Electrical impedance estimation for apple fruit tissues during storage using Cole-Cole plots

The objective of this study was to analyze Cole-Cole plots obtained from electrical impedance measurements in apple fruits during storage. We evaluated the changes in Cole-Cole plots for five cultivars. The coordinates at the top of the circular arcs of the Cole-Cole plots were grouped for each cultivar. The anisotropy of the electrical impedance properties of fibers from these samples was examined. The length of the coordinates at the top of circular arcs of the Cole-Cole plots from the origin of samples decreased during 1-4 weeks storage due to a decline in the integrity of cell membranes. These non-uniform electrical properties were caused by variations in the cell size, which differed for each cultivar and changed during storage. We showed that Cole-Cole plots could be applied as a method to assess the integrity of the cell tissues of apples during storage.