Food color plays an historically important role in replacing color lost through processing, thus ensuring the visual appeal and palatability of processed, prepared foods and beverages.

While prepared foods and beverages made from all-natural ingredients, and with only minimal processing, more readily suffer loss of characteristic coloration, even products using more stable colorants are subject to rigorous processing demands, distribution assaults, and long shelf-life requirements.

Although synthetic food colors (FD&C colors) have historically been favored by the industry due to predictable performance and lower cost, in recent years consumers have increasingly demanded the use of natural colorants. But these consumer mandates place new burdens on the natural colorant palette.

Today’s food manufacturers must meet performance and shelf-life requirements that have been strongly influenced by past use of synthetic colorants. In most applications, synthetic colorants are easy to apply, predictable in their behavior, and relatively inexpensive. They support longer product shelf life because of their relative stability under typical packaging and storage conditions.

Color producers are working closely with formulators to assist in transitioning from artificial to natural color sources without compromising appearance, flavor, or stability.
PHOTO COURTESY: GNT USA, Inc. (www.exberry.com)

Natural colorants are much less predictable in their behavior. Due to substantial differences in physical properties such as solubility, pH stability, and compatibility with other food system components, they require formulation approaches that vary with the food system. They also can cost as much as four to 10 times more than synthetic colorants, on a cost-in-use basis. Moreover, in many cases, natural colorants can support only a six- to 12-month shelf life, and they often require changes in packaging, due to light stability issues.

On top of the challenge of getting natural colorants to function in all the required applications while delivering acceptable shelf life and characterizing coloration, other issues follow. Specifically, those challenges include obtaining organic certification, avoiding the pitfalls of legislation (such as California’s Proposition 65), and functionalizing the colorants for various food systems. All the while, the processor must avoid carriers, diluents, and processing aids that run afoul of consumer demand for clean labels.

E SYSTEM

Decades ago, the EU implemented a system of classifying food ingredients and additives for simplified communication on product labels. The system assigned numbers to the various permitted food additives, and these came to be called “E numbers.”

European consumers came to associate E numbers with undesirable “chemicals” in their food, and the move to eliminate E numbers was born, with consumers aggressively driving away acceptance of food ingredients and additives that are viewed as unnatural.

A recent development in the EU is the creation of a category of food colorant called “coloring food” for the highly colored foods (such as red beets or carrots) used to impart color in prepared food products. It can circumvent the need to use an E number on the ingredient statement.

To qualify as a coloring food, a food must adhere to a numerical limit imposed on the selective concentration of the coloring material and must be minimally processed. This supports a claim that the colorant thus produced is not really a colorant but is, instead, a “food that colors.”

Recently developed regulatory guidance permits these ingredients to be used without an accompanying E number designation that would be required for a more traditionally prepared natural colorant, such as red beet juice concentrate. Traditional red beet juice concentrate colorant (E162) does not fit into the coloring foods category because the color in the juice is concentrated beyond the defined limit.

THE MATRIX

While the coloring food system plays well in the EU, it is not as effective a strategy in the US because food colorant regulations require the identification of the color additive according to permitted colorant definitions. There is no definition for “coloring food” in FDA regulations.

Any substance added to food for the (sole) purpose of imparting color must fit the description of a permitted colorant listed in 21 CFR 73, and it must be declared and identified as a colorant (21 CFR 101.22(k)).

On the other hand, most of these “coloring foods” would fit into the regulatory categories of “fruit juice color” or “vegetable juice color.” As such, they would enjoy no distinction over other, more traditionally prepared fruit or vegetable juice colorants.

All these factors have set the bar high for color makers for meeting color stability and functionalization parameters, including fixing to matrix and shelf life. But color makers also are taking the challenge a step further. With advanced technology and intense study and application of color chemistry, they are increasingly able to match the ability of natural colorants to that of artificial colors when it comes to creating subtle nuances of shade.

