Views: 0 Author: Site Editor Publish Time: 2022-10-24 Origin: Site
Sodium alginate is a by-product after extracting iodine and mannitol from kelp or sargassum of brown algae. Its molecules are β- D-mannuronic acid（ β- D-manuronic, M) and α- L-Guluouronic acid（ α- L-guluronic, G) is a natural polysaccharide connected by the (1 → 4) key, which has the stability, solubility, viscosity and safety required for pharmaceutical excipients. Sodium alginate has been widely used in food industry and medicine field.
Sodium alginate is a by-product after extracting iodine and mannitol from kelp or sargassum of brown algae. Its molecules are β- D-mannuronic acid（ β- D-manuronic, M) and α- L-Guluouronic acid（ α- L-guluronic, G) is connected by pressing (1 → 4) key. The aqueous solution of sodium alginate has a high viscosity and has been used as a thickener, stabilizer, emulsifier, etc. of food. Sodium alginate is a non-toxic food, which has been included in the United States Pharmacopoeia as early as 1938. Sodium alginate contains a large amount of - COO -, which can show polyanionic behavior in aqueous solution and has certain adhesiveness, and can be used as a drug carrier for treating mucosal tissue. Under acidic conditions, - COO - is converted into - COOH, the ionization degree decreases, the hydrophilicity of sodium alginate decreases, and the molecular chain shrinks. When the pH value increases, the - COOH group continuously dissociates, the hydrophilicity of sodium alginate increases, and the molecular chain extends. Therefore, sodium alginate has obvious pH sensitivity. Sodium alginate can quickly form gel under extremely mild conditions. When cations such as Ca2+and Sr2+exist, the Na+on the G unit will exchange with divalent cations, and the G unit will stack to form a cross-linked network structure, thus forming a hydrogel. The conditions under which sodium alginate forms gel are mild, which can avoid the inactivation of sensitive drugs, proteins, cells, enzymes and other active substances. Because of these excellent characteristics, sodium alginate has been widely used in food industry and medicine field.
The technical process of sodium alginate is as follows: dry or wet seaweed (algae) is crushed, washed with water to remove impurities, extracted with strong alkaline water, and clarified to obtain crude alginate solution, and precipitated by calcium chloride to obtain colored calcium alginate , After decolorization and deodorization, it is treated with acid to remove soluble impurities to obtain alginic acid precipitation, which is reacted with sodium carbonate to obtain sodium alginate, and then dried, pulverized and sieved to obtain sodium alginate powder.
As a thickener for beverages and dairy products, sodium alginate has unique advantages in thickening: the good fluidity of sodium alginate makes the added beverage smoother; and it can prevent the viscosity drop during product disinfection. When using sodium alginate as a thickener, products with larger molecular weight should be used as much as possible, and Ca should be added in an appropriate amount. It can greatly increase the viscosity of sodium alginate.
Sodium alginate is a high-grade stabilizer for ice cream and other cold drinks. It can make ice cream and other cold drinks produce smooth appearance and smooth taste. Since calcium alginate can form a stable thermally irreversible gel, it will not become rough (ice crystal growth) during transportation and storage, and ice cream will not be deformed due to temperature fluctuations. Both the expansion rate and the melting point are improved, so that the quality and efficiency of the product are significantly improved. The product has a smooth, delicate and good taste. The addition amount is low, generally 1-3%, and the foreign addition amount is 5-10%.
Sodium alginate is used as a stabilizer for dairy products and beverages. The stabilized frozen milk has good taste, no stickiness and stiffness, stickiness and hysteresis when stirring.
1. Application in food
Sodium alginate is used to replace starch and gelatin as the stabilizer of ice cream, which can control the formation of ice crystals, improve the taste of ice cream, and stabilize sugared ice cream, ice fruit juice, frozen milk and other mixed drinks. Many dairy products, such as refined cheese, whipped cream, dry cheese, etc., it can prevent the cohesiveness of food and packaging by using the stabilizing effect of sodium alginate, and it can be used as the cover of dairy jewelry, which can make it stable and prevent the cracking of frosted pastry.
Sodium alginate is used as a thickener for salad (a kind of cold dish) sauce, pudding (a kind of dessert), jam, tomato sauce and canned products to improve the stability of products and reduce liquid leakage.
Adding sodium alginate to the production of dried noodles, vermicelli and rice noodles can improve the cohesiveness of the product tissues, make it have strong tension, large bending, and reduce the rate of broken ends, especially when the flour content is low. Adding sodium alginate to bread, pastry and other products can improve the homogeneity of internal tissues and water holding capacity of products, and prolong the storage time. Adding a thermal fusion protective layer to the frozen dessert products can improve the fragrance escape and the melting point performance.
Sodium alginate can be made into various gel foods to maintain good colloidal form without seepage or shrinkage, and it is suitable for frozen food and artificial imitation food. It can also be used to cover fruits, meat, poultry and aquatic products as a protective layer, without direct contact with the air, so as to extend the storage time. It can also be used as the sugar coating of bread, filling filler, coating layer of dim sum, canned food, etc. The original shape can still be maintained in high temperature, freezing and acidic medium. It can also replace agar to make elastic, non sticky, transparent crystal soft candy.
2. Application in pharmaceutical preparations
Sodium alginate has been included in the United States Pharmacopoeia since 1938. Alginate was included in the British Pharmacopoeia in 1963. Alginic acid is insoluble in water, but will expand when put into water. Therefore, traditionally, sodium alginate is used as the adhesive of tablets, while alginate is used as the disintegrating agent of quick release tablets. However, the effect of sodium alginate on the properties of tablets depends on the amount of sodium alginate in the prescription, and in some cases, sodium alginate can promote the disintegration of tablets. Sodium alginate can be added in the process of granulation, rather than in the form of powder after granulation, so that the production process is simpler. Compared with starch, the mechanical strength of the flakes is higher.
Sodium alginate is also used in the production of suspension, gel and concentrated emulsion based on fat and oil. Sodium alginate is used in some liquid drugs to enhance viscosity and improve the suspension of solids. Glycol alginate can improve the stability of the emulsion.
3. Application of Printing and Textile Industry
Sodium alginate is superior to grain starch and other sizing materials when used as reactive dye sizing agent in printing and dyeing industry. The printed textiles have bright patterns, clear lines, high color delivery, uniform color yield, good permeability and plasticity. Algal gum is the best size in modern printing and dyeing industry. Now it is widely used in the printing of cotton, wool, silk, nylon and other fabrics, especially for the preparation of dye shift printing paste.
The Chinese textile sector uses alginate and starch to mix or replace starch to prepare warp sizing, which can not only save a lot of grain, but also make warp fibers lint-free, resistant to friction, and less end-break rate, thereby improving the efficiency of weaving. Alginate is effective on both cotton fibers and synthetic fibers.
4. Application in the pharmaceutical industry
The PS type barium sulfate preparation for gastrointestinal double contrast examination made from alginate sulfate dispersion has the characteristics of low viscosity, fine particle size, good wall adhesion and stable performance.
PSS is a kind of alginate polysaccharide diester sodium prepared from alginate, which has the functions of anticoagulation, lowering blood lipid and lowering blood viscosity.
Using seaweed gum as dental impression material instead of rubber and gypsum is not only cheap and easy to operate, but also more accurate.
Algae gel can also be used to make various dosage forms of hemostatic agents, including hemostatic sponge, hemostatic gauze, hemostatic film, scald gauze, spray hemostatic agent, etc.