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August 4, 2008
Color entices us to eat foods, suggesting flavor and freshness. Processing and storage take a toll, so manufacturers often add coloring agents to enhance their offerings. However, several current factors have motivated product designers to rethink their strategies when choosing colorants.
“Artificial,” or certified, colors have long been the first choice: They tend to be more economical; easily produce uniform, intense colors; stand up to heat, light, pH and other factors; and do not add off-flavors. But trends toward more-natural products, ingredient sensitivities and debates over the safety of FD&C certified colors have increased interest in naturally sourced colorants. “The main factor overseas appears to be concerns over the allergenicity or sensitivity to artificial colors, such as led to the recent banning of Red 2G in Europe,” says Jeff Greaves, founder and manager, Food Ingredient Solutions, LLC, Teterboro, NJ. “In the United States, the main driver is the general trend toward natural and organic products, though CSPI just petitioned FDA to ban all artificial colors as unsafe.”
As an added bonus, many of the plant-derived compounds responsible for the natural hues offer some nutritional value, as well.
FDA doesn’t actually recognize “natural colors” unless a product receives its color from the food itself. Berry juice in a berry beverage makes it naturally colored; berry juice in a cherry pie renders it “artificially colored.” FDA lists exempt colorants, many derived from natural plant and animal sources, and these are what are generally termed “natural.” The list also contains inorganic substances, like titanium dioxide and mica.
These colors and their approved uses are listed in Title 21 Code of Federal Regulations Part 73, “Listing of Color Additives Exempt From Certification.” They aren’t all actually “natural” in the strictest sense. Some can be synthetically derived. “Generally, a natural color is one from a natural source and is minimally processed to achieve a stable product in a usable form, avoiding other synthetic ingredients,” says Greaves. “A nature-identical color, such as some beta carotene, is chemically synthesized. For coloring purposes, natural and synthetic beta perform more or less the same, though I have heard they have different nutritional benefits.” He notes other carotenoids, such as canthaxathin, apocarotenal, some astaxathin and some lycopene can also be nature-identical.
Say what you will about artificial colors being “bad for you”—the significant point is many natural colors derive their functionality from “healthy” compounds. “A number contain actives as chromaphores, such as anthocyanins in red cabbage, purple sweet potato, red cabbage, grape juice, elderberry, bilberry, grape skin extract; curcumin in turmeric; and beta carotene in beta and mixed carotenes,” says Greaves. Because of the “linear relationship between color strength and functional ingredient concentration,” nutraceutical companies often use natural colors as functional ingredients, he explains.
One noncertified color qualifies as a bona fide nutrient. Riboflavin, vitamin B2, gives a yellow color. But others are becoming known for beneficial effects.
Carotenoids, which produce red, yellow and orange hues, include carotenes and lycopene, plus the xanthophylls bixin and norbixin (annatto), capsanthin (paprika), lutein (marigold) and zeaxanthin (corn). Carotenes, especially beta carotene, are vitamin A precursors. Bixin and norbixin lack the necessary chemical structures to be vitamin A precursors; however, limited evidence says they may have hyperglycemic effects. Lutein contributes to eye health and may fight macular degeneration. Carotenoids might provide protection against photosensitization and mutations induced by UV light. They help prevent oxidative damage of the lipid components in cell membranes and in circulating blood, and stimulate immune function. However, debate continues whether carotenoids have anticarcinogenicity and antiatherogenic properties, but most of the recent research disproves theories that beta carotene alone is responsible. In fact, two studies (the Alpha-Tocopherol b-Carotene Trial in Finland with 29,133 men who were heavy smokers, and the U.S.-based b-Carotene and Retinol Efficacy Trial with more than 18,000 persons with exposure to asbestos or cigarette smoking) showed an elevated risk of death from lung cancer in the group receiving high-dose beta carotene supplements.
Flavonoids, which include antioxidant anthocyanins, create many of the blues, purples, magentas, reds and oranges. The most-common anthocyanins in foods are perargonidin, cynaidin, delphinidin, peonidian, petunidin and malvidin. Flavonoids’ biological properties can help reduce the risk of disease by acting as antioxidants, extending vitamin C activity, protecting low-density lipoprotein (LDL) cholesterol from oxidation, inhibiting platelet aggregation, and acting as anti-inflammatory and antitumor agents.
With anthocyanins, “the more of the colorant you have present, the more of the ‘active’ compound that is present, as well,” says Byron D. Madkins, director, food and beverage development and applications-color, Chr. Hansen, Inc., Milwaukee. “Thus, the more concentrated one of these colorants, the higher the antioxidant activity.”
