基于低场核磁技术的不同花期金银花红外干燥过程中的水分变化  

Analysis of Moisture Changes in Flos lonicerae at Different Flowering Stages during Infrared Drying Using Low-field NMR

作　　者：杜利平[1,2] 崔莉[1] 赵恒强[1] 闫慧娇 王涛[1] 王晓[1] 

机构地区：[1]山东省中药质量控制技术重点实验室山东省分析测试中心,山东济南250014 [2]山东农业大学食品科学与工程学院,山东泰安271018

出　　处：《现代食品科技》2017年第9期189-194,201,共7页Modern Food Science and Technology

基　　金：国家自然科学基金面上项目(81473298);山东省科技发展计划项目(2014GSF119031);山东省科学院先导专项

摘　　要：本文研究了不同花期金银花(三青期、大白期和全花期)红外干燥过程中的水分分布及状态变化。不同花期金银花在45℃条件下进行远红外干燥,应用低场核磁共振技术(LF-NMR)分析金银花中水分随时间的迁移变化情况。结果表明,不同花期的金银花中均含有三种状态的水:结合水、半结合水和自由水,其含量为:半结合水>结合水>自由水;三青期金银花的结合水和自由水含量高于大白期和开花期,半结合水含量相对低于大白期和开花期;金银花干燥过程中,不同状态的水也呈现出不同的变化规律,半结合水含量逐渐减小,结合水含量先减少后增加,干燥过程改变了金银花内部水分分布状态和水分含量,不同状态的水分之间会发生一定的相互转化,三青期金银花中部分结合水在干燥初期流动性变大,后期流动性变小,大白期金银花结合水流动性持续变小。干燥过程中金银花水分含量与半结合水的峰面积、总峰面积均有较高的相关性(R2>0.9),LF-NMR技术为金银花中水分分布及变化规律提供了直观的参考依据。Changes in water distribution and water states in Flos lonicerae during infiared drying were assessed at three different flowering stages （three green period, large white period, and golden flowering period）. The three E lonicerae samples were subjected to far-infrared radiation at 45℃, and low field-nuclear magnetic resonance （LF-NMR） spectroscopy was employed to evaluate differences in water mobility and distribution. Three water states - bound water, immobilized water, and free water - were detected in E lonicerae samples at different flowering stages, with volume fraction decreasing in the order： immobilized water 〉 bound water 〉 free water. The proportions of free water and bound water in the E lonicerae sample at the three green stage were higher than those in the F. lonicerae samples at the big white and whole flowering stages, and the immobilized water content of the E lonicerae sample at the three green stage was lower than those of the samples at the big white and whole flowering stages. During the drying process, different forms of water also exhibited different patterns of change; the immobilized water content decreased gradually, while the bound water content decreased at first and then increased. The drying process changed the internal water distribution and water content of the E lonicerae samples, and interconversion between different forms of water occurred. The fluidity of the bound water increased during the initial period of drying, before decreasing during the final stages of the drying process. However, the fluidity of the bound water of the sample at the large white stage continued to decrease throughout the drying process. During the drying process, the water content ofF. lonicerae was highly correlated with the peak area of immobilized water and the total peak area （R^2 〉 0.9）. Thus, the NMR technique used in this study provided an intuitive basis for the analysis of water distribution and variation in F. lonicerae at different flowering stages.

关 键 词：金银花 红外干燥 低场核磁共振技术(LF-NMR) 

分 类 号：O657.2[理学—分析化学] TS218[理学—化学]