Gum Production Phases

1. GUM ARABIC VEGETATION

Strangely, Gum Arabic is only produced by trees that are in an unhealthy condition. Gum yields are improved by natural factors that lessen the vitality of the trees – hot weather, poor soil, lack of moisture, etc.

It is important to remember that a damaged tree will give a larger yield of gum. Thus, the natives will cut and strip the bark from a tree and return later to remove the tears of gum that form in the wounds or scars.

Within 3 - 8 weeks, the gum will start to collect in the wound, but this depends on the weather conditions. Gum droplets are about 0.75 - 3 inches in diameter, and they gradually dry and harden on exposure to the atmosphere. A young tree will yield 400 - 7000g annually.

The dry season lasts from October to June and the gum is collected every 10 days. During the rainy season no gum is formed since the trees are in full bloom. After collection, the gum is brought from the farms and stands to villages. From there it’s transported to market. In the Sudan, the gum is auctioned (under government supervision) and this usually sets the world price.

2. POST-HARVEST HANDLING

At present little cleaning or sorting is undertaken by the producer (collector) of the gum. Some degree of cleaning and sorting may be undertaken by small village traders to whom the producer sells his gum, but it is usually undertaken by the large traders after it has been sold and prior to selling it to the Gum Arabic Company (GAC). If the GAC buys the gum, it cleans and sorts at its own warehouses in the regional centres of the gum belt.

On arrival at the GAC depot at Port Sudan, every consignment of GUM HASHAB is re-cleaned, sorted and graded in preparation for export.

After collection, the gum is brought back to the villages, and when there is a sufficient quantity, it is transported to warehouses.

3. CLEANING PROCESS

Prior to sale, there is a basic cleaning process. This cleaning process is labour intensive and includes such methods as:

•    Crude sieving

•    Hand selection

•    Hand grading and picking of bark etc

The main purpose of this cleaning process is the removal of sand, bark and any extraneous material.

4. GRADING PROCESS

 The subsequent phase involves grading into the following grades/qualities of Sudanese gum on the basis of colour, clarity and cleanliness:

1.    Hand picked selected or HPS (selected sorts) - This ensure a pale uniform colour and freedom from extraneous material.

2.    Cleaned and sifted (cleaned sifted sort) - This is what is left after the hand picked selected is taken away and the siftings are removed.

3.    Cleaned (cleaned amber sorts) - This is the standard grade used throughout the world. Here, siftings are still present, but the dust is removed.

4.    Siftings - This is the material originated from the production of cleaned and sifted. It comprises of fine particles of gum with a proportion of fine bark and sand.

5.    Dust - This is produced from the cleaning process. It comprises of very fine particles of gum, sand and clay/earth.

Different grading systems are used in other exporting countries, and although Sudanese production is more tightly controlled, good quality Nigerian or Chadian grades from reputable dealers can match Sudanese material.

Fields of Application.

Gum Arabic has many fields of application as a condensing, emulsifying, structuring agent, as well as a stabilizing agent for aromas and essential oils in beverage production, in confectionery industry for the production of gumdrops, lozenges, sweets, and as foam stabilizer in the production of soft candies and toffees.       

                                                                         lozenges

                                                                         lozenges

  

                                                                        gumdrops                    

                                                                         toffees.

                                                                            toffees.

                                                                      soft candies

• Bakery 
• Gum arabic is widely used in the baking industry for its low water absorption properties.The gum is      cold  water soluble and have impressive adhesive properties for use in glazes and toppings.

