There are many thousands of natural and synthetic organic dyes, some of which are permitted in food products and some of which are not. Examples of natural organic dyes include cochineal, saffron and woad. Man-made azo dyes make up more than 75% of all organic dyes and colourants and these are no longer permitted for use in many countries if they produce one of the listed metabolites, often found due to a degradation of one or more azo-groups:
- 4-Aminobiphenyl
- 4-Amino-2’,3-dimethylazobenzene (o-Aminoazotoluene)
- 4-Aminophenylether (4,4’-Oxydianiline)
- 4-Aminophenylthioether (4,4’-Thiodianiline)
- 4,4’-Benzidine
- Bis-(4-aminophenyl)-methane (4,4’-Diaminodiphenylmethane)
- 4-Chloroaniline (p-Chloroaniline)
- 4-Chloro-2-methylaniline (4-Chloro-o-toluidine)
- 2,4-Diaminotoluene
- 3,3’-Dichlorobenzidine
- 3,3’-Dimethoxybenzidine (o-Dianisidine)
- 3,3’-Dimethylbenzidine (o-Tolidine)
- 4,4’-Diamino-3,3’-dimethyldiphenyl methane
- 2-Methoxy-5-methylaniline (p-Kresidine)
- 4-Methoxy-1,3-phenylenediamine (2,4-Diaminoanisole)
- 4,4’-Methylene-bis(2-chloroaniline)
- 2-Methyl-5-nitroaniline (2-Amino-4-nitrotoluene)
- 2-Naphthylamine
- o-Toluidine
- 2,4,5-Trimethylaniline
