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

Abstract

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 R0 (related to extracellular resistances), the high frequency resistor R∞ (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 R0 values.