Natural chlorophyll food colorants

Both chlorophylls and carotenoids occur in all green leaves, but their color is masked by chlorophyll in photosynthetic tissues. When the chlorophylls break down as leaves senesce (mature), the yellow and orange carotenoids persist and the leaves turn yellow. Carotenoids are responsible for the colors of familiar animals such as lobsters, flamingos, and fish. Often people are unaware of the chemical nature of food colorants. ... 

In addition to the U.S. certified coal-tar colorants, some noncertified naturally occurring plant and animal colorants, such as alkanet, annatto [1393-63-17, carotene [36-884] C qH, chlorophyll [1406-65-17, cochineal [1260-17-9] saffron [138-55-6] and henna [83-72-7], can be used in cosmetics. In the United States, however, natural food colors, such as beet extract or powder, turmeric, and saffron, are not allowed as cosmetic colorants. 

The aim of this chapter is to provide a concise synopsis of the factors that promote degradation during post-harvest handling, processing, and storage, and the strategies to preserve the green color of the most commonly consumed chlorophyU-rich foods. Some considerations about the production and characteristics of natural and semisynthetic chlorophyll derivatives for use as food colorants are also presented. 

Commercially produced metal-substituted chlorophylls such as copper chlorophylls and copper chlorophyllins that can be obtained by chemical modification of natural chlorophylls have better stability, solubility, and tinctorial strength, but they cannot be considered natural food colorants and will be discussed later. 

Although chlorophyll and chlorophyllin colorants seem to be easily obtained, in practice their production as natural food colorants is rather difficult. The sensitivity of chlorophylls to certain enzymes, heat, and low pH, and their low tinctorial strength greatly limit their manufacture and application as food additives, principally when the pigments are isolated from the protective environment of the chloroplasts. The well-known instability of chlorophylls prompted extensive research for developing... 

Hendry, G.A., Chlorophylls, in Natural Food Colorants Science and Technology, Lauro, G.J. and Francis, F.J., Eds., Marcel Dekker, New York, 2000, 344. 

Hendry, G.A.F., Chlorophylls and chlorophyll derivatives, in Natural Food Colorants, 2nd Ed., Hendry, G.A.F. and J.D. Houghton, Eds., Blackie, Glasgow, 1996, 131. Singh, V., ed., Seabuckthom, A Multipurpose Wonder Plant, Vol. I, Indus International, India, 2005. 

The chlorophylls are a group of naturally occurring pigments produced in all photosynthetic plants including algae and some bacteria. Hendry24 estimated annual production at about 1,100,000,000 tons with about 75% being produced in aquatic, primarily marine, environments. Obviously as a source of raw material for food colorants, chlorophylls present no problem with supply. 

HENDRY, G. A. F. Chlorophylls. Chap 10 in Natural Food Colorants. Edit. G. J. Lauro and F. J. Francis. Marcel Dekker, New York, 2000, pp. 227-36. 

Most stains consist of colored substances of natural origin belonging to the polyphenol, carotenoid, or chlorophyll class. Artificial food colorants, cosmetic ingredients, and decorative dyes complete the stain portfolio. Very often stains are complex mixtures of spilled food preparations or beverages. Combined with oils, fats, or other organic material, such as proteins, starch, or waxes, the properties of stains are quite different from those of isolated dyes. Only a small proportion of all stains is fixed on surfaces by physical adhesion. On fibers, in particular, strong interactions often result in covalent bond formation. This process is more important on cotton than on synthetic fabrics. 

Furthermore, the carotenoid pigments, either in isolation or jointly with other natural pigments such as chlorophylls and anthocyanins, are responsible for food color. Color is the first characteristic the consumer perceives of a food, and confers expectations of quality and flavor. Food quality is judged firstly on color, and the consumer will reject foods with an external color other than that established as correct. The food industry, knowing well this natural relation of color-quality (and vice versa), tries to adjust the industrial processes of transformation and preparafion of foods to preserve the integrity of the compounds responsible for an acceptable color. This is not always possible, and it is normal practice to add coloring matter to enhance, homogenize, or even modify color to make the food more attractive to the consumer. 

Coloring of food can be accomplished by synthetic or natural dyes. The laws pertaining to food colorings are different from country to country. However, natural products (- dyes, natural) are normally accepted. Examples are cochineal, chlorophyll, carotenes, bixin and betanin as well as - caramel color. 

Humphrey, A.M., Chlorophyll as a color and functional ingredient interaction of natural colors 12th World Congress of Food Science and Technology. J. Food Set, 69, c422, 2004. 

Finally, passing mention must be made of the two most important organic pigments in our world, both natural products. These are chlorophyll and haemoglobin, which are absolutely vital in the strict meaning of the word, but only chlorophyll has found a commercial use as a colorant in food preparation. 

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