Arabic gum

Overview

Gum arabic[GA] is a branched-chain, complex polysaccharide, either neutral or slightly acidic, found as a mixed calcium, magnesium and potassium salt of a polysaccharidic acid^[1-3]. Its backbone is composed of 1,3-linked b-D-galactopyranosyl units. The side chains are composed of two to five 1,3-linked b-D-galactopyranosyl units, joined to the main chain by 1,6-linkages.

Figure 1 Arabic gum[piece and powder].

Applications

GA has wide industrial uses as a stabilizer, thickening agent and emulsifier, mainly in the food industry[e.g. in soft drinks syrup, gummy candies and marshmallows], but also in the textile, pottery, lithography, cosmetics and pharmaceutical industries^[3].
In folk medicine, GA has been reported to be used internally for the treatment of inflammation of the intestinal mucosa, and externally to cover inflamed surfaces^[4]. Some recent reports have claimed that GA possesses anti-oxidant, nephroprotectant and other effects^[4-6]. Clinically, it has been tried in patients with chronic renal failure, and it was claimed that it helps reduce urea and creatinine plasma concentrations and reduces the need for dialysis from 3 to 2 times per week^[7].

Biological and pharmacological effects

Lipid mechanism
GA increased cholesterol biosynthesis in rats fed a cholesterol-containing diet, but had no effect in rats on a cholesterol-free diet^[8]. Ross et al.^[9] and Sharma^[10] reported reductions of total serum cholesterol by 6% and 10.4%, respectively when subjects received 25 g/day and 30 g/day of GA for periods of 21 and 30 days. The decrease was confined to LDL and VLDL cholesterol only, with no effect on HDL and triglycerides.
Blood glucose level
Mixtures of different types of gum have been shown to inhibit glucose movement in vitro, and lower postprandial blood glucose and plasma insulin in human subjects when incorporated in a drink containing 50 g glucose^[11,12].
Gastrointestinal tract
GA can improve small intestinal absorption of water as well as electrolytes^[13,14]. Various mechanism[s] have been proposed to account for the proabsorptive effects of GA on intestinal water and electrolytes under normal conditions and more so in conditions of diarrheal illness^[15]. GA is a soluble fiber with moderate emulsifying properties^[16] that may result in greater accessibility of electrolytes and associated water to the microvillous membrane. This was probably reflected in the increased lumen-to-serosa water influx noted with GA administration in the chronic osmotic-secretory diarrhea model^[14].
Tooth mineralization
It has been shown, using histopathological methods, that GA has the ability to enhance remineralization^[17], probably by supporting other remineralization activities. This supporting role was ascribed to the rich content of Ca2+, Mg2+, and K+ salts of polysaccharides in GA, and to the effect of the gum on the metabolism of Ca2+ and possibly phosphate.

Adverse effects and Toxicity

No significant adverse or toxic actions have been associated with the use of GA.

References

1. Anderson, D.M.W., Stoddart, J.F., 1996. 2, 104–114.
2. Islam, A.M., Phillips, G.O., Sljivo, M.J., Williams, P.A., 1997. Food Hydrocoll. 11, 493–505.
3. Verbeken, D., Dierckx, S., Dewettinck, K., 2003. Appl. Microbiol. Biotechnol. 63, 10–21.
4. Gamal el-din, A.M., Mostafa, A.M., Al-Shabanah, O.A., Al-Bekairi, A.M., Nagi, M.N., 2003. Pharmacol. Res. 48, 631–635.
5. Rehman, K., Wingertzahn, M.A., Harper, R.G., Wapnir, R.A., 2001. J. Pediatr. Gastroenterol. Nutr. 32, 529–533.
6. Ali, A.A., Ali, K.E., Fadlalla, A., Khalid, K.E., 2008. Nat. Prod. Res. 22, 12–21.
7. Suliman, S.M., Hamdouk, M.I., Elfaki, M.B., 2000. G.A. fiber as a supplement to low protein diet in chronic renal failure patients. In: Sudan Association of Physicians, 17th Conference, Friendship Hall, Khartoum, Sudan, 21–23 March.
8. Kelley, J.J., Tsai, A., 1978. J. Nutr. 108, 630–639.
9. Ross, A.H., Eastwood, M.A., Brydon, W.G., Anderson, J.R., Anderson, D.M., 1983. Am. J. Clin. Nutr. 37, 368–375.
10. Sharma, R.D., 1985. Nutr. Res., 1321–1326.
11. Edwards, C.A., Blackburn, N.A., Craigen, L., Davison, P., Tomlin, J., Sugden, K., Johnson, I.T., 1987. Am. J. Clin. Nutr. 46, 72–77.
12. Torsdottir, I., Alpsten, M., Andersson, H., Einarsson, S., 1989. J. Nutr. 119, 1925–1931
13. Codipilly, C.N., Wapnir, R.A., 2004. Dig. Dis. Sci. 49, 1473–1478.
14. Wapnir, R.A., Wingertzahn, M.A., Moyse, J., Teichberg, S., 1997. Gastroenterology 112, 1979–1985.
15. Codipilly, C.N., Teichberg, S., Wapnir, R.A., 2006. J. Am. Coll. Nutr. 25, 307–312.
16. Phillips, G.O., 1998. Food Addit. Contam. 15, 251–264.
17. Onishi, T., Umemura, S., Yanagawa, M., Matsumura, M., Sasaki, Y., Ogasawara, T., Ooshima, T., 2008. Arch. Oral. Biol. 53, 257–260.

