Explain the Properties of Gum tragacanth
Gum tragacanth swells in water to give thick viscosity dispersions or pastes similar in texture to soft gels. The viscosity shows a sharp rise as the gum concentration increases, but deceases with increasing shear rates in typical pseudoplastic fashion. Rheologically, tragacanth show pseudoplastic behaviour, typical of most gums.
In general, tragacanth is fairly stable over a wide pH range even at extremely acidic conditions (pH 2). For this reason it has been widely used in food products, such as salad dressings where stable viscosities at low pH are required.
Gum tragacanth has well defined surface active properties and produces a rapid lowering of the surface tension of water at low concentrations, thus used as an emulsifying agent. Together with its viscous nature and acid stability, gum tragacanth promotes stable emulsions and is known as a very effective emulsifying agent.
Gum tragacanth is compatible with most gum systems and viscosities are usually additive when it is used in mixed gum systems. Gum Arabic when added to gum tragacanth lowers the viscosity of gum tragacanth and produces emulsions with superior smooth quality citrus oil, cod liver oil, linseed oil and mineral oil. Preservatives are necessary in order to maintain long term shelf stability of gum tragacanth containing solutions and the choice will depend on the finished product and formulation. Glycerol or propylene glycol is an excellent preservative for many emulsions.