Electrical properties of banana fruit were studied in order to develop a rapid and non-destructive assessment method and to control its ripening treatment. A 5 V sine wave AC power supply and a rectangular parallel plate capacitor sample were used to span the difference in capacitance caused by the introduction of a banana fruit between the plates. To remove the effect of air gap between the plates, an equivalent capacitor was derived. The correlation between dielectric constant and quality parameters of banana fruit was investigated. The dielectric constant of banana fruit decreased as a result of the ripening treatment. Experiments indicated that the best frequency of sine wave that can predict the level of ripeness was 100 kHz. The coefficient of determination (R-2) of ripeness level prediction was obtained 0.94 at this frequency. This method can confidently predict the ripeness level of banana fruit. (C) 2011 Elsevier Ltd. All rights reserved.