• Confectionery
  
  

  Gum Arabic has been used widely in the confectionery industry. With most confectionery products, Gum Arabic has two important functions - to retard or prevent sugar crystallization and to emulsify the fat and keep it evenly distributed throughout the product. For prevention of sugar crystallization, Gum Arabic finds its greatest application in confections in which sugar content is high and moisture is low, e.g., in jujubes and pastilles. With theses products, the technique of incorporating the flavors is extremely important. Usually, the Gum Arabic is dissolved in water and the solution is filtered, mixed with sugar, and boiled. The flavor is added with a minimum of stirring to prevent formation of bubbles or opaque spots.
  The second function, as a fat emulsifier, is essential to keeping fat distributed uniformly throughout an easily oxidizable, greasy film. This property makes Gum Arabic extremely useful as an emulsifying agent in caramels and toffees.
• Flavors
  
  

  The emulsification properties of Gum Arabic are utilized in various liquid flavor emulsions. Many citrus oils and other beverage flavor emulsions utilize the emulsification properties of the Gum. When used as a flavor fixative, the superior film forming ability of Gum Arabic makes it ideal for protecting the flavor from oxidation, evaporation and absorption of moisture from the air.
• Brewing
  It is used as a foam stabilizer and agent to promote adhesion of foam to glass.

• Pharmaceuticals
  
  

  Gum Arabic suspending and stabilizing properties are employed to suspend insoluble drugs and to prevent the precipitation of heavy metals. Its emulsifying property is used for calomine, magnesia, and kaolin suspensions and liquid petrolatum and cod liver emulsions. Many cough drops and syrups utilize Gum Arabic because of its demulcent of soothing characteristics. Gum Arabic is used as an adhesive and binder for pharmaceutical tablets as well as in their coating.
• Cosmetics
  As a protective colloid, Gum Arabic is used in creams, lotions, mascaras and cake cosmetics.

• Printmaking
  Gum arabic is also used to protect and etch an image in lithographic processes. Ink tends to fill into white space on photosensitive aluminum plates if they do not receive a layer of gum. In lithography the gum etch is used to etch the most subtle gray tones. Phosphoric acid is added in varying concentrations to the gum arabic to etch the darker tones up to dark blacks. Multiple layers of gum are used after the etching process to build up a protective barrier that ensures the ink does not fill into the whites pace of the image being printed.

• Inks
  Gum Arabic is an important constituent of many special purpose inks. Water color and quick drying inks utilize the suspending and binding properties of Gum Arabic.
• Textiles
  Gum Arabic gives body in finishing silk and rayon fabric without loss of transparency. It is also used as a sizing and finishing agent in printing formulations for imparting designs or decorations to fabrics.

• Painting and art
  
  Gum arabic is used as a binder for watercolor painting because it dissolves easily in water. Pigment of
  any color is suspended within the gum arabic in varying amounts, resulting in watercolor paint. Water acts as a vehicle or a diluent to thin the watercolor paint and helps to transfer the paint to a surface such as paper. When all moisture evaporates, the gum arabic binds the pigment to the paper surface.
• Lithography
  In lithography, Gum Arabic is used as a sensitizers for lithographic plates as an element in the light          sensitive composition and as an ingredient of the fountain solution.

• Photography
  
  The historical photography process of gum bichromate photography uses gum arabic mixed with ammonium orpotassium dichromate and pigment to create a coloured photographic emulsion that is sensitive to ultraviolet light. In the final print, the gum arabic permanently binds the pigments onto the paper.
  
• Pyrotechnics
  
  Gum arabic is also used as a water soluble binder in firework composition.
  
  
  
  
  
   
   Powdered gum arabic for artists. One part 
     gum arabic is dissolved in four parts distilled
      water to make a liquid suitable for adding to 
                                                                   pigments.

The origin of gum arabic

The origin of gum arabic tree dates back to 4.000 years ago: the Egyptian artisans appreciated its sticky qualities, using it both as a binder for papyri pigments and as a thickener in cosmetics an for mummification.

Gum Arabic is a natural vegetal resin from in the famous "gum belt", that is the zone including different regions of Sudan; this resin is obtained from two different species of acacia growing in the' gum belt', or Sahel zone in South Sahara, which includes different regions of Sudan.

This resin is obtained through special tapping's made on the trunk of the Acacia Senegal tree (for alimentary sector, pharmaceutical industry and beverage) and Acacia Seyal (for oenological and biotechnological applications).

The resinous liquid which comes out of the tapping's to heal the cuts on the bark, thickens on contact with the air, forming a hard and glassy gum. This process is called "gummosis" and usually lasts from 3 to 8 weeks.

