Tamarind Gum

Tamarind Gum

 

Tamarind gum, also called tamarind seed polysaccharide (TSP for short) is a kind of neutral polysaccharide substance extracted and separated from endosperm of legume tamarind plant seeds. It is easy to disperse in cold water and then with heat, it will form viscous liquid. Tamarind gum has favorable resistance to heat, acids, salts, freezing and thawing, as well as stabilizing, emulsifying, thickening, coagulating, water retention and film forming functions. Besides, its aqueous solution has strong viscosity and the viscosity won’t be affected by acids and salts, so it is a food additive with wide use.

 

Molecular Structure of Tamarind Gumtamarind-gum-powder

 

Tamarind gum is mainly made up of the neutral polysaccharide consisting of D-galactose, D-xylose and D-glucose (1:3:4) and a little free L- arabinose.

 

Tamarind gum is free flowing, odorless, tasteless and milk white or light beige powder. With the reduction of gum purity, the color of products will gradually deepen. It has a grease smell and is also apt to caking. Besides, it is insoluble but can disperse in cold water, and it can dissolve in hot water but is insoluble in most organic solvents. Tamarind gum itself uncharged and belong to neutral plant colloids.

 

Properties and Functions of Tamarind Gum

 

The aqueous solution of tamarind gum is slightly sticky without threading and its viscosity is very similar to that of starch. In addition, ageing phenomenon will appear in the starch solution during storage and its resistance to acids, bases, salts and heat becomes poor while tamarind gum shows good properties in these aspects.

 

In the food industry, tamarind gum can partly or wholly replace starch. For example, for some kinds of sauces in Western-style food, the addition of vinegar will lower the pH value and these sauces also require relatively high viscosity. Consequently, if the starch alone is used to increase viscosity, then plenty of starch is needed to reach the required viscosity. Furthermore, the starch will generate aging phenomenon during the storage of sauces, leading to the increase of viscosity or even the formation of gel, the decrease of liquidity, or the significant decrease of viscosity resulting from acid decomposition and the appearance of layering. However, a small amount of tamarind gum can replace part of starch to improve the taste and stability of sauces.

 

Tamarind gum is a kind of vegetable gelatin with relatively strong hydrophilicity. It will dissolve and form uniform colloidal solution when heated up to 85℃ after dispersing in cold water. The viscosity of colloidal solution is related to mass concentration. When the mass concentration of tamarind gum solution is lower than 158 g/L, the solution will show Newtonian fluid properties. However, when it is more than 158 g/L, the solution will show rheological properties of non-Newtonian fluid, that is, the solution has the thixotropy and pseudoplastic properties of shear thinning.

Heating and boiling have a great effect on the viscosity of tamarind gum solution. When the solution is boiled for about 20-30 minutes, the viscosity will first reaches the maximum and then decrease but thermal stability is relatively high. After boiling for 5 hours, the viscosity will only decrease to half of the maximum.

 

When the pH value is 7.0-7.5, tamarind gum is relatively stable but beyond this range, its viscosity will then decrease. In the inorganic acid medium, the viscosity strikingly decreases. However, with the use of organic acids, the solution viscosity is slightly affected by the pH value when the pH value is 2-7, and the reason for the viscosity decrease is caused by depolymerization of high polymers. While the pH value is 7.0-7.5, the viscosity will reach the maximum and it is caused by extension of molecules.

 

Tamarind gum solution has strong consistence and is usually insoluble in such organic solvents as alcohol, aldehyde and acids but mutually soluble with glycerin, sucrose, sorbitol and other hydrophilic colloids. Furthermore, it will form gel when meeting alcohol and the mixing with sodium tetraborate form semi-solid state but will become liquid gelatin with heat.

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On July 25th, 2013, posted in: Products and Techniques, thickeners by Tags: ,

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