Gum Arabic in Chemistry Structure Properties and Applications

What is Gum Arabic?

Gum arabic, also called gum acacia, is a tree exudate obtained from the Acacia Senegal branches and stems.

Gum arabic majorly comprises high molecular weight polysaccharides including their calcium, magnesium, and potassium salts, that of hydrolysis, which yields arabinose, galactose, rhamnose, and glucuronic acid. It is a purely vegetable product and a harmless edible biopolymer. Sometimes, Gum Arabic from Acacia Senegal is also referred to as Talha.

Other names of gum arabic are gum acacia, acacia gum, Arabic gum, Indian guma, acacia, and Senegal gum. The term “gum arabic” was derived as this gum was shipped to Europe from Arabian ports in former times. Although the term “Arabic” deserves to be capitalized, yet “gum arabic” is considered as a predominant spelling.

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Gum Arabic Structure

The structure of gum arabic is given below.

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Properties of Gum Arabic

Let us look at some properties of Gum Arabic.

Physical Properties of Gum Arabic

The physical properties of gum arabic are tabulated below.

Chemical Properties of Gum Arabic

Production of Gum Arabic

While gum arabic is harvested in Sudan, West Asia, and Arabia since ancient times, the sub-Saharan acacia gum is considered as a prized export. The exported gum has come from the acacia trees band that once covered most of the Sahel region, the Sahara Desert’s southern littoral, running from the Atlantic Ocean to the Red Sea. 

Now, we can find the main populations of gum-producing Acacia species in Senegal, Mauritania, Mali, Nigeria, Chad, Somalia, Ethiopia, Tanzania, and Kenya. Acacia is tapped for gum arabic by stripping bits off the bark, where the gum exudes. 

Acacia gum remains the main export of several African nations, which is traditionally harvested by the seminomadic desert pastoralists in transhumance cycle course, including Niger, Sudan, and Chad. As of 2019, a total world gum arabic exports have estimated at 160,000 tonnes, having recovered from the 1987–1989; 2003–2005 crises caused by the destruction of trees by the locust desert.

Functions of Gum Arabic

Let us discuss some industries where gum arabic is used.

Photography

The process of historical gum bichromate photography uses gum arabic, which is mixed with potassium dichromate or ammonium and a pigment to create a coloured photographic emulsion, becomes relatively insoluble in the water upon exposure to ultraviolet light. Also, acacia gum binds the pigments permanently onto the paper in the final print.

Printmaking

Gum arabic can be used to protect and etch an image in lithographic processes, both from aluminum plates and traditional stones. In the lithography method, gum by itself can be used to etch very light tones, like those made with a number-five crayon. Nitric acid, tannic acid, or phosphoric acid is added in different concentrations to the acacia gum in etching the darker tones up to dark blacks. 

The process of etching also creates a gum adsorb layer within the matrix that causes to attract water by ensuring the oil-based ink is not sticky in those areas. The gum is also important in the paper lithography process, which is printed from an image created by a photocopier or laser printer.

Fuel Charcoal

Gum arabic can also be used as a binding agent in fuel charcoal making. Charcoal, which is made from the plant of taifa, is powdery, and thus to form charcoal cakes, the gum arabic is mixed with this powder and allowed to dry. Fuel charcoal, which is made from the gum arabic and taifa plant, is burnt in the kitchen in the cooking process of food in Senegal and some other African countries.

Uses of Gum Arabic

Some of the uses of Gum Arabic are listed below.

• The gum usage produces a more transparent effect than the glair, which is why the colour tends to be laid more thinly and appear darker and richer.

• Used more generously compared to glair, if a little amount of honey or sugar is added to keep it from becoming brittle.

• In brewing, gum arabic can be used as an agent to promote foam adhesion to glass and as a foam stabilizer.

• Gum arabic can be used as a basic ingredient of familiar foods like marshmallows, chewing gum, and licorice.

• Professional bartenders widely use gum or Gum syrup to prepare a few cocktails. These are essentially prepared with sugar water and addition of gum arabic for a pleasing taste.

• It is also used as a clarity stabilizer in the chemical treatment of wines.

Did You Know?

• Why is Gum Arabic Named So?

Gum arabic can be defined as a complex mixture of polysaccharides and glycoproteins. It is also the original source of arabinose sugars and ribose. Primarily, gum arabic is used in the food industry as a stabilizer.

• What are the Side Effects of Gum Arabic?

The side effects of gum arabic include allergic reactions, adverse effects in clinical trials, which include early morning nausea, unpleasant mouth sensation, bloating, and moderate diarrhoea.