Natural colorants chlorophylls

Phthalocyanines are analogues of the natural pigments chlorophyll and heme. However, unlike these natural pigments, which have extremely poor stabihty, phthalocyanines are probably the most stable of all the colorants ia use today. Substituents can extend the absorption to longer wavelengths, iato the near iafrared, but not to shorter wavelengths, and so their hues are restricted to blue and green. 

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. 

In contrast to the well-established methods for identifying and quantifying naturally occurring chlorophylls, very few reports concern quantitative analysis of chlorophyllin copper complexes in color additives and in foodstuffs. Analytical methods proposed are based on spectral properties, elemental analysis, chromatographic separation, and molecular structure elucidation or a combination of these procedures. 

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. 

Juices extracts (liquorize), spirits (orange, lemon), syrups (black currant), tinctures (ginger), and aromatic waters Mineral pigments (iron oxides), natural colorants, anthocyanins, carotenoids, chlorophylls riboflavine, red beetroot extract, and caramel synthetic organic dyes azo compounds... 

The importance of color to final perceived quality of food products, combined with the labile nature of chlorophyll derivatives, has perpetuated numerous efforts to preserve native green vegetable appearance. Fishenbach... 

Roy et al. (1991) extracted the pigments of green leafy vegetables in methanol-acetone-diethyl ether (1 1 1) the extracts were evaporated, reconstituted in the same solvent, and separated by TLC on silica gel G plates with a chloroform-petroleum ether-toluene-acetone (5 4 4 3) mobile phase. Pheophorbide b, mixed carotenoid, pheophorbide a, chlorophyll b, pheophytin b, chlorophyll a, pheophytin a, and carotene bands were obtained. This method can be used to detect artificial and natural colorants in food products. 

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. 

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 photoprotective role of carotenoids is demonstrated in plant mutants that cannot synthesize essential leaf carotenoids. These mutants are lethal in nature since without carotenoids, chlorophylls degrade, their leaves are white in color, and photosynthesis cannot occur. Generally, the carotenoids are effective for visible light but have no effects in ultraviolet, gamma, or x-radiation. The reactions are listed as follows ... 

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. 

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