Chemistry Reference
In-Depth Information
5.4
FOOD INGREDIENTS AND THEIR EFFECTS
ON XANTHAN GUM FUNCTIONALITY
Xanthan gum is an anionic polysaccharide. Food components such as
salts and acids will influence the ionic strength of the environment,
which will, in turn, influence the functionality of the xanthan gum
through changes in the balance of the charges. Other charged molecules
such as proteins also have the potential to influence the functionality of
the xanthan gum.
5.4.1
Salts
The hydration rate of xanthan is decreased in the presence of salts.
Fig. 5.7 shows that after 30 minutes of mixing at 650 rpm with a
propeller-type mixer, full viscosity is not developed above approxi-
mately 2% NaCl. It is recommended that, when possible, xanthan is
hydrated in the water before the addition of salt. However, continued
mixing will eventually lead to full development of the viscosity at higher
salt levels. Once hydrated, xanthan has very good salt tolerance and up
to 20-30% salt can be added without adversely affecting the viscosity.
The effect of salts on the viscosity is dependent upon the concen-
tration of the xanthan gum. At low concentrations of xanthan, below
approximately 0.3%, addition of salts results in a slight decrease in the
viscosity. At concentrations above 0.3%, addition of salts results in an
increase in viscosity (see Table 5.1). The viscosity of the xanthan gum
solution is equivalent in deionised water and 1% KCl at 0.3% gum.
100
10
1
0.1
1
10
NaCl (%)
Fig. 5.7
Viscosity of 0.3% xanthan gum after 30 minutes mixing at medium shear
(650 rpm propeller mixer).
