1988 Volume 50 Issue 6 Pages 99-107
The object of this study is nondestructive electrical inspection of internal quality of fruits and vegetables the freshness of which is very important for consumers. On-line real time system which can measure vector impedance of fruits and vegetables and analyze the dielectric properties has been developed. Impedance, capacitance and resistance of fruits and complex permittivities of the sarcocarps were measured in the frequency range from 10Hz to 13MHz both nondestructively and destructively. Obvious differences in dielectric properties were distinguished between fresh and spoiled or damaged fruits in this range of frequencies. According to rot or damage, parallel equivalent resistance of fruits, impedance, series equivalent resistance and reactance decrease sharply, and series equivalent capacitance and dielectric loss factor increase. Among these impedance parameters, correlation between series equivalent resistance and freshness or maturity is the most obvious in nondestructive measurement. Thus, the freshness of fruits can be measured nondestructively and contactively by series equivalent resistance.
Next, we tried noncontacting measurement of resistance of fruit by capacitive connection. It became clear that if the fruits are spherical and same size, the freshness can be measured nondestructively and noncontactively.
