Leaching losses of potassium during soaking in hot water and application of microwave for blanching potatoes

Abstract

The leaching losses of potassium from potatoes during soaking in hot water were measured at four temperatures ranging from 70°C to 100°C. The infinite cylinder diffusion model was used to describe the leaching losses, and the measured data were fitted to a model using a non-linear least squares method. The measured results agreed well with the calculated results. The values determined for the diffusion coefficients were 1.05×10 -6 to 2.05 × 10 -6 (m 2-s -1), and the apparent activation energy determined from an Arrhenius-type equation was 24.4 (kJ-mol -1). The applicability of using microwave for blanching potatoes was also examined. Changes in enzyme (peroxidase) activity, texture and potassium content were measured and compared between blanching by boiling water, microwaves or a combination of microwaves and boiling water. The combination of microwave and boiling water required the least amount of time for inactivation of the enzyme. Blanching using microwave tended to damage samples. Moreover, blanching using microwaves caused significant softening while the combination of microwave and boiling water caused less change in shape and texture. The residual ratio of potassium in the sample blanched using a combination of microwave and boiling was approximately 80% ; similar to that of potatoes blanched using boiling water. These results suggest that the combination of microwave and boiling water can be used for blanching potatoes.