Gum Arabic is a product that has many advantages and uses in various industries.
Further, we analyse in more detail what is Gum Arabic, how it is processed and most importantly – what are the uses and properties of this product.
Gum Arabic (Gum Acacia) is a natural raw material from plant origin. It is obtained from the exudation of acacia species naturally growing in the ‘’Gum Belt’’ region that stretches across the continent from Guinea to Somalia and south of Sahara Desert but the main supply countries are Sudan, Chad, Nigeria.
Gum Acacia is a natural hydrocolloid with polyvalent properties for a wide range of industrial applications. It is used as a film-building agent or surface-protective colloid, it also has outstanding binding, emulsifying, and stabilizing properties. Furthermore, it is a natural food-grade adhesive as well as an encapsulating agent. E number is E 141.
Types of Gum Arabic:
Acacia Senegal – Grade 1 (Hashab)
Acacia Seyal – Grade 2 (Talha)
CHEMICAL STRUCTURE OF GUM ARABIC (GUM ACACIA)
Chemically Gum Arabic consists mainly of high molecular weight polysaccharides and their calcium, magnesium, and potassium salts. On hydrolysis these yield galactose, arabinose, rhamnose and glucuronic acid. Also Gum Arabic consists of a small amount of protein (~0.8% with A. seyal & ~2.0% with A. Senegal gums) associated with the gum structure.
Gum Arabic has been fractionated by hydrophobic chromatography into three principal fractions: Arabinogalactan (AG), Arabinogalactan-protein (AGP) and glycoprotein (GP).
4 STAGES OF HARVESTING AND PROCESSING
Acacia Senegal/tress are tapped after Autumn (October/November) when the tree starts to lose its leaves. Acacia Seyal trees normally exude the gum naturally (Gummosis).
The gum is produced when the tree is subjected to heat or tapping (wounding). It exudes in nodule forms up to 60 mm in diameter. The gum nodules then dry in the sun, forming exudates of Acacia Senegal (transparent to amber colour, hard and glass-like lumps) and Acacia Seyal (amber to brown colour, fragile gum fragments).
The first collection of the exuded gum starts after 4-6 weeks from tapping, followed by 3-5 collections every 2 weeks.
After collection of the gum, the gum is now spread evenly to dry for a few days.
4. Cleaning and Processing
The cleaning process can be Manual, Mechanical and Spray Drying.
- Manual Cleaning – Basic cleaning and bark removal are carried out at the source. The gum that is exported from Africa contains a varying proportion of bark and other extraneous material.
- Mechanical Process – Physical processing to clean, grade and generate a range of different particle sizes from the original lump gum.
- Spray Drying Process –The spray drying process allows the gum to be efficiently purified to give a consistent product. This can then be used directly in applications by customers without recourse to further cleaning, either chemical, physical, or microbiological.
Gum Arabic has many properties that make it unique. These are the main 6 properties:
- Gum Arabic is unique among natural hydrocolloids in that it is highly soluble in hot and cold water. Most gums cannot be dissolved in water at a concentration higher than 5%, but Gum Arabic can yield solutions up to 50% concentration.
- The ability of Gum Arabic to form these concentrated solutions without excessive increase in viscosity is due to the high degree of branching within the gum structure.
- Gum Arabic is insoluble in oils and in most organic solvents.
2. Emulsifying Properties
- Gum from Acacia Senegal is a very effective emulsifying and stabilising agent and has found widespread use in the preparation of varied oil-in-water emulsions.
- Effect of Heat on the emulsion capacity of Gum Arabic – Prolonged heating causes the thermal destruction of Gum Arabic. It results in the denaturation and precipitation of proteins from the high molecular weight AGP and GP complexes.
- Most gums form highly viscous solutions at low concentration (1-5%). However, at such relatively low concentrations of Gum Arabic yields solutions, which are essentially Newtonian in behaviour and have very low viscosities compared to other polysaccharides of similar molecular mass.
- Gum Arabic has a broad range of compatibilities and is compatible with most gums and starches and with most carbohydrates and proteins as well.
5. Sensory Properties
- The Gum Arabic is generally odourless, colourless and tasteless.
6. Nutritional Properties
- Gum Arabic is a complex polysaccharide indigestible to both humans and animals but fermented in the colon to give short fatty acids (SFA), leading to a wide range of potential health benefits. It thus meets dietary fibre definitions.
The typical fibre content of Gum Arabic is more than 85% (AOAC method).
- Due to the complex highly branched Gum Arabic molecule structure, the fermentation is very slow which reduce the bloating side effect.
- Gum Arabic is a Prebiotic soluble fibre that feeds and stimulates the growth and activity if the beneficial bacteria (Probiotic) in the colon i.e. lactobacilli and Bifidogenic bacteria. Probiotic bacteria strengthen the immune system to combat allergies, stress, exposure to toxic substances and other diseases.
- Feeding trials have indicated a complete fermentation of Gum Arabic by gut bacteria when it comprises to >10% of the diet.
- Energy value of 1.7 Kcal/g was recommended by FDA to be used for the calculation of Gum Acacia energy contribution.