Natural pigments toxicology

In recent decades, the synthetic colorant market has dechned, to the benefit of the natural-oriented market and consumers. Excluding FD C Red 40 and Red 28, the synthetic colorants are now as well accepted as they were. In addition to the decreasing enthusiasm for chemicals in food, the high costs of toxicological studies also inhibit the development and approval of new synthetic colorants. The existing technologies used for the extraction, concentration, and purification of natural plant pigments to be used as food colorants still produce lower yields and the final products are still expensive. 

Some materials, by either their physicochemical or their toxicological natures, generate difficulties in the performance and evaluation of dermal irritation tests. The most commonly encountered of these problems are due to compound volatility, pigmented material, and systemic toxicity. 

Lipid oxidation. Lipid oxidation is normally observed as a product discoloration and can be exacerbated with excess levels of bleach. It is catalyzed by metal ions, enzymes, and pigments. Acidic compounds can be used to complex the metal ions. Synthetic antioxidants, such as butylated hydroxtoluene (BHT) and butylated hydroxyanisole (BHA) can be added to the product, but are limited and coming under increased scrutiny due to toxicology concerns. It may be preferable to use natural antioxidants such as lecithin or vitamin E or to dry under vacuum or in an inert (nitrogen, steam) atmosphere. 

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