  Acacia Senegal tree

The Gum Arabic in Sudan

Gum Arabic is the trade name for a natural forest product of the genus Acacia and is mainly obtained from Acacia Sengal commonly known as ( Hashab ).
The species has a wide distribution and remarkable adaptability. It is essentially a semi-arid zone species but, it so adaptable that it is not only drought resistant but also  forest hardy.It can regenerate naturally from seeds or vegetatively from copies. The main area of its occurrence is the central part of Sudan where is species is uniform in pure stands giving Sudan the advantage of being the biggest producer and exporter of the best quality Gum Arabic, supplying 80% of the annual world requirements.

Another important comparative advantages is that Sudan it occurs both wild and cultivated in wide area giving the advantages if economies of scale.

Historical Background:
Gum Arabic was known as an article of commerce since the year 400 B.C. and was widely used in Egypt during the Pharaoh 's Civilization in preparation of ink, water colours and dyes the name :GUM Arabic was derived from the fact that it was shipped to Europe from Arabian Ports in the old days.  Gum Arabic is the therefore, long established in the world's Markets. 

Production

While gum arabic has been harvested in Arabia, Egypt, and West Asia since antiquity, sub-Saharan gum arabic has a long history as a prized export. The gum exported came from the band of Acacia trees which once covered much of the Sahel region: the southern littoral of the Sahara Desert running from the Atlantic to the Red Sea. Today the main populations of gum producing Acacia species are harvested in Mauritania, Senegal, Mali, Burkina Faso, Niger, Nigeria, Chad, Cameroon, Sudan, Eritrea, Somalia, Ethiopia, Kenya and Tanzania. Acacia senegal is tapped for gum by cutting holes in the bark, from which a product called Kordofan or Senegal gum is exuded. Seyal gum, from Acacia seyal, the species more prevalent in East Africa, is collected from naturally occurring extrusions on the bark. Traditionally harvested by semi-nomadic desert pastoralists in the course of their transhumance cycle, gum arabic remains a main export of several African nations, including Mauritania, Niger, Chad, and Sudan. The hardened extrusions are collected in the middle of the rainy season (harvesting usually begins in July), and exported at the start of the dry season (November). Retrieved 2008-07-10.</ref> Total world gum arabic exports are today (2008) estimated at 60,000 tonnes, having recovered from 1987–1989 and 2003–2005 crises caused by the destruction of trees by Desert locust.Sudan, Chad, and Nigeria, which in 2007 together produced 95 percent of world exports, have been in discussions to create a producers' cartel.

 

 Acacia seyal from Paul Hermann Wilhelm 

Aubert's Leguminosae. in Engelmann 

    (ed.): Natürliche Pflanzenfamilien. Vol. III, 3., 1891

 

Acacia seyal from Paul Hermann Wilhelm 

 Taubert's Leguminosae. in Engelmann 

     (ed.): Natürliche Pflanzenfamilien. Vol. III, 3., 1891

What is gum arabic?

Definition: 
Moroccan Arabic: meska harra المسكة الحرة
Gum arabic is used as a stabilizer, thickener and binder. A natural gum, it's actually the hardened sap of the Acacia senegal or Acacia seyal tree which is common to sub-Sahara Africa as well as Arabia, Egypt and West Asia.
   
Gum arabic, also known as gum acacia, chaar gund, char goond or meska, is a natural gum made of hardened sap taken from two species of the acacia tree; Acacia senegal and Acacia seyal. The gum is harvested commercially from wild trees throughout the Sahel from Senegal and Sudan to Somalia, although it has been historically cultivated in Arabia and West Asia. Gum arabic is a complex mixture of polysaccharides and glycoproteins that is used primarily in the food industry as a stabilizer. It is edible and has E number E414. Gum arabic is a key ingredient in traditional lithography and is used in printing, paint production, glue, cosmetics and various industrial applications, including viscosity control in inks and in textile industries, although less expensive materials compete with it for many of these roles. While gum arabic is now produced throughout the African Sahel, it is also still harvested and used in the Middle East. For example, Palestinians use the natural gum to make a chilled, sweetened, and flavored gelato-like dessert.