Description

Acacia gum is an odourless white to yellow-white powder. It is soluble in water and incompatible with alcohol and oxidising agents and precipitates. It gels on addition of solutions of ferric salts, borax, lead subacetate, alcohol, sodium silicate, gelatin, and ammoniated tincture of guaiac. It is non-toxic and non-hazardous. It is a water-soluble gum from several species of the acacia tree, especially Acacia senegal and A. arabica, and used in the manufacture of adhesives and ink and as a binding medium for marbling colours. Gum arabic is also known as gum acacia and is a natural gum made of hardened sap taken from two species of the Acacia tree – Acacia senegal and Acacia seyal. Gum arabic is a natural product of the Acacia senegal tree, occurring as an exudate from the trunks and branches. It is used primarily in the food industry as a stabiliser but has had more varied uses. It is normally collected by hand when dried, when it resembles a hard, amber-like resin normally referred to as ‘tears’. Gum arabic is widely used in the food industry as an emulsifier, thickener, and flavouring and thickening agent. It is employed as a soothing agent in inflammatory conditions of the respiratory, digestive, and urinary tracts and is useful in diarrhoea and dysentery. It exerts a soothing influence upon all the surfaces with which it comes in contact. Gum acacia is an ingredient of all the official Trochisci and various syrups, pastes, and pastilles or jujubes. During the time of the gum harvest, the Moors of the desert are said to live almost entirely on it, and it has been proved that 6 oz. is sufficient to support an adult for 24 h. Gum acacia is highly nutritious, is a mixture of saccharides and glycoproteins, and provides the properties of a glue and binder suitable for human edibility. In many cases of disease, it is considered that a solution of gum arabic may for a time constitute the exclusive drink and food of the patient. Gum arabic reduces the surface tension of liquids, which leads to increased fizzing in carbonated drinks.

Chemical Properties

Acacia is available as white or yellowish-white thin flakes, spheroidal tears, granules, powder, or spray-dried powder. It is odorless and has a bland taste.

Chemical Properties

white to yellow-white powder

Chemical Properties

Acacia gum is a white to yellow-white odorless powder. It is soluble in water and incom- patible with alcohol, oxidizing agents, and precipitates or forms jellies on addition of solutions of ferric salts, borax, lead subacetate, alcohol, sodium silicate, gelatin, ammoni- ated tincture of guaiac. It is non-toxic and non-hazardous. A water-soluble gum from several species of the acacia tree, especially Acacia senegal and A. Arabica , it is used in the manufacture of adhesives and ink, and as a binding medium for marbling colors. Gum arabic, also known as gum acacia, chaar gund, or char goond, is a natural gum made of hardened sap taken from two species of the acacia tree— A. senegal and A. seyal . Gum arabic is a natural product of the A. senegal tree, occurring as an exudate from the trunks and branches. It is used primarily in the food industry as a stabilizer, but has had more varied uses. It is normally collected by hand when dried, when it resembles a hard, amber-like resin normally referred to as “tears.” Gum arabic is widely used in the food industry, as an emulsifi er, thickener, and fl avor enhancer. It is employed as a soothing agent in infl ammatory conditions of the respiratory, digestive, and urinary tract, and is useful in diarrhea and dysentery. It exerts a soothing infl uence on all the surfaces with which it comes in contact. Gum acacia is an ingredient of all the offi cial Trochisci, and various syrups, pastes, and pastilles or jujubes. During the time of the gum harvest, the Moors of the desert are said to live almost entirely on it, and it has been proved that 6 oz is suffi cient to support an adult for 24 h. Gum acacia is a mixture of saccharides and glycoproteins, is highly nutritious, and provides the properties of a glue, and a binder suitable for human consumption. In many cases of disease, it is considered that a solu- tion of gum arabic may, for a time,constitute the exclusive drink and food of the patient. Gum arabic reduces the surface tension of liquids, which leads to increased fi zzing in carbonated drinks.

