How Is Gum Arabic Produced and Why Is It Important?
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.
FAQs on Gum Arabic: Definition, Properties & Applications
1. What is Gum Arabic and from which natural source is it obtained?
Gum Arabic, also known as acacia gum, is a natural gum consisting of the hardened sap of two species of the Acacia tree: Senegalia senegal and Vachellia seyal. It is a complex mixture of glycoproteins and polysaccharides, making it a type of natural hydrocolloid. It is harvested commercially from wild trees, primarily in Sudan and across the Sahel region of Africa.
2. What are the key chemical and physical properties of Gum Arabic?
Gum Arabic has several distinct properties that make it useful in various applications:
High Solubility: It dissolves readily in both cold and hot water to form a viscous, but not gummy, solution.
Low Viscosity: Compared to other gums, it produces solutions of relatively low viscosity, even at high concentrations.
Tasteless and Odourless: It is essentially colourless, tasteless, and odourless, making it an ideal additive that does not alter the sensory profile of food products.
Chemical Nature: It is a mildly acidic to neutral salt of a complex polysaccharide (arabinogalactan). Chemically, it is composed of sugars like arabinose, galactose, rhamnose, and glucuronic acid.
3. What are the most common industrial applications of Gum Arabic?
Gum Arabic is a versatile substance used across many industries. Its primary applications include:
Food Industry: Used as a stabilizer, emulsifier, and thickening agent in products like soft drinks, icings, chewing gum, and candies. It prevents sugar crystallization and keeps fats uniformly mixed.
Pharmaceuticals: Used as a binder in tablets, a suspending agent in syrups, and an emulsifier in lotions.
Art and Lithography: It is a traditional binder in watercolour paints and is used in printing for its protective, hydrophilic properties.
Other Industries: It is also found in cosmetics, adhesives, and ink production.
4. How is Gum Arabic classified as a biomolecule?
Gum Arabic is classified as a complex polysaccharide. Specifically, it is an arabinogalactan-protein, which is a branched-chain polymer. The backbone consists of galactose units, with side chains containing arabinose, rhamnose, and glucuronic acid. The presence of these sugar units and amino acids makes it a naturally occurring biopolymer, placing it in the broad category of carbohydrates.
5. Why is Gum Arabic considered an excellent emulsifier, especially in beverages?
Gum Arabic's effectiveness as an emulsifier stems from its unique molecular structure. It is an amphiphilic molecule, meaning it has both a water-loving (hydrophilic) polysaccharide part and an oil-loving (lipophilic) protein part. The hydrophilic portion dissolves in the water phase of a beverage, while the lipophilic portion attaches to the oil droplets (like flavouring oils). This dual action allows Gum Arabic to form a stable protective layer around the oil droplets, preventing them from coalescing and separating from the water, thus creating a stable emulsion.
6. What makes Gum Arabic highly soluble in water, unlike many other large polysaccharides?
The high solubility of Gum Arabic is due to its highly branched, compact, and globular structure. Unlike long, linear polysaccharides like cellulose which can easily align and form strong intermolecular hydrogen bonds, the intricate branching of Gum Arabic prevents such tight packing. This open structure allows water molecules to easily penetrate and hydrate the individual polymer chains, leading to its remarkable solubility in water.
7. Are there any known health benefits or side effects of consuming Gum Arabic?
Yes, Gum Arabic is generally recognized as safe for consumption and is valued for its health benefits. It is a rich source of soluble dietary fibre, which can aid in digestion, promote satiety (a feeling of fullness), and act as a prebiotic to support healthy gut bacteria. However, for some individuals, consuming very large amounts may cause mild side effects like gas, bloating, or loose stools, which are common with high fibre intake.
8. How does Gum Arabic chemically differ from other common gums like Xanthan Gum?
While both are hydrocolloids used as food additives, Gum Arabic and Xanthan Gum differ significantly in their origin and structure:
Source: Gum Arabic is a natural plant exudate from the Acacia tree. Xanthan Gum is produced through the bacterial fermentation of sugar by Xanthomonas campestris.
Structure: Gum Arabic is a complex, branched arabinogalactan-protein. Xanthan Gum has a more regular, cellulose-like backbone with trisaccharide side chains.
Functionality: Gum Arabic is an excellent emulsifier but a poor thickener. Xanthan Gum is an exceptionally strong thickening and gelling agent but is less effective as an emulsifier compared to Gum Arabic.
