The Cavendish variety of banana fruits transported from the
Ecuador was used in this experiment. The banana fruits have been
stored at 14 C temperature when transferred. Fifty-eight fingers of
banana were randomly selected from banana bags in a ripening
room of Damirchiloo warehouse located in Karaj city in Iran. The
experiment was carried out at airtight ground-warehouses with
fruits kept at humidity level of 85–88% for 5 days, the time needed
for completing the ripening treatment of fruits. At this site, ripeness
is currently assessed visually by comparing the peel color of
banana with standardized color charts that describe various stages
of ripeness. In trade market, seven ripening stages of bananas are
usually discerned (Fig. 1). Color stage is judged visually using a
chart scale provided by SH Pratt & Co. Ltd (Luton, United Kingdom)
to categorize banana based on its level of ripeness. Stage 7 is not
performed in the warehouse and at the end of stage six the fruits
are transported to the market. On the first day, banana fruits were
at stage 1 and on the fifth day, they were at stage 6. Ethylene gas
with 1000 ppm concentration was treated about 24 h on first
day. It is very important to control temperature, humidity and ethylene
gas concentration in the ripening room.
In order to give a good artificial climacteric rise of banana fruits
during the ripening, electrical impedance measurements wereperformed in the ripening room. The experiments were conducted
in controlled temperature room at 15.5 C. To measure capacitive
properties of banana, a rectangular parallel plate capacitor with
25 cm in length and 10 cm in width was constructed as a standard
hardware instrument. The conductive plates were selected from
aluminum materials because of its consistency which would not
be easily ionized as a factor that will ruin the results of experiments.
The impedance of capacitive sensor was measured by a
voltage divider circuit