DIFFUSION IN HEATED POTATO TISSUES

Data to optimize nutrient retention during processing of potatoes were obtained by measuring loss of solutes (glucose, fructose, citric acid , potassium, calcium and magnesium) by diffusion into blanch water. Ap parent diffusivities were calculated based on Fickian diffusion. Magne sium and calcium did not follow the Fickian approach with the same acc uracy as the others. A hindrance factor (K), the ratio of apparent dif fusivity in potato to a published value was used. The hindrance factor was calculated at reference temperature 25-degrees-C to separate preh eating effects from the direct effect of temperature on diffusion coef ficients. A mathematical model for K(T,t) was fitted to experimental d ata for each solute. All solutes showed a sharp decrease of hindrance factor in the region 50-60-degrees-C. These models showed, however, th at heating of potato affected diffusivities of the solutes to differen t degrees. Ions had a limit solution retention in the tissue higher th an glucose, fructose or citric acid.