Image analysis of kimchi cabbage penetrated with brine and seasoning using a serial block face scanning electron microscope and energy dispersive X-ray spectroscopy

Changes in the shape and composition of kimchi cabbage cells due to brine and seasoning penetration were observed by serial block-face (SBF)-scanning electron microscopy (SEM) imaging and energy dispersive X-ray spectroscopy (EDS). Raw kimchi cabbage (RKC), unfermented kimchi (UKC), and fermented kimchi (FKC) were prepared as samples. Given the osmotic pressure caused by salt, the cell sizes of UKC and FKC were reduced compared to those of RKC and transformed into a thin and elongated rectangular shape. The volume rendering protocol of the SBF-SEM equipped with an ultramicrotome successfully provided a 3D representation of the kimchi cabbage tissue shape. EDS analysis revealed that the lowest C concentrations and the highest Na and Cl concentrations were found in the cell walls of FKC. This study expands the application of SBF-SEM and EDS to acquire basic data on internal changes and material transfer within kimchi cabbage during kimchi manufacturing.