SPHERIFICATION: SODIUM ALGINATE
Alginates are extracted from brown seaweed and are available in sodium, ammonium and potassium derivatives. They are soluble in both hot and cold water, and can thicken and bind. In the presence of calcium and an acid some alginates can form resilient gels.
The chemical compound sodium alginate is the sodium salt of alginic acid. Its form as a gum, when extracted from the cell walls of brown seaweed (particularly kelp grown in the cold water regions of Ireland, Scotland, North and South America, New Zealand, Australia, and South Africa) is used by the food industry to increase viscosity and as an emulsifier. It is also used in indigestion tablets. Sodium alginate has no discernable flavor.
Sodium alginate works as a cold gelling agent that needs no heat to gel. It gels in the presence of calcium compounds. Most commonly used with calcium chloride to make caviar and spheres. It dilutes while cold with strong agitation. Heat is not needed to produce spherification. Sodium alginate can also be used to produce foams.