微波干燥粮食初探

Exploration of Drying Grain by Microwave

微波加热干燥物料与热空气加热的机理不同 ,微波加热对高水分粮食和具有坚硬外壳物料的干燥效果比热空气干燥效果好。国外有许多有关报导 ,并研制出大型粮食微波干燥机。国内有关资料很少 ,玉米、稻谷属于不易干燥的粮食品种 ,用微波炉对其进行干燥 ,实验结果表明 ,经微波加热后影响稻米品质的脱支酶其活力明显下降 ,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 ,予热段采用微波加热可明显缩短加热时间 。

The mechanisms of drying materials with microwave and with hot air are different.The effect of microwave is better than hot air in drying high moisture grains and materials with hard shell.Large-scale microwave grain dryers have been developed in foreign countries. However,there are rare studies on this subject at home.Maize and rice both are not easy dried.We have dried rice and maize with microwave oven.The activity of debranching enzyme in rice dried with microwave decreased greatly,but its cooking quality and gelatinization propery changed little. For drying rice and maize with microwave,the drying technology of low-power and long-time was used. The proper drying temperature is below 50℃ for rice and below 55℃ for food use maize.For maize with high moisture,pre-drying with microwave and then drying with hot air can apparently shorten heating time and enhance drying efficiency.