorant require additional protection from elements or conditions that could cause oxidation or other loss of effect? And, perhaps most important, consider your audience. Does your target consumer have specific concerns for source, allergenicity, organic or GMO status?

Remember, colors are like clothes. Theres almost always a fit, but one size never fits all.

R. J. Foster is a wordsmith with a B.S. in food science from the University of Wisconsin-Madison and over 15 years of experience in the food industry. He can be reached through his website, wordsmithingbyfoster.com.


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