Discriminating Natural and Ethephon-Induced Ripening in Bananas via Electrochemical Impedance Spectroscopy (EIS)

Abstract

This paper presents a non-invasive approach for monitoring the ripening process and detecting artificial ripening methods in bananas (Musa paradisiaca) using Electrical Impedance Spectroscopy (EIS). While Ethephon is widely used to accelerate ripening, distinguishing between naturally and chemically ripened fruit remains a challenge for food safety and quality control. In this study, impedance measurements were conducted daily over a 7-day period across a frequency range of 50 Hz to 1 MHz using flexible surface electrodes to maintain tissue integrity. The experimental results demonstrated that samples treated with 1000 ppm Ethephon exhibited a stable and progressive increase in real impedance (Zreal), peaking at approximately 60,000 Ω by Day 6. Conversely, samples treated with a 2000 ppm overdose showed an initial impedance surge followed by a significant "collapse" to 30,000 Ω by Day 7, indicating early senescence and membrane degradation. To quantify these physiological changes, an equivalent circuit model was implemented, showing high concordance with experimental Nyquist plots. The findings confirm that EIS parameters, particularly charge transfer resistance and Warburg diffusion, serve as reliable, non-destructive indicators for fruit quality assessment and the detection of forced ripening in the agrifood supply chain.