Effects of freezing and thawing on the physical and electrical properties of dehydrated radish

Abstract

This study was carried out to determine the optimum conditions for dehydrofreezing radish and the suitable thawing method for dehydrofrozen radish. Changes in the physical properties of radish during dehydrofreezing, thawing, and re-hydration were observed and the effects of these processes on the physical properties were evaluated. Consequently, for the dehydration process, vacuum drying under low temperature (20°C) was selected to avoid deterioration. For the freezing process, the time required to pass the zone of maximum ice crystal formation for dehydrating by the brine freezing method was shortened 70-90% compared to the normal freezing method. The amount of drip loss after thawing was the least in the sample dehydrated by brine freezing followed by thawing at 0°C. Electrical properties, which were obtained by measuring the impedance after each process, were used as an index to evaluate product freshness.