Nor-bixin

Tocchini, L. and Mercadante, A.Z., Extraction and determination of bixin and nor-bixin, by HPLC, in aimatto spice ( colorifico ), Cienc. Tecnol. Aliment., 21, 310, 2001. 

Both bixin and nor-bixin produce orange solutions. Bixin produces an orange solution in oily media while nor-bixin produces an orange aqueous solution. Obviously, bixin is the product of choice for high fat systems while nor-bixin is used in aqueous systems. Nor-bixin is one of the two water-soluble carotenes. 

Nor-bixin is damaged by sulfur dioxide if the concentration exceeds 100 ppm. Acidic conditions or divalent cations, particularly calcium, can cause nor-bixin to precipitate. These problems are tackled by producing nor-bixin preparations with buffers and sequestrants. 

Nor-bixin is relatively stable to heat. The most severe conditions will either isomerise the pigment or shorten the chain. Either of these changes will make the pigment more yellow. Nor-bixin can associate with protein, which stabilises the nor-bixin. The other effect of this association is to redden the colour. 

Annatto is classified as El 60(b). It is extracted from the seeds of the tree Bixa orellana which grows in America, India and East Africa. The extract is a mixture of two pigments, bixin and nor-bixin. Bixin is oil soluble, whereas nor-bixin is water soluble (it is one of the two water soluble carotenes - the other is crocin), and both of the pigments are diapo-carotenoids. Annatto has long been used as a food colouring and also has some uses as a food flavouring. 

Bixin (328) is one of a number of deeply colored carotenoid degradation materials that can be isolated from the pericarp of the fruit of the tree Bixa orellana. Extracts, known as Annatto, are used as yellow food colors E 160(b). Other components include the trans isomer and nor-bixin. The extraction and chemistry of Annatto has been reviewed by... 

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