The frying was simultaneously conducted in three 8 L capacity
restaurant style stainless steel deep fryers (General Electric Company,
New York, USA). The oils (3.75 L) was heated at 185 ± 5 C
for 7 h daily for 14 days. A batch of 200 g of frozen French fries
was fried for 5 min for a total of eight batches per frying day. At
the end of each frying day, fryers were shut off and left to cool
overnight. Two 25 mL samples of oil from each of the fryers were
taken daily and kept frozen at 16 C until analysed. Before commencing
frying each day, oils were filtered to remove solid debris.
Oil was replenished every second day of frying with 500 mL of
fresh oil.