1. Radiation treatment caused exponential reduction in the hardness of raw carrot at the doses from 0.19 to 3.06Mrad. Regardless of blanching treatment after irradiation, irradiated raw carrotat low doses (0.21 and 0.43Mrad) showed faster dehydration while at higher doses (0.86 and 1.17 Mrad) slower dehydration than non-irradiated carrot. The water absorption of dried carrot was accelerated by irradiation of raw material with increased dose level.
2. The changes of swelling velocity were determined using an apparatus for the measurement of the total volume decrease by rehydration of dried carrot in the water under reduced pressure at 35°C. The decrease in the total volume and weight of absorbed water may indicate that a more greater combination or chemical reaction between water molecules and the micelles takes place in the irradiated dried carrot than in the non-irradiated one. These reactions would cause remarkable decrease of total volume with only a slight acceleration of the swelling of the carrot due to absorbed water.
3. In both raw and dried carrot, the radiation treatment caused the decrease of total pectic substances and protopectin and the slight increase of the pectate and the pectin with the increased dose level.
4. No significant differences in flavor and taste after rehydration were detected in irradiated carrot and at the doses of 0.25 and 1.0 Mrad required only two-thirds and a half of cooking time, respectively, of that necessary for non-irradiated carrot.