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Today, an individual would be hard-pressed to find any science field that does not employ methods and instruments based on the use of fine focused electron and ion beams. Well instrumented and supplemented with advanced methods and techniques, SEMs provide possibilities not only of surface imaging but quantitative measurement of object topologies, local electrophysical characteristics of semiconductor structures and performing elemental analysis. | 11 The Application of Scanning Electron Microscope SEM to Study the Microstructure Changes in the Field of Agricultural Products Drying Hong-Wei Xiao and Zhen-Jiang Gao College of Engineering China Agricultural University Qinghua Donglu Beijing China 1. Introduction The objective of this part Highlight the significance of microstructure investigation in the field of agricultural product drying or dehydration. It is a common sense that structure of material determines its function. The change of macroscopic properties of materials is caused by the changes of its microstructure. For example a porous structure as a honeycomb would facilitate rapid water diffusion or promote a rapid water uptake during drying or cooking. On the contrary a compact structure or fewer pores at the surface of the product can cause a slower moisture migration during drying or water penetration into the interior during rehydration or cooking. Therefore microstructure investigation can help quantifying product changes during processing and may also improve the understanding of mechanisms and changes in quality factors especially the changes in food texture Aguilera Stanley 1999 Xiao et al. 2009 . For example the pore sizes and the number of pores can significantly influence the texture of food. Smaller number of pores and small sizes led to the dense structure. While larger number of pores and large pore size can cause a decrease of the hardness of the product. 2. The classification of the specific research The objective of this part Through concrete examples to introduce the main content and conclusions of the microstructure investigation in the field of agricultural materials drying. 2.1 Observing the microstructure of the material surface before and after the processing to find out the effect of drying on the product microstructure The scanning electron micrographs on the surface of fresh and dried samples can be used to analyze the microstructure changes during drying or dehydration .
