Tartrazine
What it does
Bright yellow colour.
How it's made
Synthetic azo dye made from petroleum-derived aromatic compounds.
Tartrazine is a synthetic lemon-yellow colour ("azo dye") used in soft drinks, sweets, sauces and many other products where a bright, stable yellow is wanted. It is one of the most familiar artificial colours and dissolves readily in water.
It is made by chemical synthesis from aromatic compounds originally derived from petroleum. The process is a classic azo-dye synthesis: an aromatic amine is treated with nitrous acid to form a reactive "diazonium" compound, which is then coupled to a second aromatic molecule, creating the nitrogen–nitrogen (azo) double bond that carries the yellow colour.
The crude dye is purified and standardised, with limits set on residual starting materials and by-products, and supplied as an orange-yellow powder or granules. In the UK and EU, foods containing tartrazine and certain other azo colours must carry a warning that they "may have an adverse effect on activity and attention in children".
Possible reactions
Linked in some people to hives, asthma and hyperactivity in sensitive children; aspirin-sensitive people may react.