Composition and authentication of virgin olive oil from French PDO regions by chemometric treatment of Raman spectra

Abstract

International audienceThe search for the origin and the authentication of virgin olive oils (VOOs) is a problem of topical interest. VOOs with the protected designation of origin (PDO) label can be subject to fraudulent practices owing to high price commanded by these oils. This work evaluates the capability of confocal Raman spectroscopy combined with chemometric treatments for determining the fatty acid and triacylglycerol (TAG) compositions of VOOs and for authenticating the PDO labels of six French VOOs. Fatty acid and TAG compositions were determined by chemometric analysis of the Raman spectra using the partial least square (PLS) algorithms. Predictions have provided good results on the high percentage compounds, but for the fatty acids at very low percentages the predicted results were very poor. The PLS-discriminant analysis model on Raman spectra was able to correctly classify 92.3% of French PDOs and 100% of PDO samples made with only one principal cultivar. However, it was noticeable that the first regression coefficient (which explains the greatest amount of variation of the data) obtained for each PDO could be compared one by one with the first regression coefficient obtained for the quantitative analysis of fatty acids and TAGs. The first regression coefficients obtained for PDOs differed widely from each other. Their study allowed interpreting the PDOs according to their chemical composition. This work confirms that fatty acid and TAG percentages may be used to authenticate French VOOs into PDO

A review of analytical methods measuring lipid oxidation status in foods: a challenging task

“…Two instrumental methods can be employed with Raman spectroscopy: confocal Raman spectroscopy with a powerful laser in visible range and Fourier Transform Raman spectroscopy. Most of the applications on oils have been performed by the later [129]. However, a portable Raman spectrometer has been recently developed [130], which, on the other hand, shows lower resolution than classic ones.…”

Discrimination of Olive Oil by Cultivar, Geographical Origin and Quality Using Potentiometric Electronic Tongue Fingerprints

“…From these, 34 samples were Chemlali olive oil, the predominant autochthonous olive variety, produced in Kairouan (16), Sfax (14) and Sidi Bouzid (four samples) regions. The other 26 samples of Sahli olive oil were produced in Kairouan (four), Mahdia (ten) and Sousse (12) regions. Samples were kept in the original dark amber bottles protected from the direct light exposition, during transport and storage.…”

“…For the potentiometric assays, a commercial reference Ag/AgCl electrode was used (Metrohm Ag/ AgCl double junction with SGG sleeve). Each sensor was identified a letter S (for sensor) followed by the number of the array (1 or 2) and the number of the membrane (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20).…”

Tracing molecular dephasing in biological tissue

“…Oils and lipids in fats have similar molecular composition and thus should have similar Raman active vibrational spectra. Raman active lines corresponding to C-C stretching vibration at ~1070 cm -1 and scissoring (C-H) modes at 1267 cm -1 [17] were targeted. The corresponding results are shown in Fig.…”