Q. Colloidal systems in foods?

A colloidal system is a heterogeneous system. The material that forms the base of the system is called the dispersion medium or the continuous phase. The material that exists in the colloidal condition is called the dispersed medium or the discontinuous phase.

Of the three states of matter (solid, liquid and gas), eight classes of colloidal systems can be formed. Solid in a solid, a solid in a liquid, a solid in a gas, a liquid in a gas, a liquid in a liquid, a liquid in a solid, a gas in a solid and a gas in a liquid.

Colloidal particles, we also learnt, are in motion and are electrically charged. Colloidal systems may be lyophilic or lyophobic. These properties affect viscosity, as even changing the concentration of solutes like sugars and salt and the addition of electrolytes may cause precipitation.

The colloidal property of adsorption makes it useful in cookery, giving protection against precipitation and agglomeration. Another property of imbibition, is the ability to pick up water and swell. Components such as starch, proteins and fat when dispersed in water forms colloids.