Synthetic colorants generally deliver consistent performance over a comprehensive range of applications. They produce bright colors and are resistant to many matrix conditions, such as heat, light, and pH. Naturally derived colorants are not so easy to work with. A particular natural colorant might work very well in one application, but will end up working poorly in another unless it is reformulated for compatibility with the new application.

Some natural colorants are stable under varying conditions of heat, light, and pH, while others will be dramatically affected by any or all of these influences. For example, red cabbage juice concentrate provides a bright, stable red color in acidic beverage applications, but in higher pH beverages, the color shifts to blue and fades rapidly.

The differences between synthetic and natural colorants typically have required that compromises be made. If the performance and cost expectations are based on prior experience with synthetic colorants, then there could be a trade-off between the drive for cleaner labels and what can be achieved with natural colorant replacements.

Such compromises can take the form of reductions in shelf life, changes in processing and packaging, adjustments in formulations, and — almost certainly — higher cost-in-use.

NATURAL VS. ARTIFICIAL

Where shelf life is concerned, confectionary products are a good example of the performance of synthetic colorants. Many confectionary items are marketed to younger consumers who favor brighter, more vivid colors. Synthetic colorants, for the most part, deliver on this expectation in products like hard-boiled sweets, gummycandies, and similar products. Shelf-life expectations for these products run to two years or more, and synthetic colorants perform well for that duration.

Natural colorants, by contrast, traditionally have given more muted or pastel colors. Some are sensitive to heat and light, and in general will fade more rapidly over time, especially with exposure to light. Turmeric oleoresin, for example, gives a bright yellow color, making it an excellent replacement in hue for FD&C Yellow #5. Unfortunately, it is highly sensitive to light exposure and fades rapidly under direct sunlight or typical store lighting. Therefore, its use requires opaque packaging for protection from light— yet this hides the vivid color from the consumer.

Advanced technology is allowing a full spectrum of super-stable natural red, orange, and yellow shades that start bright and stay bright in confectionery and other formulations.
PHOTO COURTESY: Lycored, Ltd. (www.lycored.com)

Panned confections, such as hard candy-covered chocolate “lentils,” are another application where shelf life and performance expectations are strongly influenced by an historical use of synthetic colorants. However, natural colorants have been used successfully in panning applications.

Generally, the colors obtained for hard candy coatings are more pastel and less brilliant in appearance, and, in general, they are subject to natural fading, which reduces the product’s viable shelf life with respect to appearance. Advances in natural colorant making, however, have narrowed the gap for these and similar applications.

Carotenoids are a well-known group of chemicals that are produced abundantly in nature and contribute bright yellow, orange, and red colors to fruits and vegetables. Beta-carotene is perhaps the most familiar of these, although more health-conscious consumers might recognize annatto, saffron, paprika, marigold (lutein), zeaxanthin, and astaxanthin. As a class, these carotenoid colorants tend to be oil soluble rather than water soluble, although there are exceptions.

Saffron, for instance, gets its golden yellow-orange color from a-crocin, the di-gentiobiose ester of the carotenoid crocetin. The a-crocin is water soluble, while the crocetin, like beta-carotene, is oil soluble. The solubility characteristics of these compounds have a dramatic effect on their utility.

To be used in beverages, oil-soluble colorants must be emulsified to make them water-dispersible. Water-dispersible colorants in formulations have, in the past, been crafted using high HLB (hydrophyllic-lipophyllic balance) food-grade emulsifiers, such as polysorbate-80. 

Since polysorbate-80 is a synthetic emulsifier, its use is restricted today by consumer demand for clean labels and natural products. Therefore, naturally sourced emulsifying agents must be used. While there are such emulsifying agents from natural sources they are often not as effective, especially in challenging applications like beverage emulsions.

MICRO-MILLING

Turmeric is an example of a natural, oil-soluble colorant which must be emulsified to be used in water-based food formulations. Creating water-dispersible turmeric oleoresin formulations traditionally has relied on the same types of synthetic emulsifiers used with natural lipid-soluble ones. As it becomes increasingly necessary to use natural emulsifiers for the purposes of clean label requirements, colorant technologists have created smart work-arounds. For example, purified turmeric oleoresin can also be rendered water-dispersible using milling technology.

