Theological studies on plum gum dispersions: I general flow characteristics

ABSTRACT

The rheology of plum gum dispersion was studied utilizing the reoviscometer. The rheogram of 5% w/w gum dispersion is indicative of a pseudoplastic system, which becomes clearly plastic upon increasing gum concentration. It was also evident that sum dispersions exhibit thixotropic behavior. At relatively low concentrations [0.25-2% w/w], it was not possible to establish the actual flow pattern. Therefore, the characterization was based on measurements of relative viscosities. Various factors which influence the relative viscosity of gum dispersion, as gum concentration, preservatives type, hydrogen ion concentration and effect of heat were studied in the light of the factor of time. The relative viscosity of 2% w/w gum dispersion was reduced by about 90% by increasing the temperature from 25C to 100C. On aging, the dispersions lost part of their viscosities. Phenylmercuric nitrate was found to be the best among the other preservatives tested. Plum dispersions appeared to be most stable at pH 6 and lowering in the relative viscosities was noticed on aging