Rheological properties of mucilage extracted from Alyssum homolocarpum seed as a new source of thickening agent

The rheological properties of Alyssum homolocarpum seed mucilage as influences of gum concentrations (1.5%, 2%, 2.5%, 3%, 3.5% and 4%) and temperatures (5, 25, 45, and 65 °C) were investigated. Effects of pH (3–9), salts concentrations (CaCl2 and MgCl2 from 0 to 0.049 M; NaCl and KCl from 0 to 0.17 M) and sucrose concentration (0% to 40%) were also evaluated at 3% weight/weight (w/w) of A. homolocarpum seed gum. The power law model well described the rheological behavior of the A. homolocarpum seed mucilage solutions with high determination coefficients, R2. The gum exhibited non-Newtonian, pseudoplastic behavior at all temperatures and concentrations. An increase in concentration, decreased the flow behavior indices, n, and increased the consistency coefficients; k. Increasing temperature decreased the viscosity and pseudoplasticity. The temperature effect was described using Arrhenius equation and as the activation energy (Ea) decreased the gum concentration increased. The apparent viscosity varied according to variation in pH, the highest viscosity was obtained at pH of 9 and the lowest at pH of 3, nevertheless there were no significant difference between pH ranging from five to nine. The apparent viscosity decreased with addition of Na+, K+, Ca2+ (<0.01 M) and Mg2+ (<0.039 M), whereas it increased with the addition of Ca2+ and Mg2+ at concentration higher than 0.01 M and 0.039 M, respectively. An increase in concentration was accompanied with an increase in pseudoplasticity (increase in k and decrease in n).