Resumen:
Tamarind seed mucilage (TSM) was extracted and obtained by spray drying. The power law model well described the rheological behavior of the TSM dispersions with determination coefficients R2 higher than 0.99. According to power law model, non-Newtonian shear thinning behavior was observed at all concentrations (0.5%, 1%, 1.5% and 2%) and temperatures (25, 30, 40, and 60 °C) studied. Increasing temperature decreased the viscosity and increased the flow behavior index, opposite effect was observed when increasing the concentration. The temperature effect was more pronounced at 2.0% TSM concentration with an activation energy of 20.25 kJ/mol. A clear dependence of viscosity on pH was observed, as pH increased from acidic to alkaline conditions, the viscosity increased. It was found that the rheological properties of TSM were affected by the sucrose and salts and their concentrations as well due to the addition of ions (or sucrose) decreases repulsion and allows molecule expansion promoting a significant reduction in viscosity. These results suggest that TMS could be applied in the production of foods that require additives with thickening capacity
Descripción:
The analyzed Tamarind seed mucilage dispersions presented a Non-Newtonian shear thinning behavior (n < 1). The power law model well described the flow properties of the dispersions. Increasing the solution concentrations increased the viscosity and pseudoplasticity while increasing temperature resulted in a decrease in viscosity and pseudoplasticity. In addition, temperature dependency of the consistency index for the gum solutions was well described by the Arrhenius model. The influence of pH was the variable with the most significant effect on the flow behavior and rheological properties of TSM, when pH increases, apparent viscosity increased, this may be associated with an increase in charge density promoting a contraction of the TSM molecules. Addition of salts to TSM dispersions resulted in a diminution of k and an increment of n, promoting a decrease on apparent viscosity, suggesting that the molecular structure of the TSM is negatively charged, behaving like a polyelectrolyte. Addition of sucrose did not influence significantly apparent viscosity. According to the results of this study, it can be concluded that TSM could be potentially applied as hydrocolloid in order to achieve a superior quality for new and existing hydrocolloid added products.