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Studies on fissure caused by moisture adsorptio in rough rice

糙米吸湿裂隙的研究

基本信息

批准号：
07660334
负责人：
BEKKI Eiji
金额：
$ 1.47万
依托单位：
Hirosaki University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07660334/
关键词：
fissure adsorption rough rice brown rice rate of adsorption adsorption isotherm water vapor pressure adsorption potential 平衡相対湿度吸-脱湿等温線線膨張率水分拡散係数平衡湿度

项目摘要

Experiments in 1995 utilized a microscopic CCD camera set inside an air oven with temperature and humidity controls purchased under the grant-in-aid program for scientific research. The fissuring behavior of a brown rice kernel in an adsorptive environment was recorded in a video-casette tape using the said camera. The video tape was replayd and on a TV screen the exact time when fissure started and developed was determined. Air conditions in the oven were varied at 80,85,90 and 95% humidity and temperatures of 10,20, and 30ﾟC.The occurrence of fissure were : none in grain with 17.3% moisture, few in grain with 15.3% moisture at 30ﾟC-95% RH,great in overdried grain (12.7% moisture), and greatest in excessively dried grain (10.7% moisture) at all temperature levels and above 85% RH.Majority of overdried grains suddenly fissured in the central part and rapidly extend to the outer part after 1 to 2 hours from the start of drying.The cause of fissure were done using the same oven in the 1996 experiments. In desorption, fissure occurred from 40ﾟC and above. In adsorption when grains were exposed to near saturated air, fissure did not occur in grains with 20.2% moisture, while the rate of occurrence increased with a decrease in initial moisture content, and heavy occurrence in overdried grains (12.7% moisture) at all temperature levels. Adsorption isotherms for 10,20,30 and 40ﾟC were drawn from which grain equilibrium moisture content were given at 40 to 95% RH.The results discussed the relationship of fissuring to : grain expansion and contraction, rate of desorption and adsorption, and adsorption potential. Rice expansion-contraction and lateral-longitudinal ratios were unique among elastic bodies. Adsorption and desorption were caused by the difference in water vapor pressure. The driving force is the adsorption potential which depends on humidity.

1995年的实验使用了一台显微CCD摄像机，该摄像机安装在一个空气烘箱内，带有温度和湿度控制装置，这是根据科学研究补助金方案购买的。用该摄像机记录了糙米在吸附环境中的裂纹行为。录像带被重播，并在电视屏幕上确定了裂缝开始和发展的确切时间。烘箱中的空气条件在80、85、90和95%的湿度和10、20和30 ℃的温度下变化。裂缝的发生率为：在30 ℃ ~ 95%RH条件下，水分17.3%的籽粒中无，水分15.3%的籽粒中很少，过干籽粒中大量（12.7%水分），在过度干燥的谷物中，（10.7%水分）在所有温度水平和85%以上大多数过干的谷粒在干燥开始后1 - 2小时，在中部突然裂开，并迅速扩展到外部。在1996年的实验中使用了相同的烤箱。在解吸过程中，40 ℃以上开始出现裂隙。在近饱和空气中吸附时，含水量为20.2%的谷物不产生裂纹，而裂纹的发生率随初始含水量的降低而增加，过干谷物（含水量为12.7%）在各温度水平下均出现裂纹。根据10、20、30和40 ℃的吸附等温线，给出了40 ~ 95%RH下的平衡含水率，讨论了谷物膨胀收缩、解吸吸附速率和吸附势与裂纹的关系。在弹性体中，水稻的伸缩率和横纵比是唯一的。吸附和解吸是由水蒸气压差引起的。驱动力是取决于湿度的吸附势。