稻谷低温低湿干燥特性与水分迁移分析  

Analysis of drying characteristics and moisture migration for paddy rice under low temperatures and low relative humidities

作　　者：汪楠[1] 邵小龙[1] 时小转 沈飞[1] 宋伟[1] 

机构地区：[1]南京财经大学食品科学与工程学院/江苏省现代粮食流通与安全协同创新中心/江苏高校粮油质量安全控制及深加工重点实验室,江苏南京210023

出　　处：《食品工业科技》2017年第5期114-119,共6页Science and Technology of Food Industry

基　　金：公益性行业(粮食)科研专项(201513002-05);国家自然科学基金项目(31201443);江苏高校优势学科建设工程资助项目(PAPD)

摘　　要：对初始含水率18.9%~29.6%的稻谷进行低温低湿薄层干燥,基于模型拟合、干燥时间和有效水分扩散系数的计算,研究稻谷初始含水率和温湿度因素对其表观水分扩散特性的影响,通过核磁共振技术探究前者内在水分动态。结果表明:在低温低湿条件下干燥温度越低,除湿对缩短稻谷干燥时间的效果越显著。Page模型拟合效果理想,参数k和n能较好地用实验变量所建立的回归方程描述。稻谷的有效水分扩散系数Deff在3.0697×10-10m2/s到5.0369×10-10m2/s范围内,MC0、T和RH对其有极显著的影响(p<0.01)。同时,核磁数据反映出干燥过程中,稻谷内表征"结合水"的A21峰面积和束缚水的A22峰面积降低显著,自由水的A23峰面积变化较小,含水率降至14.5%~16.5%范围时束缚水的信号峰消失。连续称重法结合LF-NMR技术能够有效分析稻谷低温低湿干燥过程中水分扩散和状态转化的规律。The thin-layer drying experiments of paddy rice with different initial moisture contents（ 18.9% -29.6% ）were conducted under low temperatures and low relative humidities. Mathematical models, drying duration and effective moisture diffusivity were used to investigate the effects of initial moisture content, drying temperature and air relative humidity on the external moisture diffusion characteristics of paddy rice. LF-NMR was adopted to analyze the internal moisture dynamic of kernels during the drying process of paddy rice. The results showed that the lower drying temperature, the more significantly humidification could shorten the durations of paddy rice.The Page model could fit the drying curves of paddy rice very well, and the mathematical expressions for parameters k and n could be better described by the experimental variables. Besides, the effective moisture diffusivity of paddy rice was high significantly （p 〈 0.01 ）influenced by MCo, T and RH, and Do, varied from 3.0697 ×10^-10m^2/s to 5.0369×10^-10m^2/s.During the whole drying process of paddy rice,the data of LF-NMR indicated that both the A21 peak area representing for ＂ bound water＂ and A22 peak area representing for capillary water decreased significantly, while the A23 peak area representing for free water kept steady. When the moisture content of paddy rice was decreased to 14.5 %- 16.5 % , the LF-NMR signal peak of capillary water disappeared.We can combine the continuous weighing method and LF-NMR technology to effectively analyze the laws of moisture diffusion and moisture state transformation during the low-temperature and low-relative humidity drying process of paddy rice.

关 键 词：稻谷 低温低湿 干燥特性 有效水分扩散系数 核磁共振 

分 类 号：TS201.1[轻工技术与工程—食品科学]