[关键词]
[摘要]
目的 通过对不同初始含水率的大黄在相对湿度20%~85%,温度分别为5、15、25、35℃条件下的吸湿规律进行研究,为大黄安全贮藏水分的控制及合理贮藏提供参考。方法 将大黄药材分别贮藏于温度为5、15、25、35℃,湿度为45%、60%、75%条件下,并于不同时间点取样,以粉末颜色及霉变为指标,确定其安全水分活度(water activity,Aw);并通过静态称量法,得到大黄药材在5、15、25、35℃及水分活度为0.2~0.8的等温吸附数据,采用GAB、Oswin、Smith、Halsey、Henderso、Peleg 6种等温吸附模型进行拟合和评价。结果 大黄的绝对安全Aw为0.5,相对安全Aw为0.6,在5、15、25、35℃下的大黄吸附等温线的类型为“S”型,属于II型等温线,Oswin模型为最佳吸湿等温线拟合模型,模型表达式为:Meq=A[Aw/(1-Aw)B,并由该模型计算得到:5℃下不同初始含水率大黄的绝对安全水分为9.00%、9.59%、8.00%、6.71%和相对安全水分为10.17%、10.89%、9.20%、8.07%;15℃下不同初始含水率大黄的绝对安全水分为8.24%、8.83%、7.24%、5.86%和相对安全水分为9.57%、10.17%、8.59%、7.20%;25℃下不同初始含水率大黄的绝对安全水分为7.17%、7.75%、5.73%、4.70%和相对安全水分为8.72%、9.26%、7.26%、6.25%;35℃下不同初始含水率大黄的绝对安全水分为8.00%、8.45%、6.53%、5.21%和相对安全水分为9.74%、9.85%、8.40%、7.27%。结论 Oswin模型可作为大黄药材贮藏中平衡含水率的预测模型,为大黄贮藏安全水分的控制及科学的养护提供参考。
[Key word]
[Abstract]
Objective The moisture absorption of Rhei Radix et Rhizoma (RRR) with different initial moisture content was studied under the conditions of relative humidity of 20%-85% and temperature of 5, 15, 25 and 35℃, respectively, so as to provide reference for the control of safe storage moisture and reasonable storage of RRR. Methods RRR was stored at temperature of 5, 15, 25 and 35℃ and humidity of 45%, 60% and 75%, respectively. The samples were taken at different time points to determine its safe water activity with powder color and mildew as indicators. The isotherm adsorption data of RRR at 5, 15, 25 and 35℃ and water activity of 0.2-0.8 were obtained by static weighing method and six isotherm adsorption models, GAB, Oswin, Smith, Halsey, Henderso and Peleg, were used for fitting and evaluation. Results The absolute safe water activity and relative safe water activity of RRR were 0.5 and 0.6, respectively. The adsorption isotherms of RRR at 5, 15, 25 and 35℃ were "S" type, which belonged to type II isotherm. Oswin model was the best fitting model and the model expression was:Meq=A[Aw/(1-Aw)B. According to the model, the absolute safe water content of RRR with different initial moisture content at 5℃ was 9.00%, 9.59%, 8.00%, 6.71% and relative safe water content was 10.17%, 10.89%, 9.20% and 8.07%, respectively; The absolute safe water content of RRR with different initial moisture content at 15℃ was 8.24%, 8.83%, 7.24%, 5.86% and relative safe water content was 9.57%, 10.17%, 8.59% and 7.20%, respectively; The absolute safe water content of that at 25℃ was 7.17%, 7.75%, 5.73%, 4.70% and the relative safe water content was 8.72%, 9.26%, 7.26% and 6.25%, respectively; The absolute safe water content of that at 35℃ was 8.00%, 8.45%, 6.53%, 5.21% and the relative safe water content was 9.74%, 9.85%, 8.40%, 7.27%, respectively. Conclusion Oswin model can be used to predict the equilibrium moisture content of RRR in storage, which can provide reference for the control of safe moisture and scientific maintenance of RRR.
[中图分类号]
R283.6
[基金项目]
国家自然科学基金基础科学人才培养基金项目(J1310034);国家中医药管理局全国中药资源普查项目(GZY-KJS-2018-004);全国第四次中药资源普查2018年度第二批外业调查研究(2018PC010)