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    LC-DAD/ESI-MS/MS characterization of phenolic constituents in Tunisian extra-virgin olive oils: Effect of olive leaves addition on chemical composition
    (Elsevier Science Bv, 2017) Ammar, Sonda; Kelebek, Haşim; Zribi, Akram; Abichou, Mounir; Selli, Serkan; Bouaziz, Mohamed
    The aim of the present research is to evaluate the chemical characterization of main compounds from Tunisian monocultivar extra virgin olive oil (EVOO) ('Chemlali', 'Chetoui', 'Zalmati' and 'crossbreeding Chemlali by Zalmati') extracted after the addition of different amounts (0% and 3%) of olive leaves. As expected for extra virgin olive oil, the main sterols found in all analyzed samples were beta-sitosterol, Delta-5-avenasterol, campesterol and clerosterol. Stigmasterol, 24 -methylene-cholesterol, cholesterol, campestanol, sitostanol, Delta-7-stigmastenol, Delta-5,24-stigmastadienol, and Delta-7-avenasterol were also found in all samples, but in lower amounts. Most of these compounds were significantly affected by the cultivars but not to be affected by added leaves at 3% to olives prior to the extraction process. The obtained results revealed that 14 phenolic compounds belonging to different phenolic types were characterized and quantified by an effective HPLC-DAD-ESI-MS/MS method. In all the studied olive oil samples, dialdehydic form of elenolic acid linked to hydroxytyrosol (3,4-DHPEA-EDA), oleuropein aglycon (3,4-DHPEA-EA), and ligstroside aglycon (p-HPEA-EA) were the most abundant compounds. In addition, EVOO from 'Chetoui cultivar extracted with 3% of olive leaves presented the highest amount of individual phenolic compounds. (C) 2016 Elsevier Ltd. All rights reserved.
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    LC-MS phenolic profiling combined with multivariate analysis as an approach for the characterization of extra virgin olive oils of four rare Tunisian cultivars during ripening
    (Elsevier Sci Ltd, 2017) Ben Brahim, Samia; Kelebek, Haşim; Ammar, Sonda; Abichou, Mounir; Bouaziz, Mohamed
    In this work, the phenolic composition of four rare cultivars grown under the same agronomical and environmental conditions was studied. This is to test the effects of cultivars and ripening index essentially on phenolic composition in olive oils as well as tocopherols composition, organoleptic profiling and oxidative properties. Furthermore, some agronomical traits were determined in which a general increase in the size of the fruit and oil contents were recorded for all cultivars. The phenolic fractions were identified and quantified using liquid chromatography coupled to diode array detection and electrospray ionization tandem mass spectrometry (LC-DAD-ESI-MS/MS) in multiple reaction monitoring mode (MRM). A total of 13 phenolic compounds belonging to different chemical families were determined. Qualitative and quantitative differences in phenolic composition were observed among cultivars and also among sampling times. On the contrary to the agronomical traits, a general decrease (p < 0.05) of total phenolic compounds was observed during maturation. Likewise, a decrease in tocopherols concentrations and oxidative properties was observed. (C) 2017 Elsevier Ltd. All rights reserved.