Also known as sodium alginate, sodium alginate, seaweed gum, alginate, alginate, extracted from natural seaweed polysaccharide carbohydrates. Widely used in food, pharmaceutical, textile, printing and dyeing, paper making, daily chemical products, as a thickener, emulsifier, stabilizer, binder, sizing agent used. Since the eighties has been the application of sodium alginate in food have been further expanded. Sodium alginate is not only a safe food additives, and can be used as food or efficacy of bionic food substrate, because it is actually a natural fiber, can slow the absorption of fat, sugar and bile salt, with lower serum cholesterol, blood triglycerides and blood sugar, can prevent hypertension, diabetes, obesity and other modern diseases. It can inhibit the intestinal tract of harmful metals such as strontium, cadmium and lead accumulation in the body, precisely because of the important role of these sodium alginate, at home and abroad has become increasingly valued by the people. The Japanese put food rich in sodium alginate as "longevity food", the Americans called it "wonderful food additive." Alginate (Alginate) is present in brown algae class natural polymer, is extracted from brown algae or bacteria in a natural polysaccharide, similar to the extracellular matrix glycosaminoglycan GAGs, no subacute / chronic toxicity or carcinogenicity response can be used as edible food additives, can also be used as scaffolds for medical purposes, with good biocompatibility . Alginate is Guluo uronic acid (denoted as G above) and its stereoisomers mannose acid (denoted as M above) composed of two structural units, these two structural units in three ways (MM section GG MG section and paragraph) by α-1, 4 glycosidic bonds linked to form a non-linear block copolymer side chains. Alginate is easy to combine with a number of divalent cations to form a gel. Moreover, the mild sol-gel process, a good biocompatibility of alginate for the release or embedded as a drug, protein and cell microcapsules. When the carboxyl group on the 6 and sodium ions to form the alginate salt (Sodium Alginate). Higher classification of sodium alginate. From the structure on the points, can be divided into high G / M ratio, the G / M ratio, low G / M ratio of three. From the viscosity of the points, can be divided into low viscosity, medium viscosity and high viscosity sodium alginate. From the purity of the points, can be divided into industrial, food and medical three levels. For different quality of alginate gel beads structure is significant. Generally believed that the high G / M ratio, suitable for use in the preparation of low viscosity sodium alginate gel beads. Moreover, when plastic beads used for biological engineering, the medical grade alginate should be selected.