The effects of fenton type $(Fe^{+2}SO_4/H_2O_2)$ oxidation system on lipid and protein oxidation of grey mullet (Mugil cephalus)

Abstract

Oxidative damages of lipid and protein in grey mullet (Mugil cephalus) were investigated in vitroby using Fenton reactants $(Fe^{+2}SO_4/H_2O_2)$ to generate hydroxyl radical formation. Thiobarbutiricacid–reactive substances (TBARs, mg maonladehyde/ kg) were used to determine free radical-mediated oxidation of lipids. The oxidative modification of proteins was confirmed by carbonylformation using with 2,4-dinitrophenylhydrazine (DNPH) and DNPH labeled of oxidized proteinsby separated Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE). LipidsOxidation of grey mullet with $(Fe^{+2}SO_4/H_2O_2)$ gave a noticeable increase in TBARs value during 5hincubation. Protein carbonyl content decreased during the first 3h of incubation time on treatmentwith free radical generating system and then increased until 5th hours. At 3rd hours of incubation theintensity of the bands near 100 kDa and 150 kDa decreased and the bands above 50 kDadisappeared at 5th hours of incubation after exposure to $(Fe^{+2}SO_4/H_2O_2)$. These data suggest that freeradical generating system can alter the structure of a protein by leading to protein denaturation andincrease in lipid oxidation by leading to development of off- flavors and off-odors during storage,which cause quality loss and limited storage life.