Differences in breaking behavior of rice leaves under microwave and naturally drying processes

In order to fight for good farming time or harvest in bad weather,combine harvester will produce more broken leaves when threshing high moisture content rice,which will seriously hinder the grain cleaning effect.In this study,the breaking behavior of rice leaves under different microwave drying time and drying power was studied.Firstly,based on the appearance of freshly rice leaves undergoing microwave drying,the changing property of moisture content,weightlessness rate and temperature rise of rice leaves were tested and analyzed.Secondly,the tensile breaking force of freshly rice leaves under different microwave drying time and drying power was tested and compared with the tensile breaking force of naturally dried rice.Finally,the optimal microwaves parameters of rice leaves after drying which could result in greater breaking force than the natural drying state were obtained.The result showed that microwave drying method will reduce the moisture content of rice leaves and change the microstructure,which would affect the tensile-breaking property of rice leaves.The maximum tensile breaking force of rice leaves appeared at microwave dried power 70 W for 5-8 min and at microwave dried power 210 W for 3-4 min.The tensile breaking property of rice leaves at microwave dried power 350 W for 6-8 min were the weakest,which was lower than that of fresh rice leaves.Therefore,the optimal microwave drying parameters of rice leaves will provide a basis for the application of microwave technology in the threshing process.

微波干燥粮食可行性探讨

经微波加热后，影响稻米品质的脱支酶活力明显下降，而稻米的食用品质和糊化特性变化不大；稻谷、玉米微波干燥应采用低功率、长流程的干燥工艺，稻谷受热温度不超过50℃。玉米受热温度不超过55℃（种子粮除外）；利用高水分玉米对微波吸收量大、产生热量大的特点，与热风干燥进行组合，预热段采用微波加热可明显缩短加热时间，提高干燥效率。