DIFFUSIVITY DATA OF AN ARTIFICIAL FOOD SYSTEM

A diaphragm cell was used to determine diffusivity properties of an ag arose gel. The apparent diffusivities of thiamine and glucose were mea sured using a steady-state method. The effects of temperature (20-80-d egrees-C), pH (4 and 7), and weight fraction of agarose (2-6%) on appa rent diffusivities were investigated Values of D(app) were found to be in the range 4.29 x 10(-10)-16.72 x 10(-10) M2/s, and could be relate d to temperature by an Arrhenius-type equation, with activation energi es in the range 17.1-19.1 kJ/mol. The apparent diffusivities of thiami ne were higher in a citrate/hydrochloric acid buffer (pH 4) than in a phosphate buffer (pH 7), while the diffusivities of glucose were not a ffected by the type of buffer. The apparent diffusivity of glucose at 25-degrees-C could be related to the weight fraction of agarose by a m odified version of the Mackie-Meares equation.