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 user:siti.zainun.nasirGum Arabic A functional hydrocolloid for beveragesuser:siti.zainun.nasir
Gum Arabic is the gummy exudates from African Acacia specieswhich naturally grow in the "Gum Belt" of Africa, a region extending itself from the Sudan through Chad up to Nigeria. It is defined as a water soluble polysaccharide of the hydrocolloid group, but it shows properties that clearly differ from those of other hydrocolloids such as Guar Gum, Locust Bean Gum or Agar-Agar. Gum Arabic solutions have an almost Newtonian behaviour although their average molecular weight is 350 000 g/mol, i.e. their viscosity remains equal even when the shear rate is modified. This behaviour is usually observed in pure water or solutions with salts or low-molecular organic compounds. Gum Arabic liquid solutions with a high gum concentration up to 50 percent can be easily prepared.

Gum Arabic can be subdivided in three structural groups, but, as far as its functionality is concerned, the arabinogalactan protein (in short AGP) is the relevant one. The two other groups are the arabinogalactan and the glycoprotein. In the case of AGP, the arabinogalactan components are linked to a protein chain. The arabinogalactan consists of a b r a n c h e d framework of arabinose and galactose, the end fragments of which also contain rhamnose and glucuronic acid. This gives a molecule with a very compact and almost globular structure. As far as the emulsifying properties are concerned, it is crucial that the protein chain is easily attainable at the periphery of the general structure. For this polysaccharide to be used as an emulsifier, it is assumed that the protein chain of the AGP is taken up to the oil-phase of an oil-in-water emulsion whereas the arabinogalactan components constitute the hydrophile element. Arabinogalactan also plays an important role in the stabilizing properties of Gum Arabic. This is clearly shown by the fact that emulsions using AGP only are far less stable than emulsions with a complete Gum Arabic. The emulsifying properties of Gum Arabic are directly influenced by the botanical type of the acacia tree, the nature of the soils and the climate. Due to the thermic sensitivity of its proteinic components, the emulsifying properties of Gum Arabic can decrease under the influence of heat. It is therefore very important to select the adequate qualities for the use in beverages, flavours a/o aromatic emulsions.

VERSATILE FUNCTIONALITY FOR A WIDE RANGE OF BEVERAGE APPLICATIONS - Functional beverages, wellness drinks, diet products and "light" liquid foodstuffs with nutritional claims largely use the low-calorieand high-fibre content of Gum Arabic, no matter under which form, i.e. pieces, granules, aqueous solution or purified powder. - In aromatic solutions, oil-in-water and water-in-oil systems, the most significant function of Gum Arabic is its emulsifying, suspending and stabilizing ability, keeping all recipe elements in a perfect balance, thus providing a homogeneous texture to the beverage and a pleasant mouth feel. - For flavours in spray-dried powder form, Gum Arabic acts as an emulsifier for the spray-emulsion and as a film-forming and encapsulating agent that prevents the essential oil drops from oxidation in the finished product. - Gum Arabic gives excellent results in cloudy beverages, in which the flavour emulsions guarantee the required turbidity in the finished product, which is due to the change of the refractive index on the emulsified oil-phase. This especially in citrus oil emulsions. - The flavour release in emulsions or spray-dried flavour powders on Gum Arabic basis is perfect due to its fully neutral taste and odour. In flavoured milk beverages, Gum Arabic is used as a suspending agent and stabilizer of the flavour particles in the milk, avoiding their p r e c i p i t a t i o n and giving an homogeneous structure and smooth texture to the milk drink. - The naturally clearing or clarifying properties of Gum Arabic are known by the wine producers. Gum Arabic is adaptable to any production method, processing technology and equipment.