Nondestructive Electrical Impedance Analysis in Fruit: Normal Ripening and Injuries Characterization

Electrical impedance was measured nondestructively in apples (Malus domestica) and tomatoes (Lycopersicon esculentum) over the frequency range 20 Hz-1 MHz. Raw data conform to a single time constant model. Fruit classification and data interpretation are based on the analysis of four derived parameters: low-frequency resistance R, high-frequency resistance RL, constant phase angle Φ, and characteristic frequency f0. The most sensitive parameters to ripening and injuries have proven to be low-frequency resistance and constant phase angle.