Guar gum (E412) is used as a thickener in
sauces, salad dressings, as a stabiliser in ice cream that
prevents ice
crystals from forming, and as a fat substitute that adds the "mouth
feel" of fat.
In pastry fillings, it prevents "weeping" (syneresis)
of the water
in the filling, keeping the pastry crust crisp.
It has a very high viscosity (thickness) even when very little is used.
When mixed with xanthan gum or locust bean gum, the viscosity is more than when
either one is used alone, so less of each can be used.
APPLICATION
FUNCTION
Soups, sauces and marinades
Viscosity control.
Pastry fillings
Viscosity and syneresis control.
Ice Cream
Ice crystal and Viscosity control. Fat mimetic.
Chemistry
Guar gum (E412) is a polysaccharide (a long chain made of
sugars) composed of galactose and mannose.
Guar gum comes from the endosperm of the seed of the legume Cyamopsis tetragonolobus,
which is an annual plant grown in arid regions of India.
Properties
Guar gum is an economical thickener and stabiliser. It hydrates fairly rapidly
in cold water to give highly viscous, pseudoplastic solutions of generally greater
low-shear viscosity when compared with other hydrocolloids and much greater than
that of locust bean gum. High concentrations (~ 1%) are very thixotropic but
lower concentrations (~ 0.3%) are far less so.
Guar gum is more soluble than locust bean gum. Unlike locust bean gum, it does
not form gels but does show good stability to freeze-thaw cycles. Guar gum shows
high low-shear
viscosity but is strongly shear-thinning. Being non-ionic, it is not affected
by ionic concentration or pH but will degrade at pH extremes at temperature (e.g.
pH 3 at 50°C). It shows viscosity synergy with xanthan gum. With casein,
it becomes slightly thixotropic forming a biphasic system containing casein micelles.
When guar gum is dissolved in hot or cold water, it takes around 4 hours to reach
maximum viscosity.
It is not advisable to use more than 0.4% w/w Guar gum in a formulation as it
can give a “mealy” taste to the finished product.