88E-12 |
Blanching and drying conditions of Korean traditional vegetables |
J. B. EUN, B. R. Yoo, and K. Kim. Department of Food Science and Technology, Chonnam National University, 300 Yongbong-dong Buk-gu, Kwangju, 500-757, South Korea Drying vegetables which can be preserved for long period is also popular as good source for dietary fibers. However, only few studies on the drying methods of Korean traditional vegetables for the mass production have been reported. In this study, blanching and drying conditions of three Korean traditional vegetables were investigated to use as dried vegetables. Peroxidase activity was used to determine optimum blanching time and method. A Hunter colorimeter was used to determine color of fresh and rehydrated dried-vegetables. Variation of moisture contents in the vegetables were monitored during drying process by AOAC method. The moisture contents were 87% in Ligularia fiscberi and Playcodon grandiflorum, and 89% in Pteridium aquilinum. When boiled in water, peroxidase activity in Playcodon grandiflorum was inactivated after 10 sec blanching and after 20 sec in Pteridium aquilinum and Ligularia fiscberi. When steamed, the enzyme activity in Playcodon grandiflorum was inactivated after blanching for 20 sec and after 60 sec in Pteridium aquilinum and after 300 sec in Ligularia fiscberi. L values increased in dried and rehydarated dried-Ligularia fiscberi branched with boiling water and decreased when they are not blanched previously. However, L values decreased in Pteridium aquilinum and Playcodon grandiflorum regardless of blanching. Drying time to reduce moisture to 10% was 8 hrs for Pteridium aquilinum, and 10 hrs for Ligularia fiscberi and Playcodon grandiflorum at 50 oC. Rehydration rate of dried vegetables was 250% for Pteridium aquilinum, 260% for Ligularia fiscberi and 220% for Playcodon grandiflorum. In conclusion, for Pteridium aquilinum, optimum blanching time with boiling water was 5 min and drying time was 8 hrs at 50oC to result in removal of ptaquiloside, a toxic substance. For Ligularia fiscberi and Playcodon grandiflorum, optimum steam blaching times were 3 min and 30 sec and drying time was 10 hrs at 50oC.
Session 88E, Fruit & Vegetable Products: Processing
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