Repetitive Use of Vegetable Cooking Oil and Effects on Physico-Chemical Properties – Case of Frying with Redfish ( Lutjanus fulgens )

Abstract

We investigated the effect of repetitive use of vegetable cooking oil using redfish (Lutjanus fulgens) as the food item that was fried with frytol cooking oil for 5 days in 6 batches of frying/day. The study results showed free fatty acid values of 2.407±0.32% and acid values of 4.815±0.605 mg KOHg-1, which were significantly higher compared to the Codex Alimentarius Commission standards. Peroxide values of 14.70 to 25.250 ± 2.179 meq O2/kg deviated from the Codex standard value of 10 meq O2/kg. The mean specific gravity of the oil also decreased from 0.901 (pure oil) to 0.887. The results showed degradation in the physico-chemical properties of the vegetable cooking oil after repetitive frying. We conclude that repetitive use of vegetable oilsafter 1-2 times of batch frying up to 250kg/batch should be avoided since changes in physico-chemical properties of the oil affect oil quality for human consumption. Oils not suitable for human consumption would be suitable for alternate uses including biodiesel production.