Nature-identical colorants

The present market for food colorants is estimated at 1 bilhon USD, while the natural food colorant market is only one-third of it. Synthetic colorants have achieved better results than natural or nature-identical colorants until now because of greater stabihty and higher ratios of coloring yield. 

According to Newsome (1990) only nine synthetic colors are currently approved for food use and 21 nature-identical colors are exempt from certification. The approved FD C colors are listed in Exhibit 11-2. Citrus red no. 2 is only permitted for external use on oranges, with a maximum level of 2 ppm on the weight of the whole orange. Its use is not permitted on oranges destined for processing. 

The natural or nature-identical colors are less stable than the synthetic ones, more variable, and more likely to introduce undesirable flavors. The major categories of natural food colors and their sources are listed in Table 11-5. 

Certain colorants are not required by the FD C Act to be certified by fhe FDA before use (Table 3). These include natural organic and inorganic colorants and certain synthetically produced so-called, nature-identical colors such as p-carotene. Although these colors are exempt from certification, they are still regulated by the FDA regarding their specifications, uses, and restrictions. 

For most natural and nature-identical colors, the storage conditions are more stringent and a manufacturer s recommendations for a particular coloring agent should be followed. 

The organic dyes, natural colors, and nature-identical colors present a greater hazard and appropriate precautions should accordingly be taken. 

Much of the detailed chemistry to understand food colorants comes from the textile and paint industry. Otterstatter (1999) and Christie (2001) state that colorants can be classified according to their chemical composition and method of application. The latter method of classification is detailed in The Colour Index (1988) and outlined by Otterstatter (1999), but is of limited use in our study of food colorants. In classification of food colorants two approaches are commonly taken, firstly, that based on the origin of the colorant and secondly, that based on chemical stractme. In relation to origin this refers to whether a food colorant is natural, natme-identical or synthetic (Dalzell, 1997). Probably the best definition of a natural colorant is one which is synthesised, accumulated or excreted from a living cell (Dalzell, 1997). Nature-identical colorants are those produced by a chemical synthesis to match the chemical stmctme of colorants found in nature. Synthetic colorants are those which are chemically synthesised and do not occur in nature. Proudlove (1994) considers that we should not use the term synthetic, but instead split food colorants into those naturally present in foods and those added to foods. This, however, also... 

Hair dyes must meet a number of conditions related to their end use. Color can be assessed by colorimetry [49], The limits of precision are set by the substrate on which the measurement is performed. Studies on test subjects are difficult because of the uneven natural hair color and the background color of the scalp. Tresses are hard to prepare at a constant quality level. Measurements on wool cloth give reproducible results, but for oxidation dyes the shades are not identical to those produced on hair. Colorimetric methods are therefore useful only for comparative measurements on the same object, for example, in lightfastness tests. Because hair must be redyed after four to six weeks due to growth, the fastness required of hair dyes is generally less than that needed for textiles. However, stability is still a problem with many indo dyes (see Section 5.4.3). Some of them... 

The colors of foods are the result of natural pigments or of added colorants. The natural pigments are a group of substances present in animal and vegetable products. The added colorants are regulated as food additives, but some of the synthetic colors, especially carotenoids, are considered nature identical ... 

Apart from the derivatives of p-carotene, other pigments are the anthocyanins, the chlorophylls, cochineal, the betalaines, turmeric, caramel and riboflavin. In this account the historical background in brief, the chemistry of these pigments, their extraction from natural sources and their synthesis will be discussed. The present permitted natural substances and nature-identical synthetic materials (also described by the Food and Drugs Administration, the FDA, as colorants exempt from certification ) is quite small in number. Reference is also made to colourants no longer listed but which have an historical organic chemical significance such as for example brazilin and its relative haematoxylin. 

Each anthocyanidin is involved in a series of equilibria giving rise to different forms, which exhibit their own properties including color. One- and two-dimensional NMR have been used to characterize the various forms of malvidin 3,5-diglucoside present in aqueous solution in the pH range 0.3 to 4.5 and to determine their molar fractions as a function of pH. In addition to the flavylium cation, two hemiacetal forms and both the cis and trans forms of chalcone were firmly identified. In a reexamination, the intricate pH-dependent set of chemical reactions involving synthetic flavylium compounds (e.g., 4 -hydroxyflavylium) was confirmed to be basically identical to those of natural anthocyanins (e.g., malvidin 3,5-diglucoside) in... 

The anthocyanin is malvidin-3,5-diglucoside (Fluka), and the tannins are a sample of leucoanthocyanins extracted from the bark of the maritime pine (Pinus pinaster). The products are not identical to the natural grape pigments nevertheless, it may be assumed that the observed facts correlate, as a first approximation, with red wine color and its changes. 

---