The Application of Scanning Electron Microscope (SEM) to Study the Microstructure Changes in the Field of Agricultural Products Drying

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.