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

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Lipid oxidation during olive oil storage induces changes in the metabolite content of the oil, which can be measured using so-called quality indices. High values indicate poor quality oils that should be labeled accordingly or removed from the market. Based on quality indices measured over two years for two olive oils, the AComDim method was used to highlight the influence of five factors (olive oil type, oxygen, light, temperature and storage time) on oxidative stability during storage. To identify the significant factors, two full factorial experimental designs were built, each containing four of the five factors examined. The results showed that all five factors, as well as some two-factor interactions, were significant. Phenols and hydroperoxides were identified as being the most sensitive to these factors, and potential markers for the ageing of olive oil.

International audienceLeaching MIR spectroscopy Ion exchange resin γ-Irradiations of ion exchange resins were carried out under various experimental conditions, selected using an experimental design, to simulate the ageing of such nuclear wastes. Those resins are a commercial mixed bed, constituted of 75 wt.% of a cationic resin and 25 wt.% of an anionic resin, and both are pure cationic and anionic resins. Then, irradiated samples were leached, at two different temperatures (20 °C and 50 °C). Solid matrices were characterized by a spectroscopic technique and spectral data were analysed by the ANOVA Common Dimensions (AComDim) method to detect and highlight influential factors and interactions. Four factors were studied (absorbed dose under irradiation, atmosphere during irradiation, dose rate, leaching temperature and resin type) with several levels for each. In a first study of the separate resins, the absorbed dose and the irradiation atmosphere appeared as the most influencing factors for the anionic resin. The leaching temperature was significant but only in interaction with other factors, while this parameter was significant for the cationic and mixed bed resins. In a global study of all the spectral data, the resin type appeared as the most influential factor for the radiolysis of resins