E252 - Potassium nitrate

Preservatives stop bacteria, yeasts and moulds growing in food, which is what allows packaged products to have shelf lives measured in weeks rather than days. The main classes are sulphites (E220 to E228, used in wine, dried fruit, and processed meat), sorbates (E200 series), benzoates (E210 to E219), and nitrites and nitrates (E249 to E252, used to cure meat). Sulphites are the most common asthma trigger among additives and carry mandatory allergen labelling above 10 mg/kg. Cured-meat nitrites form nitrosamines when heated, which is one of the reasons the World Health Organisation classes processed meat as a Group 1 carcinogen.