Agar agar, or simply called agar, is a hydrocolloid generally made from Gelidium and Gracilaria, commonly used as a gelling agent and thickener in food. The European food additive number for it is E406. It is the first used phycocolloid with a history of 300 years, much earlier than alginates and carrageenan, which also are extracted from marine algae seaweed.

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