Frying process
Potato stripes (7.0 × 0.5 × 0.3 cm) were prepared and immersed in water
until use. Twenty-gram batches of potato stripes were fried in 2 l of
oil. Frying temperature was fixed at 180 °C using a bench-top deep-fryer
(Tefal model 1250, France) and a digital thermometer. Each batch was
fried for 5 min, followed by standing the oil for 15 min. This was
repeated for 8 h per day during four consecutive days. At the end of
each 4 h, about 20 g of the frying oil was filtered into a screw-cap
vial and promptly stored in the dark at –18 °C until use. The oil was
not replenished during the frying process. The process were conducted in
duplicate (Farhoosh and Moosavi, 2010).