The feasibility of extracting lignans from flaxseed meal using pressurized low polarity water (PLPW) in a fixed bed extraction cell was evaluated. Optimization experiments were performed using surface response methodology for flow rate, bed depth and solvent to solid ratio (S/S). Maximum yield of lignan was obtained at flow rate of 0.6-2 mL/min, bed depth to internal diameter ratio (L/ID) of 20-25, and S/S ratio of 77-150 mL/g. The effect of flow rate and the mass transfer mechanisms governing the extraction of lignans from flaxseed meal was also evaluated. A diffusion model and a two site kinetic model were used to describe the extraction of lignans from flaxseed meal by PLPW. The two models gave similar quality of data fits. The diffusion model yielded diffusivities ranging from 2 x 10(-13) to 9 x 10(-13) m(2) s(-1) for extraction of lignans at 180 degrees C, pH 9 and a 1:1.5 meal to co-packing material ratio. (c) 2008 Elsevier Ltd. All rights reserved.