It is used as a food additive and is commonly marketed as a flavour enhancer. It has the HS code 29224220 and the E number E621. Trade names of monosodium glutamate include Vetsin, and Accent. It was once predominantly made from wheat gluten, but is now mostly made from bacterial fermentation; it is acceptable for celiacs following a gluten-free diet. Although traditional Asian cuisine had often used seaweed extract, which contains high concentrations of glutamic acid, MSG was not isolated until 1907. MSG was subsequently patented by Corporation of Japan in 1909. In its pure form, it appears as a white crystalline powder; when immersed in water or saliva, it rapidly dissociates into sodium cations and glutamate anions (glutamate is the anionic form of glutamic acid, a naturally occurring amino acid).