What are food hydrocolloids?

Food hydrocolloids are hydrophilic polymers of vegetable, animal, microbial or synthetic origin that generally contain many hydroxyl groups and may be polyelectrolytes. They are naturally present or  added to control the functional properties of aqueous foodstuffs. Most important among  these properties are viscosity (including thickening and gelling) and water binding but also significant are emulsion stabilization, prevention of ice recrystallization and organoleptic properties.