Study of Rough Rice Drying (I)

about Injury and Drying characteristic of Impacted Rough Rice

Abstract

There are considerable injured grains, such as opening glume, cracked glume and hasked rice in the rough rices harvested by the combine. Consequently, the drying speed of rough rice is increased and the problem of the occurrence of cracked rice is come of.
To investigate this problem, the rough rice was impacted by a grain impact testing machine, and the following results were obtained as to occurrence of injured grain, cracked rice and drying characteristic.
(1) The injury of rough rice by the impact is rapidly increased from the impacting speed of about 1, 250m/min. and the correlation between the percent of injury (y₁) and the impact speed (x₁) can be expressed by the following equation: y₁=Cx₁^α, where C and α are constants due to rough rice. But the increase of occurrence of cracked rice is comparatively slack.
(2) The influence of ripeness extent and moisture content to the impact was not recognized as to the rough rice of more than 35 days after heading and so far as the moisture contents are 21-25%.
(3) The more the impacting force increased, the faster the drying speed of impacted rough rice. This proves that the rough rice became easy to dry since the rough rice was injured. The correlation between the change of moisture content (y₂) and the passage of drying time (x₂) can be expressed by the following equation; y₂=Dx₂β, where D and β are constants depend on moisture content of rough rice, impacting speed and condition of drying air. (2<x₂<6 hours)
(4) The injured rough rice not only hastens the drying in proportion to the impacting speed, but also leads to the increase of occurrence of the cracked rice.
As the cracked rice is increased at the speed of impact more than 1, 250m/min., it is necessary to down the drying speed against the rough rices which have the occurrence of many injured grains.