What is sodium alginate?

What is sodium alginate?

1. Source of sodium alginate
Sodium alginate, also known as sodium alginate and kelp gum, is a by-product of extracting iodine and mannitol from the brown algae kelp or sargassum. It is a natural polysaccharide carbohydrate.

2. Physical and chemical properties of sodium alginate
1. Form: Sodium alginate is white or light yellow powder, almost odorless and tasteless.

2. Soluble sodium alginate is easily soluble in water and insoluble in organic solvents such as ethanol, ether, and chloroform. Dissolve in water and become a viscous liquid. Sodium alginate powder becomes wet when it comes into contact with water. The hydration of particles makes their surface sticky, and then the particles quickly adhere together to form clumps. The clumps slowly hydrate completely and dissolve. If water contains other compounds that compete with alginate, sodium alginate is more difficult to dissolve in water. Sugar, starch, or protein in water can reduce the hydration rate of sodium alginate and prolong the mixing time. The pH value of a 1% aqueous solution is 6-8. When the pH is 6-9, the viscosity is stable, but when heated above 80 ℃, the viscosity decreases.

3. Toxicity: Sodium alginate is non-toxic. According to Table A.2 of the national standard GB2760, sodium alginate can be used as a thickener in various foods in moderation according to production needs.

4. In the metal salts of alginate, except for Na ions, K ions, Mg ions, and ammonium ions, which can dissolve in water, all other metal salts are insoluble in water. With this property, calcium alginate gel can be formed by contacting the colloidal solution of sodium alginate with calcium ion. The formation of gel can be controlled by adjusting the pH value, selecting appropriate calcium salt and adding phosphate buffer or chelating agent.

5. Stable and dry sodium alginate is quite stable when stored at 25 ℃ or below in a well sealed container. The nature of sodium alginate solution is stable at pH 5-9. Calcium gel formed by sodium alginate belongs to thermal irreversible gel.