Electrochemical Impedance Spectroscopy as an Alternative to Determine Dielectric Constant of Potatoes at Various Moisture Contents

Abstract

The dielectric (DE) properties, specifically the DE constant (ε') and loss factor (ε''), were measured for vacuum-dried and freeze-dried potato samples at a microwave frequency of 2.45 GHz over a range of different moisture contents (MCs) using a DE probe and also a 2-probe electrochemical impedance spectroscopy (EIS). Third-order polynomial models (ε' = f₁(MC); and ε'' = f₂(MC)) at room temperature were developed for regression analysis. Additionally, at various temperatures (T), biphasic 3rd-order polynomial models (ε' = f₁(MC, T); and ε'' = f₂(MC, T)) were obtained to determine ε' and ε'' as a function of MC and T using measured data. The vacuum-dried potato sample showed a good fitness of ε' and ε'' (R² = 0.95 and 0.96, respectively) to the regression model with the range of MCs from 18% to 80% (w/w), while the freeze-dried potato sample showed a good fitness of ε' and ε'' to the 1st-phase regression model with MC < 50% w/w (R² = 0.95 and 0.96, respectively) and the 2nd-phase regression model with MC > 50% w/w (R² = 0.94 to 0.96). EIS measurements were also used to obtain correlation impedances for ε' and ε'' determined by the DE probe method. The resulted regression analysis meets the demands for simple, rapid, and accurate assessment for transient values of ε' and ε'' of food products during dehydration/drying processes. The EIS method was verified to be a successful alternative to direct measurements of ε' and ε''.

Food Preservation Technology at Subzero Temperatures: A Review

“…Therefore, the electrochemical impedance spectrum of a food provides information about changes in its microstructure. In fact, many studies have used EIS to show the microstructure of foods during dehydration (Ando et al, 2014;Chee et al, 2014). EIS has also been used to detect the onset of spoilage during the aging of meats (Damez et al, 2008;Guermazi et al, 2011;Niu and Lee, 2000;Oliver et al, 2001;Zhang et al, 2011).…”

Measurement and Analysis of Dielectric Properties of Agricultural By-product Powders in Microwave Frequency Range

“…In the past few decades, many scholars have focused on the requirements of thermal processing, storage, preservation, sterilization, grading and nondestructive testing of agricultural media. Different technical methods were applied to study the dielectric properties and influencing factors of agricultural media [1][2][3][4] . The research results strongly promoted the microwave thermal processing application and product development of agricultural media.…”

Dielectric properties of the small granular agricultural products in the microwave frequency band

“…), the main research objects were rice, seeds, corn, wheat, vegetables and fruits (Nelson 2005, Nelson et al 2012, and he summarized the research works in 2015 (Nelson 2015). In addition, Chee analysed the dielectric constant and its relationship with the moisture constant of freeze-dried potato chips at a frequency of 2.45 GHz using the electromagnetic spectral technique (Chee et al 2014). Sipahioglu measured the dielectric properties of bananas at frequency 2.45 GHz and within a temperature range from 5-130˚C to determine that the dielectric loss factors of vegetables and fruits first decreased and then increased with the temperature (Sipahioglu et al 2010).…”