Deep frying were carried out in a stainless steel electrical
open fryer (Takada, model ISB-306,) with a 3 L maximum
capacity pot of oil equipped with a stainless steel basket
and portable fiter system. There were 3 types of frying
systems used: VCO without antioxidant as control system,
VCO with 200 ppm of BHT and VCO with 200 ppm of
Zea mays extract. The frying for all systems was done
simultaneously. Approximately 120 g oil samples were
collected from each fryer to represent the sample for day 0
before frying. The remaining oil was heated at 180±5oC and
was allowed to equilibrate at this temperature for 30 min.
Fifteen batches of 100 g of French fries were fried for 3 min
for each batch at 20 min intervals daily. The fryers were left
uncovered during the frying experiment. The fryers were
turned off at the end of the frying experiment each day and
the oil was cooled to 60°C before being collected. Frying
oil (120 g) from each fryer was sampled into amber bottles
at the end of each day. All oil samples were flshed with
slow bubbles of nitrogen gas and stored at -20°C prior to
chemical analysis. The lids of the fryers were put on and
fryers were left overnight for the following’s day of frying.
The fryers were topped up to initial level to replenish the
used oil before the frying process of the next day. The
whole procedure for each oil blend system was repeated
consecutively for three days.