Gum arabic
See also: Gum
The gum arabic whose gum Senegal is only one variety, consists of a Exsudat of falling sap solidified, amalgamated naturally or by incision, on the trunk and with the foot of trees, of the family of the acacias. She is collected mainly in Saharan Africa (the Maghreb, Mali, Senegal, Chad, Egypt, Sudan…)
- the gum arabic is a acid Polysaccharide strongly ramified which is appeared as mixtures of salts of Potassium, of Magnésium and Calcium. The monomeric elements of l.acide free (arabic acid) are D Galactose, the L Arabinose, the L Rhamnose and the acid D Glucuronique. It is admitted that the gum arabics are composed at least of two fractions of polysaccharides of different structures. The fraction of higher molecular mass contains a share of amino-acids modest but determining for its properties. The average molecular mass indicated oscillates between 200 and 300 let us kilodaltons.
- One finds gum arabic in the trade in the form of powder or of more or less round not ground crystals of white yellow color to brownish yellow. Surface external of the crystals is matt and cracked and their breaks are vitreous; they are often also crossed by fine cracks. The gum is insipid and odorless. It is water soluble, insoluble in alcohol.
- Even in concentration from 30 to 40%, the gum arabic remains far from viscous. It is used mainly as emulsifier, especially for oils of citrus fruits, protective colloid in the emulsions and supports for the flavors. The gum arabic has however only one secondary importance in the industry of the foodstuffs. Its food code name is E414.
Types of gum arabic
- hard Gum arabic or Kitir (gum lasts of the 1st quality on the worldwide market being identified with Sudanese Kordofan and Nigerian) produced by Acacia Senegal obtained by bleeding and marginally, Acacia polyacantha . According to the definition of the food Codex, only the gums produced by Acacia Senegal and Acacia seyal have the gum arabic official designation “”. The qualities of gum most assessed on the market are those of the Ferlo (Senegal) and of Kordofan (Sudan).
- the other gums result from the natural exsudat of the Acacia seyal and to kitir which indicate also at the same time Acacia laeta , Acacia will millifera and Acacia gourmensis and also Sterculia will setigera friable Gum arabic or: Talha produced by Acacia seyal and, marginally, Acacia sieberianna and Sterculia will setigera .
- Finally the gum resulting from the Acacia laeta .
History
- the gum arabic is certainly oldest and most known of all gums. The Egyptians knew it under the name of kami and would have used it as of the third dynasty (2650 av J.C) to ensure the cohesion of bindings of mummies.
- the manuscript of Ebers (a medical papyrus written towards 1550 before the Christian era) proposes the use of gum of acacia or gum arabic like means of contraception associated with dates.
- At the 15th century, of the European navigators discovers gum arabic on the coasts of Senegal and the current Mauritania. The 18th century, a “war of bloody and keen gum” makes it possible France to obtain the monopoly of its trade on the west coast African.
- At the beginning of the 20th century, the England disencloses the other large cradle of gum arabic while making build a railway line between Eloubeid heart of the area of Kordofan and Port Sudan. England and the France transform into Europe the gum which their merchant fleet conveys starting from the counters: the gum becomes a food product of initiates, traded by the two colonial powers.
Manufacture
- Sudanese method known as “tapping”: the trees are barked with the cover (Farrar) instrument with small blade with which one carries out two longitudinal notches parallel not very deep from 40 to 60 cm length then the bark is torn off with the hand. That is to say the “tapping tool” the use of an instrument in the shape of halberd allowing to carry out bleedings at a long distance from the trunk. That is to say the square method which consists in making with the “farrar” three to four squares on a branch or the trunk, this led to obtain a good intensity of the gemmage and to avoid the tree withering. This in the strict respect of the period of gommose: from December to June.
- the gum runs out naturally by wounds of the bark of the trees; by increasing the number of those per action of the hand of the man, one can easily increase the output.
- the production can however be very variable according to the trees, of 20g with 2000g by individual; it is on average of 250g by tree.
