E405, or propylene glycol alginate, is a food additive used in the food industry as a stabilizer, thickener, and emulsifier.
It is widely used in the production of various products such as cream and dairy products, sauces, jellies, confectionery, and even in some medications.
Propylene glycol alginate is considered relatively safe for consumption, however, like any other additive, it may cause allergic reactions in some people.