Studies on the steady shear flow behavior and functional properties of Lepidium perfoliatum seed gum

Flow properties of Lepidium perfoliatum gum, extracted from Qodume shahri seeds, as influences of concentrations (0.5%, 1%, 1.5% and 2%), temperatures (5, 25, 45, and 65 °C), salts and pHs were investigated. Among the selected models, power law model well described the rheological behavior of the L. perfoliatum seed mucilage solutions with high determination coefficients, R² and low root mean square error (RMSE). Non-Newtonian shear thinning behavior was observed at all temperatures and concentrations. While increase in temperature decreased the viscosity and increased the flow behavior indices, adverse effect was obtained by increasing the concentration. The temperature effect was more pronounced at 0.5% L. perfoliatum seed gum concentration and indicated the higher activation energy (E_a: 31614.56 J/mol). The viscosity was dependent on type of salt addition, and decreased with salt concentration. This behavior was more evident when using divalent salt. A marked dependence of viscosity on pH was also observed, as pH increased from acidic to alkaline conditions, the viscosity increased until pH of 9 and afterward decreased. The hydrocolloid showed good water absorption capacity (WAC) and imparted relatively high stability to foam and oil-in-water emulsion. However, the gum solubility was low at all temperatures studied (30, 60 and 90 °C).