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

Abstract

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 T 2 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.