Influencing Factors of the Viscosity of Xanthan Gum Solution
The factors that affect the viscosity of xanthan gum solution include solute concentration, temperature (both the dissolving temperature and the measured solution temperature), salinity and PH value.
1. Effects of Temperature
The viscosity of xanthan gum solution is affected by both the dissolving temperature and the measured solution temperature. Like most kinds of solutions, it decreases as the solution temperature rises and the change process is completely reversible in temperature 10°～80°.
2. Effects of Salinity
Salinity certainly plays a part in the viscosity of xanthan gum solution. In lower concentration conditions, the viscosity may slightly decrease by adding a small amount of salt. This is mainly caused by the decrease of intermolecular charge force. In higher concentration circumstances, otherwise, the viscosity will increase by adding a large amount of salt. When the salinity is over 0．1％ (W／V), however, viscosity won’t be affected by salinity. In a range of PH value, polyvalent metal salt can form gels with xanthan gum. For example, calcium salt and magnesium salt can form gels in PH value 11～13 while the trivalent metal salt can form gels in lower PH value.
3. Effects of PH Value
Compared with other factors, the PH value has a little effect on the viscosity of xanthan gum solution. When the PH value is below 3, pyruvic acid and acetyl will begin to strip. While it is over 9, the acetyl on the side chain will be stripped. As the researchers have pointed out, the deacetylated xanthan gum which also stripped pyruvic acid has the same effect on the solution viscosity as the wild type of xanthan gum.