Drying procedure
Leek slices were dried on basket in a cabinet dryer (APV
& Pasilac, England). The cabinet dryer was equipped with an
electrical heater, adjustable centrifugal fan, drying basket and
proportional temperature controller. The air velocity in dryer
was measured with Testo 440 vane probe anemometer (Lutron,
Taiwan) with a precision of ±0.03 m/s.
The experimental data for drying of leek slices were obtained
at 50 ◦C temperature. The temperature in the dryer was regulated
to ±1 ◦C using a temperature controller. The air velocity above
the product was 2.5 m/s, and air was forced by a centrifugal fan.
The flow of the air was parallel to the product. Relative humidity
(RH) inside the drier was calculated by measuring the dry and
wet bulb temperatures and was 25% in the air temperature of
50 ◦C.
The dryer was started about 1 h before drying experiments
to achieve steady-state conditions. The samples (about 150 g)
were distributed uniformly within the drying basket. The weight
of samples in basket was recorded every 15 min by using a
digital balance (Mettler, model BB3000). The drying process
was conducted until a moisture content of 10 ± 0.5% (w.b.)
was reached. The product was cooled and then packed in low
density polyethylene (LDPE) bags that were heat-sealed. The
experiments were replicated three times and the average of the
moisture ratio at each value was used for drawing the drying
curves