Oxidation Processes in Sicilian Olive Oils Investigated by a Combination of Optical and EPR Spectroscopy

Abstract

We monitor β-carotene and chlorophyll in an auto-oxidation process. A protocol based on spectroscopic measurements is presented and can be used for the quality control process of commercial olive oil.

Thermal Oxidation Rate of Oleic Acid Increased Dramatically at 140 °C Studied using Electron Spin Resonance and GC–MS/MS

“…Detection of the formed spin adducts could be applied to distinguish the lipid‐derived free radicals formed during lipid thermal oxidation. Dimethyl pyridine N‐oxide (DMPO) and α‐phenyl‐N‐tert‐butylnitrone (PBN) are the two most widely used spin traps in biological (Ricca et al, ; Velasco et al, ) and food systems (Cui et al, ; Qian et al, ), both of which lead to the formation of nitroxides. PBN has good lipophilic characteristics and high reactivity, which could be used to detect oxidative stability of frying oils (Chen et al, ; Pingret et al, ; Thomsen et al, ).…”

EPR Methods Applied on Food Analysis

“…Monitoring the signal of the PBN spin adducts by EPR consists a promising method for the determination of the lipid oxidation lag phase but not suitable for the lag phase of hydroperoxides and thus oil shelf-life [60]. The formation of free radicals in edible oils is catalyzed by unsaturated lipids, and in this autoxidation mechanism, there is a direct involvement of β-carotene and chlorophyll [61]. The EPR spectra of the heated oils showed also the formation of α-tocopheryl radical, suggesting that the α-tocopheryl radical might be used as an alternative marker for studying the oxidation state of edible oils [61,62].…”

“…The formation of free radicals in edible oils is catalyzed by unsaturated lipids, and in this autoxidation mechanism, there is a direct involvement of β-carotene and chlorophyll [61]. The EPR spectra of the heated oils showed also the formation of α-tocopheryl radical, suggesting that the α-tocopheryl radical might be used as an alternative marker for studying the oxidation state of edible oils [61,62]. The EPR spectra of edible oils heated at 180 C in contact with metals suggested that iron and aluminum do not significantly affect the oils.…”

Evaluation of the Oxidation Degradation Process of Biodiesel via 1H NMR Spectroscopy

“…These natural antioxidants have the advantage of being inexpensive and non-toxic. 18 In the literature there are different papers reporting the antioxidant properties and efficiency of different plants as rosemary, [19][20][21] blackberry, 5,22 senna leaves, 23 hibiscus, 23,24 oregano, 25 basil, 25 curcumin, 26 β-carotene, [26][27][28] etc. 1 H NMR (proton nuclear magnetic resonance) spectroscopy has been used along with standard analysis to analyze oils and its compositions regarded to acylglycerols, fatty acid alkyl esters (FAAEs), its byproducts.…”