Source, Production, and Purification

Like larch arabinogalactan, gum arable can be used to make solutions of unusually high concentration and unusually low viscosity, with almost Newtonian flow, which make them quite different from most other gums (14, 18). Gum arable can yield solutions of up to 50% concentration. A 20% solution resembles a thin sugar syrup in body and flow properties. The flow properties of its solutions are typically Newtonian at concentrations up to 40%. 

Addition of salts to a solution of gum arable results in a lowering of both viscosity and interfacial tension. The marked decrease in viscosity, which is proportional to the valence of the cation and its concentration, is usually of no consequence because gum arable is almost never used as a thickening agent. Surface tension is lowered more by monovalent than by divalent cations. Solution viscosity and surface tension are also lowered when the pH is lowered below 4.6. 

Solutions of gum arabic are clear and slightly acidic (pH 4.5-5.0). Maximum viscosity occurs at pH 4.6-6.3 (a rather broad range), with only a slight decrease in viscosity as the pH is raised from 6.3 to 9.0, although again gum arabic is seldom used as a thickener. 

The major uses of gum arabic are in foods, most often in the preparation of emulsions. It is an effective emulsion stabilizer because of its protective colloid action and is widely used in the preparation of flavor oil-in-water emulsions. It produces stable emulsions with citrus and other essential oils over a wide pH range and in the presence of electrolytes, without the need for a secondary stabilizing agent. 

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