                            
                                    Gum Arabic resin ( Gum Acacia, Meska Harra )

Properties and structure of gum arabic:

Technically, gum arabic (acacia senegal) is classed in a group of substances called, oddly, arabinogalactan proteins. More descriptively, it is essentially a very complex polysaccharides, comprised mostly of galactose, arabinose, rhamnose, and glucuronic acid. There is also a very small amount of protein: 18 different amino acids have been identified in acacia senegal, although only four of them comprise more than 10% of the protein, and altogether these amino acids comprise only around 1-2% of the total gum; the other 98-99% is made of the aforementioned sugars.

Gum arabic readily dissolves in water to form highly concentrated solutions of relatively low viscosity, which is a consequence of the gum's highly branched very compact structure. Gum is heterogeneous in nature; at least three discrete components have been identified:

The first, which comprises the greatest part of the gum (~90%), has a molecular weight of about 250,000 and contains almost no amino acids. Analysis suggests that the structure of this component is globular and highly branched.

The second component, comprising around 10% of the total, has a molecular weight of 1,500,000 or so, contains about 10% protein, and is thought by most workers to have what they describe as a "wattle-blossom" structure, consisting of probably five globular lobes of carbohydrate, about 250,000 molecular weight each, which are attached to a common polypeptide chain. The predominant amino acids in this portion are hydroxyproline and serine.

The third component, comprising less than 1% of the total gum, contains 20-50% protein but is not degraded by proteolytic enzymes, suggesting that the protein is located deep in the center of the molecule, available neither to be attacked by enzymes nor to participate in cross linking. The molecular weight of this component is about 200,000 and it is also highly compact. The predominant amino acids in this fraction are aspartic, serine, leucine, and glycine.

Gum Species :

There are more than two dozen species of acacia in the Sudan, but the most important is the Acacia Senegal species. The two species defined for Gum Acacia and the proportion of the market they supply are:
1.    Acacia Senegal - 80%
2.    Acacia Seyal - 20%  

1. Acacia Senegal 

The Acacia Senegal tree is 4-7 m tall with a taproot up to 30 m in depth and a life span of about 25-30 years. The tree can fix nitrogen from the air and grows in poor, sandy, reddish soil, which is caused by the substantial amount of iron present. 65% of the world's supply of Gum Acacia comes from the Sudan.

Throughout the Sudanese province of Kordofan, there are orchards of Acacia Senegal (also called Acacia verek locally), and these are in a belt stretching eastward to the River Nile, and westward through the Province of Darfur. However, in some areas the trees are cultivated and tended in small gardens, and the gum collected from the cultivated tree is colloquially known as ' HASHAB GENIENA' (garden gum). One of the reasons why Kordofan Gum Acacia has an excellent quality is due to the limitation of botanical sources resulting in a uniform product. 90% of the Gum Acacia production in the Sudan is of this high quality.

2. Acacia Seyal
The other species of commercial importance is Acacia Seyal, which grows throughout the African gum belt. Known as Gum Tahla in Sudan and Acacia Grade 2 in Nigeria, Acacia seyal yields a gum, which is not as functional, being weaker in emulsification power due to its different chemical composition.
Several other species of Acacia exude gum, and before today’s segregation of species the gum from these trees was occasionally mixed with other gums. These include A. abyssinica, A. acaciaa, A. laeta, A. orfota, A. stenocaipa.

Gum Arabic benefits:

•    Multifunctional: good emulsifier, film-former, texturizer and low-viscosity water binder and bulking agent.
•    High source of fiber: contains no less than 85% soluble dietary fiber (dry basis)
•    High percentage purity: no additives; free from sediment and impurities; has extremely low bacterial counts
•    Fast hydration and ease of dispersion: available in prehydrated or agglomerated form.
"Natural" labeling: Gum arabic is not chemically modified and qualifies for "natural" labeling or "no artificial additives