To develop a new cooking method for rapid rehydration of dried radish (strips of dried radish), several conditions for rehydration including a step of ultrasono-irradiation were studied. The conditions for the best rehydration were determined at 5,25 and 40°C and the effects of ultrasonication on physical properties and palatability of the cooked radish were investigated. The results were as follows:
(1) The amount of water absorbed into dried radish increased as the rehydration time goes up. The irradiated radish showed further improved swelling in shorter time and their tissues were softened faster than those in the control without irradiation.
(2) When rehydration was conducted under the suitable conditions at the water temperature of 25°C, no difference was observed between the subjects irradiated for 15 min and those soaked for 30 min without irradiation, with regard to in the contents of moisture, total sugar, free sugar, crude protein, free amino acids and ashes, and the remaining proportions of mineral components in both subjects were 81% for Ca,70% for iron and 69% or more for Mg.
(3) For texture characteristics, ultrasono-irradiated radish after cooking exhibited large rupture strain and chewiness than the control without irradiation. In addition, the permeability of seasonings was a little higher in ultrasono-irradiated radish and also the odor specific to the dried radish was somewhat decreased, resulting in superior taste evaluation.