Water Diffusion Characteristics and Microstrcture of Blueberry During Hot-air Drying
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摘要: 为了研究蓝莓热风干燥过程中水分扩散特性和微观结构的变化规律,采用电热恒温箱在50、65和80 ℃的条件下对蓝莓进行热风干燥试验,应用核磁共振(nuclear magnetic resonance,NMR)和微观电镜扫描仪(scanning electron microscope,SEM)技术,测定蓝莓在干燥过程中水分迁移和内果皮微观结构的变化。结果表明:干燥过程改变了蓝莓中水分迁移特性,自由度高的水分向自由度低的迁移。干燥温度和干燥时间两个维度影响干燥效果,干燥速率随干燥温度的升高渐增。50、65、80 ℃的温度下干燥时间分别为50、18、7.5 h。干基含水率与核磁共振信号幅值之间存在显著的线性关系(y=113.99x+5728.6,R2=0.9901,p<0.01)。随干燥过程中水分的散失,蓝莓果干发生皱缩现象,微观上为细胞壁微丝排列由紧密有序变得松散无序。本研究为蓝莓果干干燥过程中水分迁移和组织微观结构的变化规律提供数据参考。Abstract: The objective of this study was to investigate water diffusion characteristics and microstructure of blueberry at different temperatures during hot-air drying process, which was respectively 50, 65, 80℃. Using nuclear magnetic resonance (NMR) and microscopic electron microscopy (SEM) techniques, water transport and micro-structural changes in the inner pericarp of blueberries during drying were analyzed. Results showed that moisture distribution was changed in drying process and the moisture with high degree of freedom moved to the moisture with low degree of freedom. Temperature and time were two main aspects during hot-air drying. Drying rate was accelerated with the rise of drying temperature. Drying time at 50, 65 and 80℃ were 50, 18 and 7.5 h, respectively.Water contents in dry base and nuclear magnetic resonance signal amplitude were followed significant linear regression (y=113.99x+5728.6, R2=0.9901, p<0.01).With loss of moisture during hot-air drying process, shrinkage of blueberry occurred and microstructure changed. Microscopically, cell wall microfilaments were arranged from tightly ordered to loosely disordered. This study provided data reference for the changes of water migration and microstructure in the drying process of blueberry fruit.
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Keywords:
- blueberry /
- hot-air drying /
- nuclear magnetic resonance /
- water diffusion /
- micro-structure
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