偏高水分粳稻谷储藏期间粮堆空气特性与品质指标的变化

为了寻找偏高水分稻谷低温短期储藏期间的评价指标，本研究基于平衡水分方程和牛顿拉弗逊迭代方法分析了高大平房仓粳稻谷储藏期间粮堆各层空气相对湿度（RH）和湿球温度的变化，并分析它们的积累值与大米热特性、热机械特性、脂肪酸成分及外观品质指标的关系。结果表明，冬季入仓的含水率15.3%的粳稻谷在163 d储藏期间，当粮堆平均温度由8.3 ℃增加到22.9 ℃，一、二、三、四层的RH由75.1%分别增加了3.6%、3.0%、2.9%、2.9%，湿球温度由6.2 ℃分别增加了15.21、13.57、13.47、13.29 ℃，显示粮堆没有虫、霉菌危害。由DSC测定的米粉淀粉糊化温度保持不变。混合试验仪分析表明，随着稻谷储存时间由45 d增加到213 d，米粉团发育和稳定时间、回生扭矩逐渐增加，而酶解速率降低。GC-MS分析表明稻谷在213 d储存期间，重要种类脂肪酸成分所占比例不变。外因指标中粮堆最高积温、最高温度对应的湿球积温；内因指标淀粉糊化峰值温度、面积及高度，米粉团发育与稳定时间、淀粉糊化峰值扭矩、回生扭矩及酶解速率，脂肪酸成分C_14:1、C_14:0、C_20:5n3、C_20:3n6、C_20:2、C_20:1、C_24:1、C_24:0，以及大米外观品质指标整精米率、小碎米率、籽粒尺寸均可作为偏高水分粳稻谷低温储藏的评价指标。

Changes in Intergranular Air Properties of Grain Bulk and Quality Parameters in Japonica Paddy with Slightly High Moisture during Storage

In order to evaluate the quality parameters for short-term stored paddy with slightly high moisture, this study determined the changes in intergranular air relative humidity (RH) and wetbulb temperature of grain bulk with an equilibrium moisture model and Newton-Raphson method, and analyzed the effect of their accumulation amount during storage on thermal and thermo-mechanical properties, and lipid components, and appearance quality indexes in milled rice. The japonica paddy with 15.3% MC was put into warehouse in winter and stored for 163 days, when the average dry temperature in bulk increased from 8.3 to 22.9°C, the average RH in bulk layer 1, 2, 3, and 4 respectively increased 3.6%, 3.0%, 2.9%, and 2.9% from 75.1%, and wetbulb temperature respectively increased 15.21, 13.57, 13.47 and 13.29 °C from 6.2 °C, showing no damage from stored insects and fungi. The gelatinization peak temperature of rice flour measured by DSC remained unchanged. A Mixolab analysis showed, during paddy storage from 45 to 213 d, dough development time and stability time, and starch setback torque gradually increased, but enzymatic speed decreased. GC-MS analysis showed the percent of the main fatty acid species kept unchanged during 213 d paddy storage. External indexes like accumulation of grain bulk maximum temperature, and accumulation of wetbulb temperature corresponding to bulk maximum temperature, and internal indexes such as the temperature, area and height of rice flour gelatinization peak measured by DSC, and dough development time and stability time, gelatinization peak torque and enzymatic speed in rice flour measured by a Mixolab, and fatty acid components (C_14:1, C_14:0, C_20:5n3, C_20:3n6, C_20:2, C_20:1, C_24:1, C_24:0), as well as rice appearance quality indexes like head rice percentage, small broken kernel rate, and kernel size could be used as the evaluation indexes for the low temperature storage of a japonica paddy with slightly high moisture.