Patent Blue V
What it does
Blue colour.
How it's made
Synthetic triarylmethane dye.
Patent blue V is a synthetic blue colour used in a limited range of foods and also in some medical applications. It gives a bright blue and is often used in small amounts, sometimes blended with yellows to make greens.
It belongs to the triarylmethane family of dyes and is made by chemical synthesis, building a central carbon atom joined to three aromatic rings and then adding sulphonic-acid groups to make it water-soluble. The particular substituents on the rings give the deep blue colour.
The dye is purified and standardised, with limits on impurities, and supplied as a blue powder or granules. Its permitted food uses are relatively restricted, and it is chosen where a clean blue shade is required.
Possible reactions
Can cause allergic reactions in rare cases.