Direct Determination of Antioxidants in Whole Olive Oil Using the SIFT‐MS‐TOSC Assay

Abstract

Abstract A modified Selected Ion Flow Tube Mass Spectrometry Total Oxyradical Scavenging (SIFT‐MS‐TOSC) assay has been used to assess the antioxidants present in olive oil samples. The assay compares antioxidants in emulsified olive oil competing with added 2‐keto‐4‐methylthiobutanoic acid (KMBA) for peroxyl radicals formed from thermal decomposition of 2,2′‐azobis (2‐amidinopropane) hydrochloride. No solvent extraction from the oil is required. The assay reaction is monitored by analysis of ethene, a break down product of KMBA, from attack by peroxyl radicals. A new simpler modification to the TOSC assay was found to produce reliable results requiring measurements of just a single concentration of emulsion. The results of the SIFT‐MS‐TOSC assay show correlation with results from the Folin Ciocalteu assay of total phenol content and HPLC analysis of several standard antioxidants. The use of hydroxyl radicals generated by the Fenton reaction of Fe 3+ with ascorbic acid was also investigated, but with less repeatable results. A wide range of antioxidant levels differing by more than a factor of 10 were found in 20 different olive oils examined.