Gum arabic, also known as gum acacia is a natural gum exudate made of hardened sap. Its taken from two species of the acacia tree; Acacia senegal and Acacia seyal which are distributed over tropical and subtropical areas of Africa, India, Australia, Central America, and southwest North America. Two countries that are commercially important for the export of gum arabic are Sudan and Chad.
The production begins with the farmer cutting or wounding the plants so that they will weep. The sap exudes, or oozes, where the bark has been cut and then dries into clumps called "tears" . It is then harvested and sold where it is made into a translucent liquid or an amber powder. The quality of gums depend three important concepts:
- the variety of acacia, where the acacia senegal being the most desirable by most accounts.
- the "sort" that the gum is purchased from. The "sorts" are equivalent to grades of purity. The higher the sort, the more expensive and purer the gum. The lower the sort; the cheaper, and also the more bark, branches, and dirt, that will be mixed in with the gum arabic.
- the color and quality of the gum is different from year to year, depending on the climate. The hardened extrusions are collected in the middle of the rainy season ( begins in July), and exported at the start of the dry season (November).
What is it ?
Technically, gum arabic (acacia senegal) is a very complex, branched polysaccharide that is classed in a group of substances called arabinogalactan proteins. It is comprised mostly of several different sugar units (galactose, arabinose, rhamnose, and glucuronic acid) and a very small amount of protein. Although these amino acids comprise of only around 1-2% of the total gum, without them it would not function as an emulsifier; the other 98-99% is made of the above mentioned sugars.
What do we use it for ?
Its thickening power is much less than other gums and has emulsifying properties that enables essential oils, like lemon and orange, to be incorporated into soft drinks and soft drink syrups. Gum arabic can be used to bind food substances, like soup and sauces, as well as to smoothen textures, or to hold flavoring. The gum is used in chocolate candies, chocolate glaze, cocoa, gummy candies, marshmallows, as a wine clarifier, marzipan, an aroma encapsulator, and beer.
- hydrate in cold or hot water under shear.
- extremely soluable in water and is not very viscous at low concentrations.
- viscosity is most stable at pH 3-9.
- solutions at high percentages display excellent adhesive properties.
- High viscosities are not obtained until concentrations of about 40-50% are obtained.
- At concentrations up to 40%, solutions exhibit Newtonian behavior.
- At concentrations above 40%, solutions exhibit pseudoplastic behavior.
- Freeze/Thaw stable.
1% to 40 %. Flavor oil emulsions, at 25%.
<u>Further Reading/Research:</u> Hydrocolloids: Practical Guides for the Food Industry (Eagan Press Handbook Series), Andrew C. Hoefler, Martin Chaplin: Gum Arabic, London South Bank University, web page.