Betalaines, in beets, produce reds (betacyanins) and yellows (betaxanthins). These compounds show antiviral and antimicrobial activity in addition to their antioxidant properties. Betalains might function as antioxidants for cell membranes and LDL cholesterol, aiding heart health.
Curcuminoids in turmeric provide a bright-yellow color, as well as effective anti-inflammatory activity. The active phenolic components may inhibit cancer of the stomach, breast, lung and skin, and provide antimutagenic activity.
Part of the difficulty in using many natural colors is their inherent instability. Any antioxidant is susceptible to oxidation. Heat and exposure to light can degrade colors, and changes in pH can shift the resulting color to a different hue. For example, annatto turns pink under acidic conditions, and pHs greater than 7 make turmeric look red and rapidly fade. Metal ions, such as iron, copper, magnesium and aluminum, can catalyze oxidative color loss in carotenoids.
Manufacturers are successfully seeking solutions. Emulsification and encapsulation techniques can increase stability and also make natural colors more user-friendly. Madkins also mentions “ways to take advantage of some of the inherent inter- and intra-chemical interactions at the molecular level to enhance the stability of some fruit and vegetable juices in application.”
The source can also play a role. “We have moved to more stable—naturally acylated—fruit and vegetable sources for anthocyanin colors, such as red cabbage, purple sweet potato, red radish and, to a lesser degree, black carrot, which are considerably more stable than traditional colors from elderberry, grape and hibiscus in most applications, though the latter continues to be used for shade or cost reasons in some applications,” says Greaves.
The same techniques work within the yellow to orange range where, according to a spokesperson from the Color Group of Sensient Technologies, St. Louis, “the best stability is found with natural and synthetic beta carotenes, while turmeric, paprika and annatto might provide the appropriate shade, but lack in end-product stability.”
Madkins explains that, “during the processing of the colorant itself, it is critical that the colorants be extracted utilizing methods that are nondestructive so that all of the attributes are maintained. In the case of anthocyanins, for example, the colorant and the active components are simply expressed and concentrated—if needed—from the source, in order to maintain the integrity of the product.”
A number of technologies may be used to protect the natural color from degradation in the finished consumer product. “The safest method of protecting colors in foods is to shield the product with opaque packaging materials that act like a sunscreen lotion,” says the Sensient spokesperson. “Refrigerated or controlled-temperature distribution helps limit heat degradation of natural colors in finished consumer products.” These techniques often render natural colors as stable as many of the food dyes.
Another hurdle to overcome is the inherent flavors natural sources often bring to the table. “One example of a comparison we can make is that of a typical raw anthocyanin juice blend that contains both the desired natural dyes—approximately 2% to 10% anthocyanins—but also some very objectionable off flavors and off odors that can seriously impact the customer’s finished product,” says the color expert from Sensient. “Natural color concentrates are typically 4 to 10 times more concentrated than the native juice that that color is derived from originally and, generally, have been deodorized and deflavored through additional purification steps. Natural color concentrates, while slightly lower in anthocyanins, provide some of the same health benefits without these undesirable characteristics.”
The future is bright for natural colorants. “As we see a global transition to colors that are more natural, we will also see this part of the available color range grow and be more widely used in foods and beverages,” says Madkins. “With this, consumers will want to know and understand more about natural colors in general. The advantage to this is the fact that many of them, as noted, have already been demonstrated to possess health benefits, aid in metabolism and/or are linked to the prevention of diseases. This increased awareness will encourage even more research into the properties and functionalities of natural colorants.”
“Listing of Color Additives Exempt From Certification” (21 CFR Pt. 73)
73.30: Annatto extract
73.40: Dehydrated beets (beet powder)
73.50: Ultramarine blue
73.95: Beta carotene
73.100: Cochineal extract; carmine
73.125: Sodium copper chlorophyllin
73.140: Toasted partially defatted cooked cottonseed flour
73.160: Ferrous gluconate
73.165: Ferrous lactate
73.169: Grape color extract
73.170: Grape skin extract (enocianina)
73.185: Haematococcus algae meal
73.200: Synthetic iron oxide
73.250: Fruit juice
73.260: Vegetable juice
73.275: Dried algae meal
73.295: Tagetes (Aztec marigold) meal and extract
73.300: Carrot oil
73.315: Corn endosperm oil
73.345: Paprika oleoresin
73.350: Mica-based pearlescent pigments
73.355: Phaffia yeast
73.575: Titanium dioxide
73.585: Tomato lycopene extract; tomato lycopene concentrate
73.615: Turmeric oleoresin
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