The Effect of tempering period on drying rate and quality of rice

• Main Authors: Tang, Yen-Teh Sheng, 湯雁翔
• Other Authors: Chung-Teh sheng
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/80788352276958334215

碩士 === 國立中興大學 === 農業機械工程學系 === 84 === The manner of recirculating rice dryers which is extensively used in Taiwanis intermittent drying. Intermittent drying is composed of heating and tampering. 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 signifcantly affects the drying rate and milling quality of rice.this study focus on the effectof tempering time on drying rate and milling quality of rice for recirculating drying. the testing items of quality includethe percentage of brown rice, polished rice, head yield and germination rate. According to the experimental results, the following conclusions are drawnas below:<1> If the tempering time is not included, the heating time is fixed and the tempering time in a cycle increase, the total heating time become longer. It points out extending the tempering time for drying cycle can increase the average drying rate for only the heating period. On the contrary, if the tempering time is counted, the drying rate will decrease with the increase of the tempering time.<2> When the drying air temperature is above 50℃,the percentage of polished rice for intermittent drying is higher than continuous drying. Tempering process benefits the production of polish rice.<3> The drying air temperture 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 drying.<4> The percentage of head yield of intermittent drying is always higher than continuous drying. the percentage of head yield decrease with the decrease of the tempering time. When tempering time is less then 70 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 then 1/7.<5> Drying air temperature influence the percentage of germination more then 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.