Gum arabic is a natural
gum originally consisting of the hardened sap of two species of
the Acacia tree, Senegalia
senegal and Vachellia seyal. Senegalia senegal
(also known as Acacia senegal) is a small thorny
deciduous tree from the genus Senegalia,
which is known by several common names, including gum acacia, gum
arabic tree, Sudan gum and Sudan gum arabic. In parts of
India, it is known as Kher or Khor. It is native to semi-desert
regions of Sub-Saharan Africa, as well as Oman, Pakistan, and
west coastal India.
It grows to a height of 5–12 metres (16-40'), with a trunk up to 30 cm
(1') in diameter. Sudan is the source of the world's highest quality gum arabic,
known locally as hashab gum in contrast to the related, but inferior,
gum arabic from Red acacia or talah gum.
The term
"gum arabic" does not legally indicate a particular botanical source,
however. The gum is
harvested commercially from wild trees, mostly in Sudan (80%) and
throughout the Sahel,
from Senegal
to Somalia. The
gum is drained from cuts in the bark, and an individual tree will yield 200 to
300 grams (7 to 10 oz). The name "gum Arabic" (al-samgh al-'arabi)
was used in the Middle East at least as early as the 9th century. Gum arabic first
found its way to Europe via Arabic ports, so retained its name.
Gum arabic is
a complex mixture
of glycoproteins
and polysaccharides, predominantly polymers of arabinose
and galactose.
It is soluble in water, edible, and used primarily in the food
industry and soft-drink industry as a stabilizer, with E number
E414 (I414 in the US). Gum arabic is a key ingredient in traditional lithography
and is used in printing,
paints, glues, cosmetics,
and various industrial applications, including viscosity
control in inks and
in textile industries, though less expensive materials compete with it for many
of these roles.
Health benefits
Gum arabic is a rich source of dietary fibers and in addition to its widespread use in food and pharmaceutical industries as a safe thickener, emulsifier, and stabilizer, it also possesses a broad range of health benefits that have been evidently proved through several in vitro and in vivo studies. Gum arabic is not degraded in the stomach but fermented in the large intestine into a number of short chain fatty acids. It is regarded as a prebiotic that enhances the growth and proliferation of the beneficial intestinal microbiota and therefore its intake is associated with many useful health effects. These health benefits include:
- Improved absorption of calcium from the gastrointestinal tract
- Anti-diabetic
- Anti-obesity (gum arabic lowers the body mass index and body fat percentage)
- Lipid lowering potential (gum arabic decreases total cholesterol, LDL, and triglyceride)
- Antioxidant activities
- Kidney and liver support
- Immune function via modulating the release of some inflammatory mediators
- Prebiotic improving the intestinal barrier function, preventing colon cancer, and alleviating symptoms of irritable bowel diseases
- In rats, a protective effect on the intestine against the adverse actions of the NSAID drug meloxicam
Various Uses
Gum
arabic's mixture
of polysaccharides and glycoproteins gives it the properties of a glue and
binder that is edible by humans. Other substances have replaced it where toxicity is
not an issue, as the proportions of the various chemicals in gum arabic vary
widely and make it unpredictable. Still, it remains an important ingredient in soft drink
syrup and
"hard" gummy candies such as gumdrops, marshmallows,
and M&M's
chocolate candies. For artists, it is the traditional binder
in watercolor
paint and in
photography for gum printing, and it is used as a binder in pyrotechnic
compositions. Pharmaceutical drugs and cosmetics
also use the gum as a binder, emulsifier, and suspending agent or
viscosity-increasing agent.
It
is an important ingredient in shoe
polish, and can be used in making homemade incense cones. It is also used
as a lickable adhesive,
for example on postage stamps, envelopes,
and cigarette papers. Lithographic printers employ it
to keep the non-image areas of the plate receptive to water. This treatment
also helps to stop oxidation of aluminium printing
plates in the interval between processing of the plate and its use on a printing
press.
Production
While
gum arabic has been harvested in Arabia, Sudan, and West Asia since antiquity, sub-Saharan acacia gum has a
long history as a prized export. The gum exported came from the band of acacia
trees that once covered much of the Sahel region, the southern littoral of the Sahara
Desert that runs from the Atlantic
Ocean to the Red
Sea. Today, the main populations of gum-producing Acacia species are
found in Mauritania,
Senegal, Mali, Burkina
Faso, Niger, Nigeria, Chad, Cameroon,
Sudan, Eritrea,
Somalia, Ethiopia, Kenya, and Tanzania. Acacia
is tapped for gum by stripping bits off the bark, from which gum then exudes.
Traditionally harvested by seminomadic desert pastoralists in the course of
their transhumance
cycle, acacia gum remains a main export of several African nations, including
Mauritania, Niger, Chad, and Sudan. In Sudan hundreds of thousands of Sudanese
people are dependent on gum arabic for their livelihoods. After market reforms
total world gum arabic Sudan’s exports are today (2019) estimated at 160,000
tonnes, the production of gum arabic is heavily controlled by the Sudanese
government.
Desert locust plagues and potential upsurges swarm invasions
The
desert locust (Schistocerca gregaria) is a species of locust, a
periodically swarming, short-horned grasshopper in the family Acrididae.
They are found primarily in the deserts and dry areas of northern and eastern
Africa, Arabia, and southwest Asia.
During
plague years, desert locusts can cause widespread damage to crops, as they are
highly mobile and feed on large quantities of any kind of green vegetation,
including crops, pasture, and fodder. A typical swarm can be made up of 150 million
locusts per square kilometre (390,000,000 per square mile) and fly in the
direction of the prevailing wind up to 150 kilometres (93 mi) in one day.
Even a very small, 1-square-kilometre (0.39 sq mi) locust swarm can
eat the same amount of food in a day as about 35,000 people. They have two to
five generations per year. The desert locust risk increases with a
one-to-two-year continuum of favourable weather (greater frequency of rains)
and habitats that support population increases leading to upsurges and plagues.
The locust can live between 3 and 6 months, and a 10- to 16-fold increase in
locust numbers occurs from one generation to the next.
Desert
locusts consume an estimated equivalent of their body weight (2 g
(0.07 oz)) each day in green vegetation. They are polyphagous and feed on leaves, shoots,
flowers, fruit, seeds, stems, and bark. Nearly all crops and noncrop plants are
eaten, including pearl millet, maize, sorghum, barley, rice, pasture grasses,
sugarcane,
cotton, fruit
trees, date
palms, banana plants, vegetables, and weeds.
The
desert locust is a difficult pest to control, and control measures are further
compounded by the large and often remote areas (16–30 million square
kilometres (6.2–11.6 million square miles)) where locusts can be found.
Undeveloped basic infrastructure in some affected countries, limited
resources for locust monitoring and control, and political turmoil within and
between affected countries further reduce the capacity of a country to
undertake the necessary monitoring and control activities.
In
May 2018, Cyclone Mekunu brought unprecedented rainfall to the
Empty
Quarter of the Arabian Peninsula that was followed by Cyclone
Luban that brought heavy rains again to the same area in October. This
allowed conditions to be favourable for three generations of breeding, which
caused an estimated 8,000-fold increase in Desert Locust numbers that went
unchecked because the area was so remote it could not be accessed by national
locust teams.
