Physicochemical aspects of hydrocolloid extract from the seeds of Lepidium sativum

Summary Acid equivalent weight, intrinsic viscosity and FT‐IR measurements have demonstrated a polyelectrolyte nature to Lepidium sativum seed extract. The polyelectrolyte nature relates to the carboxyl groups carried by galacturonic acid and glucuronic acid unit. The seed extract exhibited pronounced shear thinning in steady shear rheology and a weak gel type behaviour in dynamic rheology when the concentration is high i.e. > 1%. Such behaviour suggests the ability of L. sativum seed extract to structure a liquid, thus showing the possibility of applying it as a novel thickener and stabiliser in aqueous systems. The characteristic could be due to a strong tendency of molecular association of L. sativum seed extract as found for high M/G ratio galactomannans, and possibly also the enhanced macromolecular entanglement due to relatively rigid chain conformation. Temperature dependence study showed that the rheological properties of L. sativum structured solution is stable against temperature variation.