Citric acid

Citric acid is an acid found naturally in citrus fruit and also made for food use by fermentation. It gives foods a sharp, sour taste and can help control acidity; on ingredient lists it may appear as E330.

Not spoon for spoon: citric acid powder is much more concentrated than lemon juice and adds no liquid or lemon flavour. Use a recipe that specifies citric acid, or follow a tested conversion for that particular recipe.

For a tangy coating, mix a little citric acid into sugar and taste a pinch before coating sweets; it is intensely sour, so start sparingly. Keep the mixture dry, as moisture makes it clump.

Keep it in a tightly sealed, clearly labelled container in a cool, dry cupboard. Use a dry spoon and keep it separate from salt and sugar so it is not mistaken for either.

No. Citric acid gives food a sour taste and adjusts its acidity, while ascorbic acid is vitamin C and is often used to slow browning. They are not interchangeable in recipes.

Acidity helps pectin form a gel, so citric acid may be included when fruit is not acidic enough. Follow a tested jam recipe for the amount: adding it freely can make the jam sharply sour and affect the set.