Nondestructive Measurement of Internal Quality of Apples by Dielectric Properties

Differences in dielectric properties of various quality of apples were measured nondestructively by use of LCR instrument, round parallel-plate electrode, personal computer and the software of nondestructive measurement of dielectric properties of fruits. The results show that from 5 kHz to 100 kHz in frequency, the equivalent impedance of spoiled or damaged apples is less than that of intact apples, but the measurement results may be affected by the excursion of frequency. The dielectric constant of spoiled or damaged apples is more than that of intact apples, and from 33 kHz to 100 kHz in frequency, the dielectric constant is not affected by the excursion of frequency basically. The change of loss factor is anomalous. It is feasible that the dielectric constant can be adopted to distinguishing the internal quality of fruit.