The purified pigment, a powerful nutraceutical antioxidant known as curcumin, can be milled into microparticles using wet-milling techniques. It is processed in water in the presence of a surface-active, food-grade ingredient such as gum arabic. The surface-active compound attaches to the surface of the particles as they are milled, preventing re-agglomeration and allowing the particles to remain stably dispersed in an appropriate liquid medium.

It also is possible to disperse curcumin into a suitable food-grade matrix, extrude it, and then mill the extruded product into fine particles that mimic the functionality of FD&C lakes. Turmeric in these forms is still sensitive to light exposure, but the rate of fading is diminished.

Annatto, high in the super-antioxidant tocotrienol form of vitamin E, is a lipid-soluble natural colorant commonly used in orange cheeses like cheddar, Colby, red Leicester, and others. The addition of this color dates back decades and is said to result from changes in the classical methods of making and selling cheese. Cheddar cheese would normally be an off-white color due to naturally occurring carotenoid colorants that enter the cow’s milk via its diet.

When milk is skimmed to collect fat for production of cream, butter, or cream cheese, the resulting milk contains less color and can appear paler. Cows that are fed hay in the winter also produce whiter milk than cows fed on grass, because hay contains lower levels of carotenoids.

Cheese made from milk will thus naturally vary from light yellow to almost white. Since consumers prefer predictable and consistent color in the foods they eat, it became common practice to add annatto food color to milk during the cheese-making process to standardize the appearance of the cheese across seasons and processing conditions.

While both annatto and beta-carotene can both be used to color dairy products, annatto has a particular advantage. Water-soluble annatto is produced by alkaline extraction of the seeds of the Bixa orellana plant. This process converts the lipid-soluble compound bixin into water-soluble norbixin, which binds more effectively with milk proteins than does beta-carotene. Therefore, in the cheesemaking process, as the cheese curd forms, the annatto colorant is more efficiently trapped in the protein matrix, thus more effectively coloring the curd.

BETTER CARAMELS

Caramel is typically described as a warm and comforting flavor, and caramel color — a nearly $3B market — is one of the most rapidly growing colors called for in confections, pastries, and other formulations. The color typically serves to represent cooking methods —such as grilled, fried, slow-baked, roasted, or long-simmered — and signals a range of flavors from sweet, milky pale caramel to golden butterscotch to deep, umami-rich roasted flavor.

Caramel is a global favorite associated most closely with the comfort cooking found at home. This is true whether the caramel-colored item is a soft English toffee, an Argentinian slow-roasted meat dish, a classic grilled American burger, or a Mexican dulce de leche dessert. Other top regions in demand for more caramel flavor options include North America, Africa, and the Middle East, each with their own distinct taste and flavor profile.

When it was revealed that the manufacturing of caramel colors caused secondary production of the compounds 4-methyl imidazole (4-MeI) and furfuryl alcohol, consumers reacted quickly to decry their use, as the compounds were suspected of increasing risk of certain cancers. Caramel colors containing these compounds were placed on the Proposition 65 list of suspect chemicals.

Caramel color makers rapidly modified their manufacturing methods to lower 4-MeI in their ingredients. Moreover, some caramel colors are created using catalysts and co-reactants, such as sulfites or ammonia. This knocked them out of the running for a clean label. In addition, new FCC monograph requirements that recently went into effect upgraded the specifications and analytical methodologies allowed for describing and verifying a food ingredient’s quality, purity, and identity.

Getting ahead of the game, caramel color scientists developed multiple new lines of caramel colors to meet the requirements of the new rules as well as consumer demand. They’ve created new liquid and powder Class IV, Non-GMO Project-verified offerings. Meanwhile, Class I — a.k.a. “plain” caramel colors that are used for paler brown colors — are able to meet consumer demands for cleaner labels on foods and beverages.

