E405: Propane-1‚2-diol alginate

What is E405?

E405 is propane-1,2-diol alginate, commonly called propylene glycol alginate (PGA). It is a modified form of alginic acid, a natural carbohydrate from seaweed, in which some of the acid groups are linked to propylene glycol.

Origin and production

PGA is produced by extracting alginic acid from brown seaweeds such as kelp and then reacting it with propylene oxide. The result is a cream-coloured powder that dissolves in water.

Why is it used?

Unlike ordinary alginates, PGA remains stable in acidic conditions, so it is used to thicken and stabilise salad dressings, sauces and fruit drinks. It is also well known for stabilising beer foam and appears in some cakes, pastry dough and frozen desserts.

Vegan, vegetarian and halal

E405 is derived from seaweed and made without animal materials, so it is suitable for vegans and vegetarians. It raises no particular halal or kosher concerns.

Safety and regulation

Propylene glycol alginate is authorised as a food additive in the European Union, with maximum levels for specific foods. EFSA re-evaluated it in 2018 and did not identify a safety concern at reported uses.

Common in