Electrical characterization of milk samples by electrical impedance spectroscopy (EIS)

Abstract

This work presents a study of electrical impedance spectroscopy (EIS) as an alternative to characterize milk, aiming to develop an analysis methodology with advantages over other methods, such as portability and low cost. The behavior of the electrical impedance module, the real part and the imaginary part (reactance), and the derived quantities such as admittance, phase and diffusion coefficient (D) were also analyzed and will be discussed. Comparisons of the measured spectra with theoretical models of equivalent circuits were carried out in order to understand the electrical behavior of the samples. Understanding this electrical phenomenon will help in the development of future analysis methodologies. The results indicated that milk is a solution with predominantly resistive behavior with an estimated resistance value of 500 Ohms, with low storage load due to low viscosity. The best-fitting equivalent circuit was a mixed RC model consisting of a series resistor coupled with a resistor in parallel with a capacitor.