Deep-Fat Frying of Potatoes in Palm Oil in Relation to Quality Characteristics Assessment

Sensory and chemical attributes of palm oil used for repeated and discontinuous deep-fat frying of
potato chips at elevated temperatures were followed. Polyunsaturated fatty acids (PUFAs) decreased in
direct proportion to frying times, whereas saturated FAs were found to inversely increase. A strong degree
of correlation (R2) was found between C18:2/C16:0 ratio and the frying time. Free fatty acids were released
and their concentration in the palm oil often increased with repeated use. From acid values and polar
compounds contents of the used palm oil, it was obvious that thermoxidative alterations took place
mainly instead of the hydrolytic process. Frying palm oil was also analyzed for ultraviolet absorption
(A232 and A268), peroxide value (PV) and thiobarbituric acid (TBA) value during repeated and discontinuous
deep-fat frying. The correlation coefficients (r) between heating times and A232, A268, PV and TBA
values were 0.82 , 0.45 , 0.42 and 0.95 , respectively . During frying stages, both A400 and A450 of the used
palm oil were measured. Frying times were highly correlated with the steady and proportional increment
in A400 and A450. Sensory analysis of the palm oil used in potatoes frying exhibited that quality deterioration
has taken place with the progression of frying times. During frying process, there was an inverse relationship
between odour and colour sensory scores and frying times with a correlation coefficients of r =
–0.9204 and –0.9667, respectively. Various prediction models for assessing accurately frying times using
different dependant variables were established.