Quantification of PEF-induced membrane permeabilization in carrot tissue using electrical impedance spectroscopy and Cole–Cole modeling

In this study, PEF-induced membrane permeabilization in carrot ( Daucus carota L.) tissue was systematically investigated using electrical impedance spectroscopy (EIS) combined with Cole–Cole equivalent circuit modeling. Carrot samples were treated at electric field strengths of 0.25–1.0 kV/cm and specific energy inputs of 0.5–20 kJ/kg. Impedance spectra (100 Hz–1 MHz) were acquired before and after treatment and fitted using a Cole–Cole model incorporating double-layer capacitance to account for electrode–tissue interfacial polarization. PEF treatment caused a pronounced reduction in β-dispersion, indicating progressive membrane permeabilization, while only minor changes were observed in the α-dispersion region associate with electrode–tissue interfacial polarization effects. Model analysis revealed a strong, nonlinear decrease in the resistance difference ( R 0 − R ∞ ) and relaxation time (τ) with increasing PEF intensity, primarily governed by electric field strength. Tissue pseudo-capacitance increased by several orders of magnitude at high field strengths, whereas the Cole exponent (nₚₜ) decreased markedly, reflecting a transition from capacitive to predominantly ohmic behaviour. These electrical parameters, particularly the resistive and time-related circuit elements, showed strong correlations with the cell disintegration index (Zₚ) and with microstructural changes observed by scanning electron microscopy. Overall, the results demonstrate that combining Cole–Cole modeling with Zₚ analysis offers a robust, non-destructive approach for monitoring PEF-induced structural changes in plant tissues, providing valuable guidance for optimizing electroporation-based food processing applications. • PEF-induced membrane permeabilization was quantified by EIS and Cole–Cole modeling. • Tissue electrical changes dominated impedance response over electrode–tissue effects. • Resistance parameter R₀–R∞ sharply decreased with increasing PEF intensity. • Relaxation time τ strongly reflected progressive loss of membrane integrity. • R₀–R∞ and τ showed near-perfect inverse correlation with Zₚ ( r ≥ −0.996). • Zₚ was validated as a robust macroscopic indicator of cell membrane permeabilization.