Colorants, food chlorophyll

Hydrolysis of chlorophyll using sodium hydroxide produces the moderately water-soluble sodium salts of chlorophyllin, phytol and methanol (145). The magnesium ia chlorophyllin may be replaced by copper. The sodium copper chlorophyllin salt is heat stable, and is ideal for coloring foods where heat is iavolved, such as ia canning (146). 

A copper complex of chlorophyll in amounts not higher than 1 pg per g of product is used for coloring preserved vegetables, however the complex cannot contain more copper than 200 pg per g (Dz. U., 2003). Non-organic copper compounds were used in the past for food coloration in the 19th Century in England, copper salts were used to color food products and condiments. 

Chlorophyll. Chemically pure chlorophyll is difficult to prepare, since it occurs mixed with other colored substances such as carotenoids. Commercially it is solvent extracted from the dried leaves of various plants such as broccoli or spinach. Chlorophyll is water-iosoluble. It has none of the characteristics of a dye in that it has no aflinity for the usual libers such as cotton or wool. Chlorophyll is properly classified as a pigment tCI Natural Green 3 Cl 75810), As such. It finds use lor coloring soaps, waxes, inks. fats, or nils. Chlorophyll is an ester composed of an acidic pint, chlorophyllin, esterilied by an aliphatic alcohol known as phylol. Hydrolysis of chlorophyll using sodium hydroxide produces the moderately water-soluble sodium salts of chlorophyllin. phytol. and methanol. The magnesium in chlorophyllin may be replaced by copper. The sodium copper chlorophyllin salt is heat-stable, and is ideal for coloring foods where heat is involved, such as in canning. 

See also Annatto Food Colors Carotenoids Chlorophylls Colorants (Foods) and Photosynthesis. 

Steet, J.A. and Tong, C.H. 1996. Degradation kinetics of green color and chlorophylls in peas by colorimetry and HPLC. J. Food Sci. 61, 924-931. 

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. 

Carotenoids are also present in animal products such as eggs, lobsters, greyflsh, and various types of hsh. In higher plants, they occur in photosynthetic tissues and choloroplasts where their color is masked by that of the more predominant green chlorophyll. The best known are P-carotene and lycopene but others are also used as food colorants a-carotene, y-carotene, bixin, norbixin, capsanthin, lycopene, and P-apo-8 -carotenal, the ethyl ester of P-apo-8-carotenic acid. These are Upid-soluble compounds, but the chemical industry manufactures water-dispersible preparations by formulating coUoid suspensions by emulsifying the carotenoids or by dispersing them in appropriate colloids. ... 

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. ... 

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... 

Lipid-soluble food grade copper chlorophyll is manufactured similarly by extraction of adequate plant material, followed by replacement of magnesium by copper, and purihcation steps to remove carotenoids, waxes, sterols, oils, and other minor components that are co-extracted. Commercial copper chlorophylls may vary physically, ranging from viscous resins to fluid dilutions in edible oils as well as granulated forms and emulsions standardized with edible vegetable oil. Colors may vary... 

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. 

Weemaes, C.A. et al., Kinetics of chlorophyll degradation and color loss in heated broccoli juice, J. Agric. Food Chem., 47, 2404, 1999. 

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