A noninvasive method for detecting frozen injuries in potatoes based on electrical impedance spectroscopy

Abstract

To simplify the application of electrical impedance spectroscopy, the characteristic points were explored for noninvasive determination of the freezing damage in potatoes. Impedance experiments were conducted on the potato samples at room temperature (20°C), 0, −4, and −20°C. Samples of fresh, frozen, and freeze–thawed samples were analyzed. The results show that the shapes of the impedance spectroscopies were different in each of these samples. The characteristic points Zextra, Zintr, and Zcyt from electrical impedance spectroscopy are proposed to indicate the freezing damage level. The Zcyt value was considerably different for each state (1,939; 25,130; and 43 Ω, respectively). This indicates that Zcyt is a useful index for freezing damage classification and that Zcyt could indicate cell structure changes in thawed samples. Practical applications The morphological characteristic points of electrical impedance spectroscopy were used to evaluate the freezing injury of potatoes. This method provides a novel approach to study the changes in biological tissues. The method of using characteristic points is more convenient and effective than with an equivalent circuit. The Zcyt value could be used for detecting freezing injury in potatoes. Moreover, this method can be potentially applied for quality analysis of agricultural products.