Variations in Temperature and Relative Humidity of Rough Rice in the Polypropylene Bulk Bag during Waiting Time for Drying
2010
Lee, C.K., National Institute of Crop Science, RDA, Suwon, Republic of Korea | Yun, J.T., Rural Development Administration, Suwon, Republic of Korea | Song, J., Rural Development Administration, Suwon, Republic of Korea | Jeong, E.G., Rural Development Administration, Suwon, Republic of Korea | Lee, Y.Y., National Institute of Crop Science, RDA, Suwon, Republic of Korea | Kim, W.H., National Institute of Crop Science, RDA, Suwon, Republic of Korea
The uses of the polypropylene bulk bags having the loading capacities more than 500 kg are increasing in Korea recently as a storage container for rough rice. This study was performed to obtain the basic information on the changes of temperature and relative humidity in the bulk-bag-stored high moisture rough rice during waiting for drying. At the moisture content more than 22% on wet weight basis of paddy, the bulk-bag inside temperature rose up to more than 40℃ and then slid down during storage. For example, in case of Hwaseongbyeo, 26.5% moisture content of rough rice (MCRR) harvested at 46 days after heading (DAH) showed 54.5℃ of peak temperature at 66.8 hours after bulk-bag loading, 22.5% MCRR harvested at 52 DAH exhibited 42.0℃ at 81.1 hours, and 19.7% MCRR harvested at 55 DAH displayed 38.9℃ at 119.0 hours. There were a good linear relationship between peak temperatures of bulk-bag inside and moisture contents of paddy (r²=0.89 in 2005, and 0.87 in 2006), while the slope and intercept of the linear regression equation was affected by the environmental conditions such as ambient temperatures and microbial flora. The peak temperatures increased with the rate of about 2.74-3.33℃ per every 1% increase of moisture content at higher moisture contents of paddy than 19%. The relative humidity varied depending on bulk-bag inside temperature and rough rice moisture content, and showed the range of 94.2% to 99.9% in the central point of the bulk-bag. The results suggested that a rapid drying treatment as soon as possible was needed to produce a good quality of rice when the paddy of high moisture more than 22% on wet basis was harvested in a bulk-bag especially at high ambient temperature.
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