Gum karaya

It is the dried exudate from the tree, Sterculia urens, tall bushy tree, native to India, where it grows in forests of the eastern and central mountains.  

Chemically, karaya is a complex, particular acetylated polysaccharide with an extremely high molecular weight, consisting of L-rhamnose, D-galactose, and D-galacturonic acid.

Food grade gum is usually a white to pinkish-gray powder. The gum has a high acetyl content and has a tendency of splitting off free acetic acid on aging, the rate of splitting depending on temperature, humidity and particle size.

Gum karaya absorbs water to form viscous colloidal sols. The particle size of the powder determines the types of dispersion.

Gum karaya is the least soluble gum exudate; it is used in foods as a thickening and suspending agent and as a stabilizer in salad dressing, ice cream, sherbets and frozen desserts, in which prevents the formation of large ice crystals.

Gum karaya is also used in cheese spread, sausages, and bakery products sometimes in combination with carrageenan.

Other usages of gum karaya are:
*protective colloid: stabilizer, viscosity control agent, thickener, emulsifier in cosmetics, pharmaceuticals;
*Thickener for textile dyes
*Binder for pulp in the preparation of long fibered, lightweight papers
*Textile coating, denture adhesive, binder in paper manufacturing
*Pharmaceutical (tablet excipient, bulk laxative)
*Substitute for gum tragacanth
Gum karaya

Gellan gum as gelling agent

Gellan gums are gelling polymers. It has only relatively recently been introduced as a gelling agent. Gellation requires divalent cations in the media and in general gellan gums provide a more transparent matrix.

Gellan gum first received approval for food use in Japan in 1988. It is a microbial polysaccharide derived from the organism Pseudomonas elodea, is a linear polymer with a tetrasaccharide repeat unit consisting of glucose, glucuronic acid, glucose and rhamnose.

It is now approved for food, nonfood, cosmetic and pharmaceutical use in the USA, Canada, Australia and many other countries in Latin America South America, Asia and the European Union.

Gellan gum is used commercially in a wide range of food applications:
*Water based gels
*Fabricated foods
*Bakery applications
*Pie fillings and puddings
*Dairy foods
*Beverages
*Confections
*Fruit applications

Gellan gums can be used in milk based products and it is possible to hydrate gellan gum directly in milk by heating to above 75 °C.

In dairy products at acid pH (such as yogurt, sour cream, or direct acidified milk gels) it is necessary to include another hydrocolloids (such as CMC or guar gum) to act as a protective colloid and prevent precipitation of the milk protein.

In pharmaceuticals application, gellan gum has been used as a novel drug-delivery vehicle, in film formation for transdermal for drug delivery and as a component in controlled –released system.
Gellan gum as gelling agent

Tragacanth as food additive

Tragacanth is a dried exudation obtained from stems and branches of the shrub Astragalus gummifier. Tragacanth gets its name from the Greek words ‘tragos’ and ‘akantha’ – provably because the dried plant sap is curved or twisted.

The exudate is allowed to dry on the shrub before collection and is produced in two forms – ribbons and flakes. After collection, the gum is graded and milled to a powder. Tragacanth is used in food as emulsifier, preservative and thickener.

Tragacanth is permitted generally in foodstuffs except those where additives are not permitted.

It is used in baked goods, citrus beverages, condiments, fats, fruit filings, gravies, meat products, oils, relishes, salad dressing, milk powder stabilizers, cheese and sauces.

Tragacanth is a complex branched of polysaccharide consisting of two main fractions. The major fraction is not soluble but swells in water to form a gel.

The second fraction is water soluble and tragacanth contains small amount of protein which may be involved in its emulsifying properties.
Tragacanth as food additive