Determination of olive oil quality by gas chromatography coupled to mass spectrometry and multivariate analysis

Abstract

The determination of quality in olive oil has always been a bit conflictive, as the only way to classify the different oils so far has been the classification of the samples according to the sensory sensations of a group of testers, who decide if an olive oil has to be tagged as extra virgin, virgin or lampante (not for commercial use). As one can assume, this methodology is quite subjective, as in some cases the opinion of the testers may vary in such a significant way that the same sample is classified at the same time as virgin and lampante, depending on its organoleptic characteristics. These discrepancies can lead to a misclassification of the sample; causing considerable economical loses to both the producers and the market. The exponential development of chromatographic techniques, especially the ones coupled to mass spectrometry, allows to distinguish between minimal concentration differences, within the range of a few parts per quadrillion (ppq). By the use of these techniques, one can quantify samples at really low levels, something impossible to achieve for a group of testers or for other techniques used until now (pH measurement, electronic nose…). In the same way, in order to point out differences between groups of samples, the advance of high resolution techniques, as GC-(QTOF)MS, as well as the development of new computer technologies, has enhanced the rise of complex statistical analysis which allow, in reference to a previous model, to demarcate a sample within a determined group with a minimal statistical treatment. In this ambit, metabolomics is the most efficient technique, as it allows, trough the statistical analysis of individual samples, to create behavior patterns of different groups, and classify blind samples in each group with a minimal error. The objective of this work is thus the development of a gas chromatography-mass spectrometry based technology which allows us to establish differences in virgin olive oil (extra, virgin or lampante) through the use of metabolomic techniques and which gives a more objective point of view to the classification method in use known as “PANEL TEST”.