Determination of Drying Pattern of Radish Slabs under Different Drying Methods Using Imaging Process = Determination of Drying Pattern of Radish Slabs under Different Drying Methods Using Imaging Process

다국어 초록 (Multilingual Abstract)

Drying kinetics and pattern in the thin layer of radish slabs were determined in this study. Drying was performed in lab-scale combination dryer. Combination dryer has consisted of hot air temperature and velocity controller and microwave power supply that preset microwave power level could be manually controlled range from 0 to 1000 W. The applied hot air temperature and velocity was 5 m/s and 50 and 70 °C, respectively, and preset microwave power levels were 50 W. Radish slabs, approximately 40×40 mm in area and 5 mm in thickness, was used for the experiment. Drying kinetics of radish slabs under hot air drying, microwave drying, and microwave - hot air combination drying were compared and the drying pattern such as moisture evaporation pattern on radish slabs subjected to different drying methods was visualized with the application of hyperspectral image processing. As a result, an opposite drying pattern was obtained at hot-air drying and microwave drying. The dried samples by hot air had a higher moisture content at the center than the edge. In contrast, dried samples by microwave had a higher moisture content was observed in edge side. Hence, the combination of opposite drying pattern led to the results that a relatively uniform drying pattern of radish slabs during the drying process. In particular, drying uniformity was improved when simultaneous hot air temperature at 70 °C and microwave drying. The results showed that drying uniformity of radish slabs could be improved by combined hot air and microwave drying method, with the advantages of shortening drying time.