Consequence of Commercial Fish Frying on Some Quality Parameters of Oil with Special Reference to Trans Fat

Abstract

In the present study, the quality of frying oil, as affected by commercial pan fish frying, was investigated. The quality of fresh frying oil, null replenishment (NR) oil, and discarded frying oil were evaluated by drawing out the oil samples from the fryer at the initial stage, just before the addition of new frying oil for level make-up and used oil of the last frying cycle, respectively. The parameters used to assess the quality were the fatty acid composition including trans fatty acid (TFA), free fatty acid, and peroxide values of frying oil. Gas chromatography-mass spectroscopy (GC-MS) was used to examine fatty acids profiles of the frying oils. Trans fatty acid in fresh oils varied from 2.5%–3.8% (except oil-6, which contained 13%), whereas NR oils and discarded oils contained 5.6%–14.8% and 7.3%–20.8% trans fatty acids, correspondingly. Free fatty acid in fresh, NR, and discarded oils were 0.12%–0.24%, 0.22%–1.74%, and 0.80%–3.39%, respectively. Peroxide value in fresh, NR, and discarded oils were determined to be 1.15–3.93, 2.71–7.51, and 2.84–14.68 meq of O2 /kg oil. It was observed that commercial fryers were not using the proper oil for frying. Furthermore, the last frying cycle just before discarding the oil may be dangerous for the health of consumers due to their significant level of TFA, free fatty acid, and peroxide values.