Application of electrical bio-impedance for the evaluation of strawberry ripeness

Electrical bio-impedance measurements were conducted on local strawberry fruits. A non-destructive device was designed to obtain the impedance spectrum of the whole fruit. Four electrical variables were tested: low frequency resistor R-0 (related to extracellular resistances), the high frequency resistor R-infinity(related to intracellular resistances), and constant phase element (magnitude and phase, related to the membrane capacitances and heterogeneity, respectively). In parallel with the electrical bio-impedance measurement, color and firmness were correlated to the ripeness stage. The results indicated that the strawberries at the highest stage of ripeness had significantly lower constant phase element and R-0 values.