IN THE PINK… AND GOLD

Astaxanthin is a naturally occurring carotenoid found in certain varieties of yeast, algae, fish (salmon, red trout), and shellfish (krill, shrimp, and lobster). It also is produced synthetically. Astaxanthin is what gives flamingos their pink coloration, and it is known to be a powerful antioxidant.

While astaxanthin generally is not permitted as a food color additive in the US, it does find its way into the human diet through the consumption of nutritional supplements containing astaxanthin or from farmed salmon.

Successful application of naturally derived food colorants requires a broad base of understanding about the colorants and their interactions with the food or beverage matrix.
PHOTO COURTESY: Healthy Food Ingredients, LLC/Suntava Inc. (www.suntavapurplecorn.com)

Farmed salmon do not have access to their natural diet, which is the source of astaxanthin that gives their flesh its characteristic hue. Instead, they are fed a diet that contains added astaxanthin, frequently from Phaffia yeast. Otherwise, their flesh would be pale in color and not acceptable as salmon to consumers. In fact, as close cousins of trout, uncolored farmed salmon would be essentially indistinguishable from trout.

Lutein, another lipid-soluble carotenoid that doubles as a good antioxidant, is naturally a yellow to yellow-orange color. It is naturally found in marigold flowers, orange-yellow fruits, and leafy green vegetables, such as spinach or kale.

Lutein is not permitted as a food colorant in the US, but it is permitted as a dietary supplement and as an additive in animal feed. It can be found in eye health supplements, along with zeaxanthin, in products targeting the prevention or slowing of macular degeneration, a leading cause of blindness in adults over age 65.

Lutein also makes its way into the human diet via eggs. Egg yolk obtains its color from naturally occurring colorants like lutein and zeaxanthin in the chicken’s normal diet. As is the case with farmed salmon, factory-raised chickens would have very pale egg yolks. Instead, their feed is fortified with lutein, which makes its way into the yolks of their eggs, giving them their rich gold color.

PAPERWORK

The landscape for prepared foods has been changing rapidly over the past decade, due largely to changes in consumer perception about the healthfulness, nutritional value, safety, and sustainability of prepared foods. Suspicion of food ingredients and additives has growth, leading consumers to question the quality and safety of prepared foods.

As a result, the food industry has been driven toward compliance with more stringent food safety regulations and consumer preferences. This manifests itself in preferences for prepared foods with label declarations like “all natural,” “free from,” and certifications like organic, GMO-free, Non-GMO Project Verified, free range, grass-fed, hormone-free, etc.

Ingredients and additives with “chemical sounding” or hard-to-pronounce names (like carrageenan, xanthan, and titanium dioxide) are avoided with little concern for the actual safety and efficacy of their use. In fact, the first two are completely natural ingredients, the first being a seaweed extract and the second being naturally secreted by bacteria found on certain vegetables.

Legislative efforts like California Proposition 65 create concern among consumers by flagging well-known consumer goods, such as coffee and colas, as containing “known carcinogens.” Against this changing and unstable landscape, the food and beverage industry must constantly adjust and adapt to deliver prepared foods that consumers will accept.

Most natural colorants derived from fruits and vegetables can be certified as non-GMO. However, the carriers and processing aids that may be used in natural colorant formulations, such as modified starches used to improve solubility/dispersibility and maltodextrin as a carrier for powdered colorant formulations, could run afoul of the requirements some certifying agencies have for their programs. The use of food-grade acidulants, alkalis, and buffering salts to control pH might also cause issues in the case of organic certification.

Natural colorants such as beta-carotene are available from several sources, but nature-identical beta-carotene can also be produced synthetically. Other carotenoids, such as lutein, apo-carotenal, and canthaxanthin are also available as nature-identical food additives.

While current labeling regulations do not make a distinction between the natural and the nature-identical versions, organic certification would not be possible for the nature-identical products. Fortunately, during the past several years, color technologists have leapt forward with strong, vivid, and lasting natural colorants suitable for clean-label foods and beverages.