Chemical Properties

Arabic.or.acacia.gum.is.the.dried.exudate.obtained.from.the.stems.and.branches.of.Acacia senegal (L.).Willd.or.of. related.species.of.Acacia..Injured.trees.exude.gum.Arabic;.heat,.poor.nutrition.and.drought.stimulate.its.production..Most.of.the.gum. Arabic.production.is.from.wild.trees,.but.some.from.privately.owned.and.cultivated.gardens.are.tapped.and.collected.on.a.systematic. basis.
The.gum.called.Hashab.geneina.(garden.gum).is.the.cleanest.and.lightest.grade.and.is.most.preferred.for.the.U.S..market..The.wild. gum.(called.Hashab.wady).is.collected.on.a.part-time.basis.in.the.dry.season,.from.October.to.May.or.June,.by.natives.whose.main. occupation.is.usually.farming..After.gathering,.it.is.taken.to.central.collecting.stations.where.it.is.auctioned.under.government.supervision,.graded.by.hand.and.dried.before.exporting.to.gum.suppliers.in.all.parts.of.the.world..Then.it.is.resorted,.ground,.processed. and.graded.to.various.specifications
Clear,.white.(sun-bleached).spheroidal.tears,.up.to.32.mm.in.diameter,.also.occur.as.flakes..Chemically,.gum.Arabic.is.a.neutral.or. slightly.acid.salt.of.a.complex.polysaccharide.containing.calcium,.magnesium.and.potassium.cations..Its.most.distinguishing.property.among.the.natural.gums.is.its.extreme.solubility.in.water..Solutions.of.over.50%.concentration.may.be.prepared..Gum.Arabic. is.best.described.as.“heteropolymolecular,”.that.is,.a.polymer.system.having.either.a.variation.in.monomer.(galactose,.arabinose,. rhamnose,.glucuronic.acid.and.4-O-methylgucuronic.acid).composition.and/or.variation.in.the.mode.of.linking.and.branching.of.the. monomer.units,.in.addition.to.a.distribution.in.molecular.weight.
Major.uses.of.gum.Arabic.in.foods.are.as.a.fixative.for.flavors,.a.foam.stabilizer.in.beverages,.an.adhesive.for.icings.and.toppings,. and.an.emulsifier.and.stabilizer.in.confectionary.and.ice.cream.It.is.also.widely.used.in.the.pharmaceutical,.cosmetic,.paper,.textile,. paint,ink.and.lithography.industries.

Uses

As mucilage, excipient for tablets, size, emulsifier, thickener, also in candy, other foods; as colloidal stabilizer. In the manufacture of spray-dried "fixed" flavorsstable, powdered flavors used in packaged dry-mix products (puddings, desserts, cake mixes) where flavor stability and long shelf life are important.

Uses

acacia (Acacia senegal)(acacia gum; black catechu; gum acacia; gum Arabic) is commonly used in traditional remedies as a soothing and anti-inflammatory agent. It is also used as a vegetable gum for product thickening. In extract form, acacia is recommended for dry, sensitive, or delicate skin. Acacia is the dried gummy sap from the stems and branches of various species of the African acacia tree. It may cause skin rashes in cases of allergy.

Uses

A gum obtained from breaks or wounds in the bark of acacia trees. It dissolves in hot or cold water forming clear solutions which can be up to 50% gum acacia. The solubility in water increases with temperature. It is used in confectionary glazes to retard or prevent sugar crystallization and acts as an emulsifier to prevent fat from forming an oxidizable, greasy film. It functions as a flavor fixative in spray-drying to form a thin film around the flavor particle. It also functions as an emulsifier in flavor emulsions, as a cloud agent in beverages, and as a form stabilizer. It is also termed acacia.

Production Methods

Acacia is the dried gummy exudate obtained from the stems and branches of Acacia senegal (Linné ) Willdenow or other related species of Acacia (Fam. Leguminosae) that grow mainly in the Sudan and Senegal regions of Africa.
The bark of the tree is incised and the exudate allowed to dry on the bark. The dried exudate is then collected, processed to remove bark, sand, and other particulate matter, and graded. Various acacia grades differing in particle size and other physical properties are thus obtained. A spray-dried powder is also commercially available.

