design, development and test of apparatus to measurement of electrical resistance and impedance of fruit

electrical properties of fruits are accepted indicators for detecting fruit quality. electrical resistanceone reluctance can detect quality factors and are sensitive to variations in the concentration and stateof water. therefore, these properties can be associated with maturity, damage, overripe condition,decay or other quality factors. in most of previous research on electrical resistance and impedanceof fruits, sensors pushed into the fruit to measure electrical resistance of the sample between twoelectrodes. needle type electrodes usually are used which results in damages to the fruit. thus inevery tests, samples should change. in this experiment, especial electrodes for measuring electricalresistance were developed and used which did not damage the fruit. electrical sensors for electricalresistance measurement consisted of two copper plates. fruit sets between two plate electrodeswhere constant force was applied on it. the overall construction of the apparatus was made up ofthe following main components: lcr meter, load cell, indicator, base, frame, and probes. redapples were used in this experiment. electrical resistance measurements were performed at twofrequencies; 120 hz and 1 khz. water loss of the whole fruit also contributed in decreasing themobilization of ions, thus, increasing of electrical resistance of the ripen fruit. the results indicatedthat the relationship between the electrical resistance and the weight loss, during the storage period,was also investigated. the results indicated that, the electrical resistance decreases by third degreeequation and the weight of apple decreases linearly with increase in storage period.