A New Ultra Rapid Screening Method for Olive Oil Health Claim Evaluation Using Selective Pulse NMR Spectroscopy

Abstract

One of the most important constituents of olive oil is the secoiridoid polyphenolic derivatives which present an increasing potential for health protection. The European Union legislation based on the scientific opinion of EFSA has permitted specific health claims related to the levels of specific phenolic compounds found in olive oil (5 mg per 20 g dose or 250 mg/kg). The key compounds that are responsible for the recognized health claim “protection of blood lipids from oxidative stress” are hydroxytyrosol, tyrosol and their derivatives. For this reason the accurate measurement of the levels of those compounds in olive oil is very important. As the present time there is no officially adopted method for their measurement because of well-known technical difficulties. There are several works concerning the chromatographic analysis of those compounds (HPLC-UV or LCMS) but their accuracy is questionable because as we have recently described oleocanthal and oleacein react with methanol and water which are commonly and officially used for the extraction of polyphenols and as constituents of the mobile phase during their analysis, leading to the formation of several artifacts and making the analysis very difficult. To overcome these problems that make the chromatographic analysis complicated and questionable we recently developed a simple and rapid method using quantitative Nuclear Magnetic Resonance (qNMR) including a simple extraction step to increase the concentration of the analytes and reduce the bulk lipid matrix. In this chapter the authors describe their study wherein they utilized their developed qNMR method in combination with the previously reported qNMR method to 100 commercial olive oil samples. They then presented the varieties presenting the highest concentrations of the studied compounds and discussed the need for a new classification system for extra virgin olive oils (EVOOs) based on their health benefits, according to the concentration of each of the above-mentioned compounds that each contains.