| Budget Amount *help |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 1987: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 1986: ¥2,800,000 (Direct Cost: ¥2,800,000)
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| Research Abstract |
The object of this study is nondestructive electrical inspection of internal quality of fruits and vegetables. On-line real time system which can measure vector impedance of fruits and vegetables and analyze the dielectric properties has been developed. Obvious differences in dielectric properties were distinguished between fresh and spoiled or damaged fruits in the range of 10Hz to 13MHz. According to rot or damage, resistance of fruits, impedance, and reactance decrease sharply, and capacitance and dielectric loss factor increase. Among these impedance parmeters, correlation between resistance Rs and freshness or maturity is the most obvious in nondestructive measurement. Thus, the freshness of fruits can be measured nondestructively and contactively by resistance Rs.
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
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The most difficult problem of inner quality measurement by dielectric property is that the measured values of impedance parameters are influenced by the shape and the size of fruits. To solve this problem, we tried to measure the dielectric properties of fruits by comparison with those of water. For example, when we sink fruit into water in a container which has electrodes on both sides , if the specific resistance of fruit is greater than that of water, the resistance between electrodes increases by comparison with the value before sinking. If the specific resistance of fruit is lower than that of water, the resistance between electrodes decreases. The magnitude of change depends on the size and shape of the fruit but the direction of change does not depend on the shape or size of the fruit or vegetable. Accordingly, we can separate fruits by specific resistance, preparing water which has a threshold value of specific resistance. By this metod, we can easily measure the quality of fruits and vegetables which have complex shapes. Less
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