An electrical discrimination method for rot in fresh cut apples using Cole–Cole plots

We evaluated the electrical properties of cut apples with and without rot incidence. Cole–Cole plots were prepared from the frequency characteristics of the electrical impedance of sample tissues and used for the analysis of the rotten samples. The coordinates at the top of the circular arc in Cole–Cole plots of all samples showed a linear regression, and it was estimated that the coordinates were influenced by extracellular fluid resistance. The coordinates of the samples were grouped according to the absence or presence of rot. It was deduced that the decrease in the position of the coordinates was caused by metabolites produced by multiplied bacteria in extracellular fluids. We showed that the Cole–Cole plot coordinates have potential as a simple, low-cost, and quantitative marker to aid in the rapid discrimination of rot in cut apples. This approach could be developed for use in the detection of postharvest disease during fruit processing, aiding in the construction of a high-quality supply-chain, and food-safety management.