‘Specialty’ or ‘Gourmet’ oils: a multivariate statistical approach for the rapid identification of their botanical species

In the last decade, the increase of consumers’ preferences for the pleasant sensorial features of oils of different botanical origin has favored the diffusion of the so-called ‘specialty’ or ‘gourmet’ oils, namely cold-pressed industrial virgin oils obtained from seeds, fruits, and nuts1. Besides their flavor and aroma, the peculiar features of ‘gourmet’ oils lay in their alleged health promoting activities2, and in their low global production amounts, which result in their high costs. However, the recent market deregulation of virgin and/or cold pressed vegetable oils, and at the same time their high commercial value, asks for analytical methods which assess their authenticity. The aim of this study was evaluating the possibility to identify the botanical origin of the oil-based raw material by the routine analysis of their fatty acid composition coupled with chemometric methods and to explore also a new untargeted approach to their identification applying just their color analysis. A comprehensive data collection of authentic ‘gourmet’ oils, belonging to eight different botanical species (i.e., Almond, Apricot, Avocado, Hazelnut, Mosqueta rose, Rosehip, Sunflower, and Walnut) plus Olive oil as the gold standard of cold-pressed virgin oils, was performed. Their fatty acid composition has been re-elaborated in a statistical multivariate approach applying Principal Component Analysis (PCA) and classification methods. Moreover, a simple, rapid, and non-destructive spectrophotometric analysis has been considered to discriminate among different species. Particularly, the raw diffuse reflectance spectra recorded in the spectral range 380-780 nm by a UV-Vis spectrophotometer endowed with an integrating sphere was taken into account and elaborated by chemometrics. This information was compared with the results obtained by the most common approach based on the CIELab parameters and a fusion matrix of chromatographic and spectral data was also investigated. Both the fatty acid composition and the color (total spectrum and colorimetric parameters) of these vegetal oils have proven to be two promising markers of their botanical authenticity. [1] N. Cicero, A. Albergamo, A. Salvo, G.D. Bua, G. Bartolomeo, V. Mangano, A. Rotondo, V. Di Stefano, G. Di Bella, G. Dugo, Food Res. Int. 2018, 109, 517–525. [2] E.M. Hernandez, Functional Dietary Lipids—Food Formulation. 2016, 69–101.