Sodium alginate is the sodium salt of the compound alginic acid. It is a natural product that is extracted from the cell walls of brown algae. Sodium alginate is a natural gum and is used to thicken various compounds. It is also used in various chemical processes to bind together other compounds without reacting to them. There are several substitutes for the various uses of sodium alginate, but no one substitute for the compound itself.
Food Uses
Sodium alginate is used to thicken foods and as a preservative emulsifier to help bind processed foods together. It is usually used in food that has a thick or jelly like consistency, such as canned fruit, puddings and even processed meat.
Corn or maize starch may be used as a substitute to thicken the product, but it may change the consistency of the final product.
Fabric Dye Uses
Sodium alginate is used in the process to dye heavy fabric, such as carpets or home textiles. It acts as a emulsifier that thickens the dye and allows it to penetrate into the fabric, but it does not react to the dye or change the color of the dye. It also breaks down with water and washes out of the fabric.
Natural rubber, such as hexane, or other natural gums, such as gaur gum or xantham gum, can be substituted for sodium alginate. Starch thickeners may also be substituted, but they may react to the dye and change the color results.
Scientific Experiments
A solution of sodium alginate has been used in scientific experiments to temporarily freeze cells in place during observation and chemical experimentation.
Potassium alginate and hyaluronic acid, a similar polysaccharide found in animal cells, can be used in a similar way and may be used as a substitute in these experiments.