Rapid detection of olive-pomace oil adulteration in extra virgin olive oils from the protected denomination of origin “Siurana” using excitation-emission fluorescence spectroscopy and three-way methods of analysis

Extra virgin olive oil (EVOO) is the highest-quality type of olive oil. This makes it also the most expensive. For this reason, it is sometimes adulterated with cheaper oils. One of these is olive-pomace oil (OPO). The protected denomination of origin (PDO) “Siurana” distinction is given to the EVOO produced in a specific area of the south of Catalonia. Here we study the potential of excitation-emission fluorescence spectroscopy (EEFS) and three-way methods of analysis to detect OPO adulteration in PDO “Siurana” olive oils at low levels (5%). First, we apply unfold principal component analysis (unfold-PCA) and parallel factor analysis (PARAFAC) for exploratory analysis. Then, we use the Hotelling T2 and Q statistics as a fast screening method for detecting adulteration. We show that discrimination between non-adulterated and adulterated samples can be improved using Fisher's linear discriminant analysis (LDA) and discriminant multi-way partial least squares (N-PLS) regression, the latter giving a 100% of correct classification. Finally, we quantify the level of adulteration using N-PLS.