Metabolomic approach for quality classification of olive oils by gas chromatography coupled to quadrupole time-of-flight mass spectrometry and development of an alternaitve method

Abstract

Determining the quality of olive oil has always been a conflict, as to date, the only way that was available for classification was through tasting by a panel of experts. This differentiation, performed by a quite subjective method, could be complex, and sometimes leads to large discrepancies in the organoleptic qualities of the same oil depending on the taster to try it. Such discrepancies may result in misclassification of the oil, resulting in economic harm to producers, to determine a quality below the real to a particular product. The progress each day over chromatographic techniques coupled to mass spectrometry allows to reach detect differences in concentrations of trace compounds even in the range of parts per trillion. Through these techniques it can be quantified with high accuracy at these levels, something impossible for a tasting panel or other physicochemical techniques. In the same way, in highlighting differences between large groups of samples, technical progress with high resolving power, and the development of new information technologies has facilitated the emergence of complex statistical analyzes that allow, based a previous model, a sample assignment within a given group with a minimum data treatment. In this field, metabolomics is the most efficient methodology, as it allows, through statistical analysis of individual samples, create patterns of behavior of different groups and thus classify blind samples in each group with minimal error. In this work, a metabolomics approach has been carried out in order to create a statistical model to perform a classification between different quality olive oils. Hybrid quadrupole timeof- flight mass spectrometer (QTOF MS) coupled to gas chromatography (GC) has been used for untargeted metabolite fingerprinting. Differentiation from Extra Virgin olive oil, Virgin olive oil and Lampante olive oil has been carried out using XCMS application and multivariate analysis to GC-(Q)TOF MS data acquired. Finally an alternative technique, more selective and economical also based on purge and trap, but taking profit of the benefits of the direct thermal desorption in the injection system of a GC, coupled to a single quadrupole (MS) has been developed.