Gum Tragacanth

Definition:

Astralgus gummifer

Astralgus

Leguminosae

Astralgus gummifer

Table 1: Gum Tragacanth Properties
Property	Description
Solubility in Cold Water	Two components: one which swells in water and a water-soluble component
Funcionality	• acid stable and resistant • bifunctional emulsifier • pseudoplastic • film former • bodying agent • adhesive • suspending agent • thickener

Table 2: A Typical Product Specification of a Commercial Gum Tragacanth
Property	Description
Appearance	Off white to creamy coloured fine powder
Loss on drying	12% maximum
Ash	3% maximum
Acid insoluble ash	0.3% maximum/TD>
Viscosity 1% in water	800 ± 150 cps2
Particle size	90% minimum pass 150 mesh BSS
Heavy metals: Pb	10% maximum
Heavy metal: As:	3% maximum
Microbiology	Salmonella/E.Coli absent

Table 3: Gum Tragacanth Applications

Oil and flavour emulsions
Soft drinks
Confectionary and icings
Bakery emulsions and fillings
Ice creams, ices and sherbets
Pourable salad dressings and sauces
Pharmaceuticals and cosmetics

Composition:

Chemically gum tragacanth consists of two fractions. One fraction is termed Tragacanthic acid or Bassorin, which represents 60– 70% of the total gum. It is insoluble in water but has the capacity to swell and form a gel. Another smaller fraction termed tragacanthin is soluble in water to give a colloidal hydrosol solution. After acid hydrolysis the major components are: D-galacturonic acid and D-galactose, L-fucose, D-xylose, L-arabinose; L-rhamnose. D-galacturonic acid is also a major component of tragacanthic acid.

For Further details see Handbook of Food Hydrocolloids (2000); Editors Glyn O. Phillips and Peter A. Williams, Woodhead Publishing pp 231 by W.Weiping.

Regulatory status

Gum tragacanth is classified as “generally regarded as safe” (GRAS) within the USA. It is also classified as “acceptable daily intake (ADI) not specified”, which is the highest category of safety evaluation by the Joint WHO/FAO Expert Committee for Food Additives (JECFA) and has the number E 413 in the list of food additives approved by the Scientific Committee for Food of the European Community.