Évaluation de la qualité de l'huile de pulpe d'olive vierge de la variété Picholine marocaine

This work examines the effect of olives pitting on virgin olive oil quality. It compares physicochemical and gustative quality of oils obtained from whole olives and pitted ones. Oil analyses concerned free acidity, peroxide index, UV extinctions at 232 and 270 nm, total phenolics content and fatty acid composition. Degustation, by a panel composed of 54 students, used triangular discrimina-tive test to distinguish between whole and pitted olive oils taste; also, panel was invited to give personal preference for one of the two types of olive oils. Physicochemical data demonstrated that all oil samples are classed as extra virgin olive oil category. Data comparison of paired samples noticed no significant difference between pulp olive oil and whole olive oil. Pitting olives caused low but non-significant increase (P = 0,097) of total phenolics content and had no effect on fatty acid composition. Significant taste difference was noticed between whole olive oil and pulp olive oil (P = 0,029 < 0,05) and 39 % of panel members exhibited taste preference towards olive pulp oil. Keywords: Olive pulp oil, physicochemical characterization, chemical quality, gustative quality, triangular test, taste preference.Ce travail étudie l’effet du dénoyautage des olives sur la qualité de l’huile d’olive à travers une comparaison de la qualité physi-co-chimique et gustative de l’huile d’olive sans noyau (huile de pulpe d’olive) et celle avec noyau (habituellement préparée). Les paramètres mesurés sont: l’acidité libre, l’indice de peroxyde, l’absorption UV (K232 à 232 nm, K270 et ?K à 270 nm), la teneur en polyphénols totaux et la composition en acides gras. La dégustation, par un panel de 54 étudiants, a été réalisée d’une part selon le test discriminatif triangulaire, et d’autre part, en demandant aux sujets leur préférence de goût pour l’un des deux types d’huiles. L’analyse physico-chimique a permis de classer tous les échantillons dans la catégorie d’huiles d’olive vierges extra. La comparaison des données d’observations en paires relatives à l’acidité libre, à l’indice de peroxyde et aux extinctions spécifiques n’a pas décelé de différence significative entre les deux types d’huiles d’olive (avec ou sans noyau). Le dénoyautage a entraîné une légère hausse, bien que peu significative (P = 0,097) de la teneur en composés phénoliques, mais n’a pas eu d’effet significatif sur la composition en acides gras. La dégustation selon l’épreuve triangulaire a permis de révéler une différence de goût assez significative (P = 0,029 < 0,05). Par ailleurs, 39 % des dégustateurs ont manifesté une préférence de goût en faveur de l’huile de pulpe d’olive.Mots clés: Huile de pulpe d’olive, caractérisation physico-chimique, qualité chimique, qualité gustative, test triangulaire, préférence de goût

Effects of physical forcing on COastal ZOoplankton community structure: study of the unusual case of a MEDiterranean ecosystem under strong tidal influence (Project COZOMED-MERMEX).

International audienceThe COZOMED-MERMEX project aims at understanding how hydrodynamic forcing (currents, tides, winds)combine with anthropogenic forcing and climate to affect the variability of coastal Mediterranean zooplanktoncommunities under contrasting tidal influence. This study includes (i) a zero state of knowledge via a literaturereview of existing data and (ii) a case study on the system Boughrara lagoon - Gulf of Gabes. This ecosystemgives major services for Tunisia (about 65% of national fish production) but is weakened by its situation in aheavily anthropized area and under influence of urban, industrial and agricultural inputs. Besides this regionis subject to specific climate forcing (Sahelian winds, scorching heat, intense evaporation, flooding) whichpossible changes will be considered. The expected issues are (i) to improve our knowledge of hydrodynamicforcing on zooplankton and ultimately on the functioning of coastal Mediterranean ecosystems impacted byanthropogenic and climatic effects and (ii) to elaborate management tools to help preserving good ecologicalstatus of these ecosystems: hydrodynamic circulation model, mapping of isochrones of residence times, mappingof the areas of highest zooplankton abundances (swarms), and sensitive areas, etc. This project strengthensexisting scientific collaborations within the MERMEX program (The MerMex Group, 2011) and in the frameof an international joint laboratory (COSYS-Med) created in 2014. A first field mulidisciplinary campaign wasperformed in October 2016. The strategy combined measurements of sea level and currents (mooring of ADCP,Argonaute and tidal gauges), hydrological description of water masses (horizontal and vertical transect with aMinibat equipped with CTD, fluorescence and turbidity sensors) and discrete sampling of nutrients, DOC, POC,pico, nano, microphytoplankton and mesozooplankton. The first results allow a description of water currents andshows a good coupling between tidal cycles (ebb-flood and spring tide neap tide) and the dynamics of planktoniccompartments in the lagoon