What it is
E210 (benzoic acid) is a preservative found naturally in cranberries, prunes, and other fruits; commercially produced by chemical synthesis from toluene.
Why it matters
Active against yeasts and moulds. Common in soft drinks, fruit-based sauces, jams, pickles. The related sodium, potassium, and calcium benzoates (E211–E213) are far more widely used because they are water-soluble.
What to do
Always vegan.