Identifying Food Dyes with TLC
The color of food is an integral part of our culture and enjoyment of life. Who would deny the mouth-watering appeal of a deep-pink strawberry ice cream on a hot summer's day or a golden Thanksgiving turkey garnished with fresh green parsley?
Even early civilizations such as the Romans recognized that people "eat with their eyes" as well as their palates. Saffron and other spices were often used to provide a rich yellow color to various foods. Butter has been colored yellow as far back as the 1300s.
Food color additives are dyes, pigments or substances that impart color when applied to a food, drug, cosmetic, or the human body. The Food and Drug Administration (FDA) is responsible for regulating all color additives used in the United States. All color additives permitted for use in foods are classified as "exempt from certification" or "certifiable". Color additives that are exempt from certification include pigments that are derived from natural sources such as vegetables minerals or animals, and man-made counterparts of natural derivatives. Certifiable color additives are man-made, with each batch being tested by the manufacturer and the FDA. This "approval" process, known as color additive certification, assures the safety, quality, consistency and strength of the color additive. Color additives are available for use in food as either "dyes" or "lakes". Dyes dissolve in water, lakes are the water insoluble form of the dye, are more stable than dyes, and are ideal for coloring products containing fats and oils.
Allura Red AC is a red azo dye that goes by several names including: Allura Red, FD&C Red 40 and disodium 6-hydroxy-5-((2-methoxy-5-methyl-4-sulfophenyl)azo)-2-naphthalene-sulfonate. It is used as a food dye and has the appearance of a dark red powder.
Originally introduced in the United States as a replacement for the use of amaranth as a food coloring, its use has been linked in recent years to increased hyperactivity in children. In Europe, Allura Red AC is not recommended for consumption by children, and although the European Union approves Allura Red AC as a food colorant, the some of the EU countries' local laws ban it entirely, including Denmark, Belgium, France, Switzerland, and Sweden. In Norway, it was banned between 1978 and 2001, a period in which azo dyes were only legally used in alcoholic beverages and some fish products. In the United States, Allura Red AC is approved by the Food and Drug Administration for use in cosmetics, drugs, and food. It is used in some tattoo inks and is used in many products, such as soft drinks, children's medications, and cotton candy.
There are seven certified colors approved for use in food in the United States. Five can be found in M & M ® candies: Blue 1, Blue 2, Red 40, Yellow 5, and Yellow 6.
Chromatography is an important separation technique that depends on differences in both absorption and solubility. One type of chromatography is Thin Layer Chromatography in which a small amount (dot) of the mixture to be separated is placed close to the edge of a piece of chromatography paper. The plate is then set in a developing solution (mobile phase), with the level of the solution below the dots. As the developing solution ascends up the plate by capillary action, the components of the sample are carried along at different rates. To prevent evaporation of the developing solution, this process is carried out in a closed container. Each component of the mixture will move a definite distance on the TLC plate in proportion to the distance that the solvent moves. This ratio,
can be calculated for each component, to aid in identification. Retention factor values are dependent upon the TLC plate, developing solution, and sample size.
Candies, such as M & M's, contain FD&C (Food, Drug, and Cosmetic Act) dyes, sugars, and other organic and inorganic substances in their...