Beta-carotene synthetic

JECFA (1974) Joint FAO/WHO Expert Committee on Food Additives. Evaluation of safety of synthetic beta-carotene. Evaluation 18/68. 

The success of the carotenoid extracts led to the commercialization of synthetic carotenoids, some with the same chemical structure as those in the plant extracts and others with modifications to improve their technological properties. The yellow beta-carotene was synthesized in 1950, followed by the orange beta-8-carotenal in 1962 and the red canthaxanthin in 1964. A number of others soon followed, methyl and ethyl esters of carotenoic acid, citraxanthin, zeaxanthin, astaxanthin, and recently lutein. 

The structures of four of the synthetic carotenoids (beta-carotene, canthaxanthin, beta-apo-8 -carotenol, beta-apo-8 -carotenoic acid) are shown in Fig. 8.2. By virtue of their conjugated double bond structure, they are susceptible to oxidation but formulations with antioxidants were developed to minimize oxidation. Carotenoids are classified as oil soluble but most foods require water soluble colorants thus three approaches were used to provide water dispersible preparations. These included formulation of colloidal suspensions, emulsification of oily solutions, and dispersion in suitable colloids. The Hoffman-LaRoche firm pioneered the development of synthetic carotenoid colorants and they obviously chose candidates with better technological properties. For example, the red canthaxanthin is similar in color to lycopene but much more stable. Carotenoid colorants are appropriate for a wide variety of foods.10 Regulations differ in other countries but the only synthetic carotenoids allowed in foods in the US are beta-carotene, canthaxanthin, and beta-8-carotenol. 

Other colourants in use are sunset yellow (Eiio), another synthetic azo dye, and caramel. Caramel colours are manufactured from sugars and are very widely used. This food colour has caused some concern due to effects in experimental animals, for example the reduction in the number of white blood cells in rats. This may be due to the effects of contaminants at the high doses given which may be enhanced by a reduced intake of vitamin B6 in the diet. Annatto and beta carotene are naturally occurring colourants, but in one study 26 per cent of patients with chronic urticaria were shown to react to annatto. 

WS White, KM Peck, EA Uhnan, JW Erdman Jr. Evaluation of the bioavailabUity of natural and synthetic forms of beta-carotenes in a ferret model. Ann NY Acad Sci 691 229-231, 1993. 

Apart from its use as a valuable mordant dyestuff for textiles, cochineal (EEC 120) is still used as a colourant in cosmetics, foods, aperitif and beverages (ref. 194) and is one of the several permitted natural colourants which includes for example p-carotene, betanidin from Beta vulgaris, curcumin from Curcuma tonga, certain anthocyanins and chlorophyll complexes to quote a few structures. Commercial interest in natural products such as cochineal and carminic acid has been reactivated by the increasing pressures to avoid synthetic azo colours, their association with potential carcinogenic attributes and the increasing popularity of green issues. Carminic acid is reputed to possess some anticancer activity (ref. 195,196) and is a distant structural relative of the antibiotics, carminomycin and carminomycinone. 

---