IDENTIFICATION, CHARACTERIZATION AND QUANTIFICATION OF LIPID PEROXIDATION PRODUCTS IN RE-USED DEEP FRIED OIL FROM FOOD VENDORS IN SOUTHEASTERN NIGERIA

Daily consumption of highly oxidized products of fatty acids from re-used deep fried vegetable oil via intake of deep-fried foods leads to gradual accumulation of end products of lipid peroxidation, which are capable of distorting most biochemical homeostasis, with health complications such as inflammation of the vascular system. This research work aims to identify, characterize and quantify the presence of cytotoxic lipid peroxidation products in re-used deep fried culinary oil collected from different fast-food vendors within (Enugu, Ebonyi, Anambra, Abia and Imo) States in Eastern Nigeria. Hundred milliliters (100 mL) of re-used deep fried vegetable oil collected from different fast-food vendors within these States, were subjected to characterization, and further identification and quantification of end products of lipid peroxidation level using thiobarbituric acid reactive substances (TBARS) method, slightly modified ferrous oxidation-xylenol orange assay method (FOX2 assay) and GC-MS analysis. Our findings indicate significant (p<0.05) increase in aldehyde groups, lipid hydroperoxide concentrations, saponification values, rancidity, percentage free fatty acid values, acid values, and remarkable decrease in iodine values in comparison with fresh refined vegetable oil. Our result from Gas chromatography-mass spectrometry analysis of methylated re-used deep fried vegetable oil detected, Cholest-5-en-3-ol (3β)- a known inducer of echinocytic transformation of human erythrocytes and further causes decrease in osmotic fragility of red blood cells. The failure of methylation process to capture very short chain hydrocarbons necessitated the use of derivitazation method, which was able to detect already established cytotoxic product namely; trans, trans-2,4-decadienal, a highly reactive and pro-apoptotic α, β-unsaturated aldehyde capable of initiating nitrative/oxidative stress.