Gum Arabic: Properties, Facts, and Importance

By Eman Abdallah Kamel

Gum Arabic has a long history. This article discusses the history, chemical composition, properties, and uses of gum Arabic.

What is gum arabic?

Gum Arabic is a mixture of sugar, protein, and multiple sugars. It is a source of the sugars arabinose and ribose. Gum Arabic is harvested from wild trees commercially throughout the coast, from Sudan, Senegal, and Mali to Somalia.

Acacia is a thorny shrub that grows best in a dry, sandy climate. Acacia trees are mostly found in North Africa, especially in Sudan. It is also found in Arabia, Australia, and India to a lesser extent.

There are two types of gum Arabic trees: Acacia Senegal and Acacia Sial. Acacia trees are among the tallest and fastest-growing trees in their habitat.

Globally, Sudan produces and exports the most gum arabic. With about 30% of the gum Arabic trade going to the United States, Europe accounts for about 20%. The confectionery industry is the largest use of gum arabic in Europe, while in the United States, it is widely used in the soft drink industry. Japan accounts for less than 10% of global trade. There are new markets in India, China, and South Korea.

Did You Know?

The acacia tree is a genus in the Mimosoideae subfamily of the pea family Fabaceae. There are about 170 species of acacia that are native to Africa.

Birds on an acacia tree, a wall painting from the tomb of Khnumhotep III. He was an ancient Egyptian high steward and vizier of the 12th Dynasty.
Image source: pinterest.com

A Brief History of Gum Arabic

In the Stone Age, acacia gum was used as a food in the desert and as a sticky substance in Africa for at least 70,000 years.

The ancient Egyptians used gum arabic in their inks, watercolors, and dyes. Gum Arabic was also a pigment binder for the paints used to make hieroglyphs. It was used to make mummy bandages adhere more quickly. It was also used in the manufacture of cosmetics and food.

From the fifties to the early nineties, Sudanese gum has been 80% of the global gum Arabic trade.

However, as a result of fluctuations from year to year, the general deterioration in Sudanese gum exports, the effects of drought (mid-seventies and eighties), political instability, and weak marketing procedures led to the emergence of other countries producing gum Arabic, such as Chad and Nigeria. As a result, Sudan’s share in the market has decreased over the past fifteen years globally to less than 50%.

Mali was one of the historical exporters of Gum Arabic, along with Senegal and Sudan, but the trade diminished in the second half of the twentieth century. Until the 1960s, Mali was producing more than 10,000 tonnes of raw gum Arabic per year. As a result of a combination of natural and political factors, Mali exported only 32 tonnes of raw gum per year by 1992. Mali has lost 82% of its vegetation since 1960. Approximately 450,000 hectares (1.1 million acres) were lost between 2001 and 2018 due to several factors, including forest fires and deforestation for fuel.

Chemical Structure of Gum Arabic.
researchgate.net

Chemical Composition

The chemical composition of gum Arabic is complex. The backbone of gum Arabic is composed of 1,3-linked β-D-galactopyranosyl units.

There are two to five 1,3-linked β-D-galactopyranosyl units on the side chains, linked by 1,6 links to the main chain.

Both the prime and the side chains consist of α-L-arabinose furanose, α-L-rhamnopyranosyl, β-D-glucopyranosyl, and 4-O-methyl-β-D-glucopyranose units.

Gum Arabic is made of high-molecular-weight polysaccharides and their magnesium, calcium, and potassium salts, which, on hydrolysis, yield three main fractions of polysaccharides and proteins, including arabinogalactan, arabinogalactan protein, and glycoprotein.

Did You Know?

Arabinogalactan protein is the most active component and is responsible for the emulsifying properties of gum arabic.

Gum Arabic. food navigator-usa.com

Properties

The physical properties of gum Arabic may vary depending on tree origin, age, and climate.
The color of premium-quality gum arabic is orange-brown, teardrop-shaped, and round. It has a vitreous appearance after crushing.
Gum Arabic has a high water solubility and a relatively low viscosity. The viscosity of gum Arabic solutions can be adjusted by adding acids or bases, as these change the macromolecule’s electrostatic charge.
Gum Arabic can be dissolved in water, forming a fluid solution with acidic properties (pH ~ 4.5). The resulting solution is colorless, tasteless, and does not easily interact with other chemical compounds.

Gum Arabic

Uses

Gum Arabic is used in textiles, ceramics, and lithography. In addition to cosmetics, paints, and paper.
It is also used in pastry and dairy.
Senegal gum is widely used in food applications, mainly due to its better emulsifying properties than seyal gum. Additionally, the solutions of A. senegal gum are generally less colorful than those of A. seyal gum. These characteristics explain the differences in the higher price of A. senegal gum compared to A. seyal in the international market.
Gum Arabic is used in essential oils and cola oils for soft drinks.
It is also used in frozen products, such as ice cream, as a stabilizing agent.

Future

The increase in acacia tree cultivation is considered an increase in gum Arabic production. Several projects have already been implemented to increase acacia cultivation.

Mali planted 1,250 hectares (3,090 acres) of Acacia Senegal in the Nara region, near Mauritania.

The agricultural financial company Déguessi Vert works with farmers and the Principal Agricultural Research Agency of Mali, along with the Institute for Rural Economy, on the farm, which also aims to develop health infrastructure and schools in the villages participating in the Mali Acacia project. This programme covers 6,000 hectares of acacia trees in different parts of the country.

Malian authorities also see growing acacia as an opportunity to reduce deforestation as part of the African Union’s Great Green Wall project. Mali is planning to plant thousands of hectares of acacia trees.

The Great Green Wall project will help to create more than 4,970 miles of vegetation that will help bind soil, reduce erosion, conserve water, and slow desert encroachment.

According to the Klorane Botanical Foundation, more than 80,000 palm trees have already been planted, and more than 45,000 hectares (110,000 acres) of the desert have been regreened with various trees, including Acacia senegal and Acacia seyal.

Did You Know?

The Great Green Wall symbolizes hope against desertification. The African Union launched this initiative in 2007 to restore Africa’s degraded landscapes, hoping to improve the lives of millions of people in one of the world’s poorest regions, the Sahel.

Sources

About the author: Eman is a writer and an engineer. She is interested in writing about plants and their facts.

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