Electrical Impedance Spectroscopy in Agricultural Food Quality Detection

ABSTRACT In this review, the authors summarized analysis methods of electrical impedance spectroscopy (EIS) within agricultural food quality detection (maturity, moisture, stress, and freshness) and determined the basic principle, feature parameter extraction, modeling, and detection mechanism. The results indicated that the parameters extracted using the impedance spectrum can reflect the state of agricultural food, and the dimension, heterogeneity, detection location, and ambient temperature of samples substantially influence measurement precision. However, the following two problems limit further application: the extraction of electrical parameters of different states and the individual differences in samples. Extraction methods include the equivalent circuit model, characteristic frequency, and Cole‐Cole function. Because currents of different frequencies flow through tissues in different routes, the characteristic frequency method can express cell information changes. The fusion parameters representing the product's quality can be obtained using proper selected‐frequency extraction. Eliminating the individual heterogeneity of agricultural products is the remaining technical limitation. A preliminary study shows characteristic points on the EIS curve could reduce individual differences. Owing to EIS's advantages of being rapid and non‐destructive, further research should investigate eliminating individual impact via the extraction of the characteristics of EIS.