Preliminary Evaluation of a Process for Producing Refined Guar Splits for a Target Guar Solution Viscosity

Abstract.

The objective of this study was to conduct a preliminary assessment of a method to produce refined guar splits that will have a white color and reach a viscosity of 6,500 centipoise at a 0.92% solids concentration. Processing steps analyzed included drying, milling, sieving, and polishing. Mathematical relationships were established to determine the effect of process parameters on product color and viscosity. The target viscosity was not reached during initial tests after original processing and an additional separation step was added to further remove hulls and dust. An increase in viscosity was recorded for all samples, and the target viscosity was only reached by some of the samples. A maximum viscosity of 6,510 centipoise was reached at 121°C, 20 min of roasting time, and 30% mass loss. Color and viscosity of the guar gum-water mixture were affected by the polishing time and heating temperature. Increasing polishing time increased viscosity but reduced yield. Increasing heating temperature had some desirable effects on viscosity and color, but extra costs will be associated with higher energy demands. Raw bean color affects the color of the refined splits and more uniform raw material is recommended.