Study on the Correlation Between Water Content of Peanut Kernel, Water Phase State and Electrical Impedance Spectrum Parameters

Abstract

In an effort to develop a novel approach for detecting the moisture content of peanut kernels and enhancing detection efficiency, this study employed electrical impedance technology, and low-field nuclear magnetic resonance technology to investigate the relationship between water phase state, impedance values (real and imaginary components), phase angle, and moisture content of peanut kernels ranging from 10.4% to 41.0%. The findings revealed that water in the peanut kernel mainly gathered in the middle part of the two cotyledons. As the moisture content escalates from 10.4% to 41.0%, the ratio of free water to bound water decreased from 6.3:1 to 1.9:1. The highest correlation coefficient was observed between the real part of impedance and moisture content, whereas the phase angle exhibited the lowest correlation coefficient. The real part of impedance emerged as the most effective impedance spectrum parameter for modeling the moisture content of peanut kernels. Furthermore, the relationship between electrical impedance spectrum parameters, and water content was found to be frequency-dependent, with the highest correlation between the real part of impedance and water content observed in the frequency range of 1–4 MHz, yielding an R² value of 0.986. These research outcomes offer valuable insights for advancing the development of rapid and nondestructive moisture content detection technologies for peanut kernels utilizing resistance methods.