The effect of postharvest long-term storage and pre-treatments on the mass transfer rates during osmotic dehydration of carrots was investigated. Four blanching times were used and the carrots were sampled during 12 weeks of storage. Cell vitality was measured by isothermal calorimetry on cores taken from blanched slices. During the storage period, effective diffusion coefficients for water and sucrose transport were determined in the non-blanched and blanched carrot parenchyma. For every time point during long-term storage, the effective diffusion coefficients increased with an increase in blanching time which caused the death of cells in the tissue. This increase showed to be dependent on the storage time of the carrots. It was inferred that structural changes in the cell wall of the carrot parenchyma during storage substantially decreases the effect of blanching on the effective diffusion coefficients. (c) 2006 Elsevier Ltd. All rights reserved.