稻穀乾燥均化時間對乾燥速率與品質之影響

The Effect of Tempering Period on Drying Rate and Quality of Rice

盛中德(Chung-Teh Sheng) ； 湯雁翔(Yen-Hsiang Tang) ； 郭鳳瑞(Fong-Ruey Guo) ； 黃明仕(Mins-Shi Huang)

《農業機械學刊》 6卷2期 (1997/06) Pp. 69-79

https://doi.org/10.30062/JAM.199706.0007

摘要

國內常用之循環式乾燥機，其乾燥方式爲間歇乾燥，而間歇乾燥包括乾燥時間與均化時間，在乾燥時乾燥時間常爲固定，均化時間的長短對稻穀乾燥速率與品質有相當重要的影響。本研究乃針對在間歇乾燥作業，進行均化時間對稻穀乾燥速率與品質影響之研究。
乾燥試驗結果，就不包含均化時間而言，當固定熱風乾燥時間，增加每循環乾燥期間之均化時間，可以提高實際的平均乾燥速率；就包含均化時間而言，乾燥速率隨著均化時間的增長而降低。在本試驗條件範圍內，當乾燥溫度超過50℃時，白米率有明顯隨溫度下降的趨勢，間歇式乾燥之白米大於連續式乾燥，故均化作用有助於白米率的提升。乾燥溫度對完整米率的影響較乾燥／均化時間爲大；當乾燥溫度超過50℃以上，無論間歇式乾燥或連續式乾燥，完整米率皆有明顯的下降。間歇式乾燥之完整米率大於連續式乾燥，並且隨著均化時間的減少而降低，當乾燥／均化時間小於10/70時，完整米率有明顯的下降。爲避免完整米率的下降，每循環乾燥期間乾燥時間與均化時間的比應大於1：7。乾燥溫度對發芽率的影響較乾燥／均化時間爲大，當乾燥溫度大於60℃時，發芽率明顯地下降，間歇式乾燥之發芽率較連續式乾燥爲高。

關鍵字

稻穀干燥 ； 均化時間 ； 乾燥速率

並列摘要

The manner of recirculating rice dryers which is extensively used in Taiwan is intermittent drying. Intermittent drying is composed of heating and tempering. A drying cycle includes heating time and tempering time. In a drying cycle, the drying time is used to be fixed and the tempering time changes and significantly affects the drying rate and milling quality of rice. This study focuses on the effect of tempering time on drying rate and milling quality of rice for recirculating drying.
According to the experimental results, If the tempering time is not included, the heating time is fixed an the tempering time in a drying cycle increases. It points out extending the tempering time for a drying cycle can increase the average drying rate. for onlythe heating period. On the contrary, if the tempering time is counted, the drying rate will decrease withthe increase of the tempering time. When the drying air temperature is above 50℃, the percentage of polished rice drops obviously. The percentage of olished rice for intermittent dryingis higher than continuous drying. Tempering process enefits the production of polished rice. The drying air temperature influences more on the head yield than the time ratio of heating and tempering. When the drying air temperature is over 50℃, head yield drops obviously for both intermittent drying and continuous rying. The percentage of head yield of intermittent drying is always higher than continuous drying. The percentage of head yield decreases with the decrease of tempering time. When tempering time is less than 760 minites, the percentage of head yield declines significantly. Therefore, in order to prevent the loss of the percentage of head yield, the tempering time in a drying cycle should not be less than 1/7. Drying air temperature influences the percentage of germination more than tempering. When the drying air temperature is above 60℃, the percentage of germination drops apparently. The percentage of germination for intermittent drying is higher than continuous drying.

並列關鍵字

Rice drying ； Tempering period ； Drying rate