Production
- Acacia Senegal provides 90% of gum arabic marketing. It exceeds in quality all the other acacias. The gum is a very important product of export. The sold quantities depend much on the climate. The output varies much from one tree and one year to another and oscillates between 100 and 1000 G (up to 10 kg in Sudan), but with an average of at least 250 G in a good settlement (with the kordofan 500 to 2000 feet per ha).
- the friable gum is of less quality and thus paid less expensive (4 to 5 times less expensive than gum of Senegal Acacia in 1995, but only 50% less expensive in 2001), which partly explains the absence of intensification of its production (Muller, 1995).
- However, a recent interest on behalf of the industrialists for friable gum appeared, dependant on developments in the technologies of its development, in particular on market segments where the hard gum is not competitive any more.
- Nearly 900 species of acacias is likely to provide gum arabic, distributed above all in the tropical belt of the sphere. The greatest production very quickly concentrated in Africa, being worth its other gum Senegal name to him, secretion of various acacias (leguminous plants). 80% of the production come from the Senegal Acacia (in Sudan), the remainder is divided per half between the Acacia laetia and the Acacia seya.
Use
In the countries of production
In Chad, the gum is used in several forms:Food
In Ouaddaï, the peasants produce a mixture containing gum arabic and of the fruits of Balanites called “sarné” in local Arabic. The tradesmen of the large Katako market sell it like a delicacy to be chewed.
Textile
In West Africa, the gum arabic is used like agent of solidification and brightness of the basins, fabrics of damask cotton very snuffed for the clothes industry of clothing of pageantry.
Care
Gum arabic pulp is been used for the woman right after the childbirth; to look after the furoncles; for the treatment of the wound, skin diseases, leprosy, dysentery, etc.
Construction
The masons use it to ensure the impermeability of the roofs (at the base of clay and straws); The painters mix it with lime (1/10e quantity of lime used) to paint the walls of the houses.
Others
They use it to produce ink of the Koranic school to write the verses crowned on their wood shelves: walhans; The craftsmen use it for certain dyeings.
Europe
Well-known for the joining of the labels, the envelopes or the stamps (Paper gummed), the gum arabic has today many other employment, of which agribusiness industry (E414).In enology, the gum of Verek acacia is used to stabilize the dyes of the red wines and to reduce the risks of cupric breakage of the white wines and rosy. The gum of Seyal acacia is less powerful for the prevention of the disorders and deposits but makes it possible to improve organoleptic qualities of the wine (contribution of roundness, reduction in the feeling of Astringence). When the amount used increases, one observes a reduction in the aromatic power of the wine (effect of Adsorption of the flavors).
The gum arabic intervenes in the manufacture of the Belgian Cuberdon.
In the field of paintings, all the traditional gouaches and watercolours have as a binder an aqueous solution with high gum arabic concentration. It is also the best fixative for the fatty or thin pastels.
The gum arabic between also in the manufacture of certain incenses where it with the property of binder.
The gum arabic is also used in the manufacture of sheets to roll for the smokers.
Toxicity
The gum arabic is a strong allergen which can cause asthma attacks if it is inhaled (in the form of vapor).
Economy
In 9 years, from 1991 to 2000, the worldwide market of gum arabic placed from 32.000 to 45.000 tons, that is to say a progression of 40%, calculated on average mobile over 3 years, in order to smooth the variations of order and delivery from one year calendar to another. Chad passed from 10% to 25% of market shares and it almost absorbed the potential of development of these 10 last years. Sudan preserves a half of the market and Nigeria a fifth. The remaining shares (5%) are atomized between ten country. Chad continues to take market shares and develops commercial relations with 14 third country, whereas Sudan trades with 26 countries and Nigeria 9 countries. France is always the world leader of the importing countries and gum arabic re-exporters. In ten years, this remote country Great Britain which makes nothing any more but 1/10e market. India and the United States, as some countries of Eastern Europe and South America, import gum arabic more and more.