Effect of water content on thermal oxidation of oleic acid investigated by combination of EPR spectroscopy and SPME-GC-MS/MS

Abstract

Promotion of water to the thermal oxidation of oleic acid was detected by the combination of EPR, SPME-GC-MS/MS and GC. Spin-trapping technique was used to identify and quantify the radical species formed during thermal oxidation of oleic acid by using DMPO as electron spin trap. The most abundant radical species were identified as DMPO-alkyl radical adducts. EPR intensity plateau of the samples with 5% water content was 140% higher than the samples without water. It implies oleic acid samples with high water content had high level of oxidation rates. The proportion of aldehydes of the samples with 2% water content was the maximum about 59.97%. Among the formed products, (E,E)-2,4-decadienal has genotoxic and cytotoxic effects, whose percentage was nearly twice comparing with that of 5-0% water content. This study demonstrated that higher water content in frying systems would contribute to seriously oxidation and degradation of oleic acids.

Keywords: 5,5-Dimethyl-1-pyrroline N-oxide (PubChem CID: 1774); Acetic acid (PubChem CID: 176); Benzene (PubChem CID: 241); Diethyl ether (PubChem CID: 3283); EPR; Ethanol (PubChem CID: 702); Frying; Isooctane (PubChem CID:182333); Oleic acid; Oleic acid (PubChem CID: 445639); Phenolphthalein (PubChem CID: 4764); SPME-GC-MS/MS, 2, 4- (E,E)-decadienal; Toluene (PubChem CID: 1140);; Water content; potassium hydeoxide (PubChem CID: 14797).