Hydrocolloids / Gum
Hydrocolloids are a heterogeneous group of long chain polymers (polysaccharides and proteins) characterized by their property of forming viscous dispersions and/or gels when dispersed in water. Presence of a large number of hydroxyl (-OH) groups markedly increases their affinity for binding water molecules rendering them hydrophilic compounds. Further, they produce a dispersion, which is intermediate between a true solution and a suspension, and exhibits the properties of a colloid. Considering these two properties, they are aptly termed as ‘hydrophilic colloids’ or ‘hydrocolloids’.
The foremost reason behind the ample use of hydrocolloids in foods is their ability to modify the rheology of food system. This includes two basic properties of food system namely, flow behavior (viscosity) and mechanical solid property (texture). The modification of texture and/or viscosity of food system help to modify its sensory properties, and hence, hydrocolloids are used as important food additives to perform specific purposes. It is obvious that several hydrocolloids belong to the category of permitted food additive in many countries throughout the world.
Hydrocolloids have a wide array of functional properties in foods. These include thickening, gelling, emulsifying, stabilization, and controlling the crystal growth of ice and sugar though the basic properties for which hydrocolloids find extensive use are thickening and gelling. Hydrocolloids disperse in water to give a thickening or viscosity producing effect. This water-thickening property is common to all hydrocolloids and is the prime reason for their overall use. The extent of thickening varies with the type and nature of hydrocolloids, with a few giving low viscosities at a fairly high concentration but most of them giving high viscosities at concentration, below 1%.