Definition

The dried, water-soluble exudate from the stems of Acacia senegal or related species.

Taste threshold values

Absolute;.taste.characteristics.at.15.ppm:.spicy.sweet,.fruity.and.honey.with.a.woody,.herbal.nuance

General Description

White powder.

Air & Water Reactions

Water soluble. Aqueous solution is acid to litmus.

Reactivity Profile

Arabic gum reacts with strong oxidizing agents. Arabic gum precipitates out of solution or jellies upon addition of solutions of ferric salts, borax, basic lead acetate, alcohol, sodium silicate, gelatin or ammoniated tincture of guaiac.

Health Hazard

Exposures to gum arabica dust produce a weak allergen reaction. Prolonged periods of dust inhalation may cause allergic respiratory reaction, headache, coughing, dizziness, dyspnea, respiratory symptoms such as asthma, watery nose and eyes, cough, wheezing, nausea, vomiting, dyspnea, and urticaria. Hives, eczema, and swelling may also occur. Ingestion and inhalation of gum acacia is considered non-toxic, but sensitive individuals may develop symptoms of mild toxicity.

Fire Hazard

Flash point data for Arabic gum are not available; however, Arabic gum is probably combustible.

Pharmaceutical Applications

Acacia is mainly used in oral and topical pharmaceutical formulations as a suspending and emulsifying agent, often in combination with tragacanth. It is also used in the preparation of pastilles and lozenges, and as a tablet binder, although if used incautiously it can produce tablets with a prolonged disintegration time. Acacia has also been evaluated as a bioadhesive; and has been used in novel tablet formulations,and modified release tablets.
Acacia is also used in cosmetics, confectionery, food products, and spray-dried flavors.

Biochem/physiol Actions

Gum arabic (GA) is reported to be a strong anti-oxidant and has shown protection against nephrotoxicity in mice by the generation of free radicals. GA also reduced the blood glucose concentration by initiating the release of insulin from the pancreatic β cells. It has hypolipidemic effect by increasing fecal bile acid and modification of lipid digestion. It is a potential therapeutic agent in hepatic and renal failures. It contains enzymes like oxidases, pectinases and peroxidases that act against microbes that cause tooth decay. Gum arabic is implicated in adverse effects like suppression of macrophage activation.

Safety Profile

Very low toxicity by ingestion.Inhalation or ingestion has produced hives, eczema, andangiodema. Experimental reproductive effects. A severeeye irritant. A weak allergen. Mutation data reported.Combustible. When heated to decomposition it emitsacrid

Safety

Acacia is used in cosmetics, foods, and oral and topical pharmaceutical formulations. Although it is generally regarded as an essentially nontoxic material, there have been a limited number of reports of hypersensitivity to acacia after inhalation or ingestion.Severe anaphylactic reactions have occurred following the parenteral administration of acacia and it is now no longer used for this purpose.
The WHO has not set an acceptable daily intake for acacia as a food additive because the levels necessary to achieve a desired effect were not considered to represent a hazard to health.
LD₅₀ (hamster, oral): >18 g/kg
LD₅₀ (mouse, oral): >16 g/kg
LD₅₀ (rabbit, oral): 8.0 g/kg
LD₅₀ (rat, oral): >16 g/kg

storage

Aqueous solutions are subject to bacterial or enzymatic degradation but may be preserved by initially boiling the solution for a short time to inactivate any enzymes present; microwave irradiation can also be used. Aqueous solutions may also be preserved by the addition of an antimicrobial preservative such as 0.1% w/v benzoic acid, 0.1% w/v sodium benzoate, or a mixture of 0.17% w/v methylparaben and 0.03% propylparaben. Powdered acacia should be stored in an airtight container in a cool, dry place.

Incompatibilities

amidopyrine, apomorphine, cresol, ethanol (95%), ferric salts, morphine, phenol, physostigmine, tannins, thymol, and vanillin.
An oxidizing enzyme present in acacia may affect preparations containing easily oxidizable substances. However, the enzyme may be inactivated by heating at 100℃ for a short time.
Many salts reduce the viscosity of aqueous acacia solutions, while trivalent salts may initiate coagulation. Aqueous solutions carry a negative charge and will form coacervates with gelatin and other substances. In the preparation of emulsions, solutions of acacia are incompatible with soaps.

Regulatory Status

GRAS listed. Accepted for use in Europe as a food additive. Included in the FDA Inactive Ingredients Database (oral preparations and buccal or sublingual tablets). Included in the Canadian List of Acceptable Non-medicinal Ingredients. Included in nonparenteral medicines licensed in the UK.