Extraction, Characterization and Rheological Behavior of Tamarind Gum Under High Salinity

Abstract

The objective of this work was to obtain tamarind gum from Tamarindus indica L. seeds, which are waste from the food industry. Tamarind gum was extracted by two methods and the highest yield achieved was 32.6% w/w, containing 69.25% w/w of organic matter, which was composed mostly of the nonionic polysaccharide xyloglucan. The greatest molar mass of the tamarind gum was Mw = 7.16 x 105 g mol-1 with polydispersity index (PI) of 1.7. Evaluation of the rheological behavior of tamarind gum samples were carried out in two brines (total dissolved solids values of 29,711 mg L-1 and 68,317 mg L-1, containing divalent ions) that simulated petroleum reservoir salinity levels, with different temperatures (25, 60 and 80 °C). The rheological curves indicated high salt resistance of the gum samples. Under a shear rate of 7.3 s-1 the highest viscosity values found were approximately 86, 41 and 50 cP with a concentration of 5,000 ppm and temperatures of 25, 60 and 80 ºC, respectively.