Effective diffusivity of total solids and pectic substances from apple tissue

The effective diffusivities of total solids and pectic substances from apple tissue were determined at 40 and 60 degrees C in water and buffer; the addition of pectolytic enzyme in buffer at 40 degrees C was also investigated. The Fickian model for unsteady-state diffusion was applicable in all cases. Effective diffusivity values both for total solids and soluble pectic substances in deionized water were temperature dependent. The effective diffusivity values for total solids loss were reduced by the presence of buffer at 40 degrees C but not at 60 degrees C. The effective diffusivity values for soluble pectic substances were not affected by buffer at 40 degrees C but were noticeably lower at 60 degrees C compared to deionized water at the same temperature. The addition of a pectolytic enzyme preparation did not improve the mass transfer of either total solids or soluble pectic substances.