Quite often in US and European food formulations you will see a number of artificial colours. One in particular is Allura Red AC which is a red azo dye with exceptional stability. It’s also known as FD&C Red 40 and has been a food dye for many years. It has the E number E129 and is permitted in the European Union as a food additive.
The IUPAC name is disodium 6-hydroxy-5-[(2-methoxy-5-methyl-4-sulfonatophenyl)diazenyl]naphthalene-2-sulphonate. It is CAS No. 25956-17-6.
The dye is available as a mineral salt with sodium, calcium and potassium and sometimes with all three in the mix. The addition of the mineral helps make it extremely soluble. The dye was first introducted into the USA as a food colouring agent in 1971.
Sometimes it is prepared as a lake where it is then labelled as Red 40 Aluminium lake or just Red 40 Lake. In the USA is it is permitted in cosmetics, food and many drugs. It is also a tattoo ink. Some of the most popular products containing this dye include beverages, especially soft drinks and those aimed at children. It is now the most popular red colour in general use in the USA and more popular than amaranth (Red 2) and erythrosine (Red 3).
The colour is produced from petroleum distillates and coal tars.
Health & Safety
The ADI is 7mg/kg body weight.
Allura red AC can form a complex with human serum albumin (HSA) although albumins are common carriers of a variety of materials in the blood system. Allura Red AC would on this basis make an effective ligand for general affinity chromatography (Wu et al., 2015). The binding is reversible.
The dye is non-genotoxic in a wide range of gene mutation tests which involved both prokaryotic abnd eukaryotic cells and irrespective of the use of activation or not (Chung et al., 1981; Combes & haveland-Smith, 1982). The dye was however reported to show a direct genotoxic effect when different concentrations of the dye ranging from 9.76 to 5000 µg/mL was incubated with a culture of Saccharomyces cerevisiae at 37°C. Comet assay revealed dose-related DNA damage starting at concentration of 1250 μg/ml, though no positive correlation could be established with exposure time (Jabeen et al., 2013).
Chung, K.T., Fulk, G., Andrews, A. (1981). Mutagenicity testing of some commonly used dyes. Appl. Environ. Microbiol. 42(4) pp. 641-648
Combes, R.D., Haveland-Smith, R.B. (1982). A review of the genotoxicity of food, drug and cosmetic colours and other azo, triphenylmethane and xanthene dyes. Mutat. Res. 98(2) pp. 101-243
Jabeen, H.S., ur Rahman, S., Mahmood, S., Anwer, S. (2013). Genotoxicity assessment of amaranth and allura red using Saccharomyces cerevisiae. Bull. Environ. Contam. Toxicol. 90(1) pp. 22-26
Wu, D., Yan, J., Wang, J., Wang, Q., & Li, H. (2015). Characterisation of interaction between food colourant allura red AC and human serum albumin: Multispectroscopic analyses and docking simulations. Food Chemistry, 170, pp. 423-429 https://doi.org/10.1016/j.foodchem.2014.08.088