Abstract:
Nondestructive physical tests can be considered as recent trends for quality evaluation
of a
gricultural products. Required information on postharvest quality of fruits and
vegetables makes it possible to use their electrical properties as a novel method for
nondestructive quality evaluation purposes. In this study, the electrical resistance of
ha
rvested apple fruits (Golden Delicious variety) was nondestructively measured by
developing and employing special plate electrodes using a load cell to adjust the force
holding the samples between two electrodes. Electrical resistance measurements were
per
formed at two frequencies; 120 Hz and 1 kHz. Precise fruit weight was also measured
along with electrical resistance measurements. The relationship between the electrical
resistance and the weight loss was investigated during the storage period. The experi
ment
ran for a total of 24 days. Results showed that in the 15 initial days of experiment, the
electrical resistance decreased by increasing the storage period. But with further increase
in the storage period, the electrical resistance also increased. The
loss of the fruit moisture
content, during the early stage of storage, may be attributed to the decrease of the fruit
electrical resistance. However, as the stored apples lost more moisture, the concentration
of ions, in soft tissues of samples, highly inc
reased and this could be responsible for the
increase of apple electrical resistance during the final days of the experiment.
Keywords:
Electrical resistance,
Electrical properties of apple, Plate electrode, Storage
period of apple, Weight loss.
