TBHQ (tert-Butylhydroquinone)
What it does
Antioxidant for fats.
How it's made
Synthesised from petroleum derivatives.
TBHQ (tert-butylhydroquinone) is a highly effective synthetic antioxidant used to extend the shelf life of fats, frying oils and many processed foods by slowing the oxidation that turns fats rancid. It is particularly valued for protecting oils used at high temperatures.
It is made by chemical synthesis from petrochemical building blocks: hydroquinone is reacted with isobutylene (or a related tert-butyl source) in an alkylation reaction that attaches a bulky tert-butyl group to the hydroquinone ring. This bulky group is what gives the molecule its strong antioxidant power and stability.
The crude product is purified, typically by crystallisation, to give a white to pale-tan crystalline powder. TBHQ is used in very small, tightly regulated amounts because a little provides strong protection, and it is often combined with other antioxidants and with metal-binding agents like citric acid to reinforce its effect.
Possible reactions
May cause nausea in high amounts; sensitivity in some.