Effects of repeated deep frying on refractive index and peroxide value of selected vegetable oils
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Date
2018-04
Journal Title
Journal ISSN
Volume Title
Publisher
IJAR
Abstract
The peroxide values and refractive indices of palm olein, sesame oil and sunflower oil were
evaluated before deep frying. The vegetable oils were used to frying white Irish potato chips
in three batches, with the peroxide value and the refractive indices of the oils determined after
every stage of deep frying. Results of the study show that both refractive index and peroxide
value of the vegetable oils largely vary with deep frying. The findings show that refractive
index and peroxide value of sesame palm and sunflower do increase on frying, though not in
a linear fashion. The refractive index of palm oil increased from 1.4653 to 1.4655 after frying
the three consecutive batches; the RI of sunflower oil increased from 1.4722 to 1.4724
respectively. There was no significant change in the refractive index of sesame oil. The
peroxide values of palm oil increased from 1.9948mEq/kg to 9.3020mEq/kg after three
consecutive deep frying. The value of peroxide of sunflower oil raised from 10.6359 mEq/kg
to 19.3101 mEq/kg while that of sesame increased from the initial 3.9914 mEq/kg to 11.9555
mEq/kg on frying the second batch and finally reduced to 11.3095 mEq/kg after frying the
third batch of Irish potato chips. Tables 3 and 4 show the relationship between refractive
index and peroxide value of the vegetable oil. These findings indicate that repeated deep
frying leads to corresponding rancidity and spontaneous deterioration of the vegetable oil.
Description
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Keywords
refractive index, peroxide value, vegetable oil, palm olein,, sesame oil,, sunflower oil