Gum Arabic or Acacia is the dried, gummy exudate from the stems or branches of Acacia Senegal or of related species pruces of Acacia. The trees that produce commercial grade of gum Arabic grow primarily in the Sudan and Senegal regions of Africa. The trees are about 4.5-6 meters high and live about 25-30 years. Gum Arabic results from an infection of the trees, which yields the gum only when in an unhealthy condition. To accelerate exudation the bark is cut and the exudate allowed to dry, forming "tears" which are collected. Gum is collected by hand every 10 days during the dry season, which varies from October to June. The gum is graded visually buy sorting the lumps or tears basically into two grades: the clean amber sorts and hand picked selected gum.

• Processing:

Gum Arabic or Acacia is the dried, gummy exudate from the stems or branches of Acacia Senegal or of related species pruces of Acacia. The trees that produce commercial grade of gum Arabic grow primarily in the Sudan and Senegal regions of Africa. The trees are about 4.5-6 meters high and live about 25-30 years. Gum Arabic results from an infection of the trees, which yields the gum only when in an unhealthy condition. To accelerate exudation the bark is cut and the exudate allowed to dry, forming "tears" which are collected. Gum is collected by hand every 10 days during the dry season, which varies from October to June. The gum is graded visually buy sorting the lumps or tears basically into two grades: the clean amber sorts and hand picked selected gum.

• Physical characteristics

Gum Arabic tears, crystals, granules, and powders are almost odorless and tasteless. The color ranges from white to red. The lighter the color, the better the quality of gum.

• Solubility:

Gum Arabic dissolves readily in hot or cold water. A 40% solution produces an excellent mucilage for adhesiveness. Aqueous solutions of over 50% concentrations may be prepared. Gum Arabic is insoluble in alcohol and most organic solvents. Solubility of gum Arabic decreases as the proportion of alcohol to water increases, becoming practically zero in 60% alcohol.

• Viscosity:

Gum Arabic, unlike most other gums, is not normally used where swelling or thickening properties are required. Its viscosity increases slowly up to 25% concentrations and exhibits Newtonian behavior. Above 25% concentrations, the viscosity increases much more rapidly in proportion to gum content. A 30% solution is about 100 cps. At 40% and higher, Gum Arabic is pseudo-plastic as denoted by a decrease in viscosity with increasing shearing stress. Increasing temperature reduces viscosity considerably. The addition of salts or electrolytes affects the consistency of the solutions as well as does pH. Gum Arabic solutions become most viscous near pH 6 to 7. The actual viscosity of gum Arabic is highly influenced by such factors as the age of tree from which the gum was obtained, the rainfall in the gathering area, age of the gum after collection and drying, and the conditions under which it was stored.

• Chemical Characteristics:

Gum Arabic is described as a complex calcium, magnesium, and potassium salt of Arabic acid. The molecular weight of gum Arabic is of the order of 250,000. It has a main backbone chain of (1 3) -linked D-galactopyranose units, some of which are substituted at the c-6 position with various side-chains. the side-chains consist of d-galactopyranose, D-glucuronic acid and L-arabofuranose with additional side-chains on the D-galactopyranose of L-rhamnopyranose. Powdered gum Arabic contains 15% maximum moisture and 0.5% maximum acid insoluble ash. Water solutions are slightly acidic and have pH of approximately 4.5 to 5.5.