Yazar "Bouaziz, Mohamed" seçeneğine göre listele

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    Antioxidant Capacity, Sugar Content, and Tandem HPLC-DAD-ESI/MS Profiling of Phenolic Compounds from Aronia melanocarpa Fruits and Leaves (Nero and Viking Cultivars)
    (Amer Chemical Soc, 2024) Sasmaz, Hatice Kubra; Kılıç-Buyukkurt, Ozlem; Selli, Serkan; Bouaziz, Mohamed; Kelebek, Haşim
    This study examined the phenolic profile, sugar composition, and antioxidant capacities of chokeberry fruits and leaves obtained from four different Turkiye provinces. A total of 21 phenolics including phenolic acid and its derivatives, flavanols, anthocyanins, and flavonols were determined in the fruits, while the leaves had 19 phenolics, including phenolic acid and its derivatives, flavanols, and flavonols. The total amount of phenolic compounds was the highest in both fruits and leaves in the samples from the Bursa province. Cis 5-O-p-coumaroylquinic acid and secoxyloganin were quantified for the first time in both fruits and leaves. In summary, it was found that different geographical locations significantly affected the phenolics, sugar contents, and antioxidant activities of the fruits and leaves.
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    Gas Chromatography-Mass Spectrometry-Olfactometry To Control the Aroma Fingerprint of Extra Virgin Olive Oil from Three Tunisian Cultivars at Three Harvest Times
    (Amer Chemical Soc, 2018) Ben Brahim, Samia; Amanpour, Asghar; Chtourou, Fatma; Kelebek, Haşim; Selli, Serkan; Bouaziz, Mohamed
    Gas chromatography-mass spectrometry-olfactometry was used for the analysis of volatile compounds and key odorants of three less studied Tunisian olive oil cultivars for the first time. A total of 42 aroma compounds were identified and quantified in extra virgin olive oils. The present study revealed that the most dominant volatiles in olive oil samples qualitatively and quantitatively were aldehydes and alcohols, followed by terpenes and esters. Indeed, chemometric analysis has shown a correlation between chemical compounds and sensory properties. The determination of aroma-active compounds of olive oil samples was carried out using aroma extract dilution analysis. A total of 15 aroma-active compounds were detected in the aromatic extract of extra virgin olive oil, of which 14 were identified. On the basis of the flavor dilution (FD) factor, the most potent aromatic active compound was hexanal (FD = 512) in Fakhari olive oil, (FD = 256) in Touffehi oils, and (FD = 128) in Jemri olive oil.
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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.
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    Safe and Fast Fingerprint Aroma Detection in Adulterated Extra Virgin Olive Oil Using Gas Chromatography-Olfactometry-Mass Spectrometry Combined with Chemometrics
    (Springer, 2021) Drira, Malika; Güçlü, Gamze; Portoles, Tania; Jabeur, Hazem; Kelebek, Haşim; Selli, Serkan; Bouaziz, Mohamed
    The undeclared blending of extra virgin olive oils (EVOOs) with refined pomace olive oils (RPOO) is a well-known fraudulent practice. Despite the efforts made, it still remains a highly challenging authenticity issue to deal with. The present paper presents a fast fingerprint aroma technique, namely gas chromatography-olfactometry-mass spectrometry, which were tested as rapid screening tools for the detection of this adulteration.To overcome the lack of real adulterated samples was used to prepare EVOO mixtures with RPOO at different percentages. Besides, the quality indices was used as good markers to detect the illicit blends from the authentic oils such as K-232 with 4% RPOO, K-270 with 3% RPOO, and the variation of specific extinction (Delta K) of the adulterated EVOO with 10% RPOO. The addition of > 20% RPOO to EVOO would not be detected by the amount of TC18:1, fatty acids, and peroxide value. Moreover, using the sum of octadecadienoic and octadecatrienoic TFA isomers (TC18:2 + TC18:3) was confirmed to be good purity indices for the adulteration with 10 and 20% of RPOO. However, the main triglyceride found in oils samples were SOL + POO, OOL + LnPP, and OOO + PoPP as expected from the high oleic acid and low contents in linoleic and linoleic acid. Regarding volatile composition, thirty-four relevant aroma compounds and twenty-one key odorants were quantified in EVOO, RPOO, and EVOO adulterated with 1-20% of RPOO.
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    Targeted analysis for detection the adulteration in extra virgin olive oil's using LC-DAD/ESI-MS/MS and combined with chemometrics tools
    (Springer, 2020) Drira, Malika; Kelebek, Haşim; Güçlü, Gamze; Jabeur, Hazem; Selli, Serkan; Bouaziz, Mohamed
    The hand-held LC-DAD/ESI-MS/MS approach was employed, for the first time, for the quantification of extra virgin olive oil (EVOO) adulteration with refined pomace olive oil (RPOO). The total polyphenols (TP) and sterols were quantified according to their chemical methods, with more reliable methods required in this field to avoid undue dependence on chlorophylls, carotenoids contents and antioxidant activity (DPPH assays), which were evaluated by spectrophotometric methods. Some differences concerning the antioxidant activity and the TP content were observed. Actually, Chemlali EVOO activity was the most pronounced (13.84 +/- 0.21%) and it contained the highest TP content (284.54 +/- 4.27 mg/kg). Indeed, a correlation between antioxidant activity, TP and oxidative stability was established herewith. The metabolomics data were elaborated with the help of chemometric tools i.e. principal component analysis (PCA) and hierarchical cluster analysis (HCA). This approach allowed the estimation of the best discrimination markers for EVOO authenticity evaluation (i.e. Hydroxytyrosol quinone, oxidized hydroxytyrosol, 3,4-DHPEA-EA, p-HPEA (tyrosol), p-coumaric acid, luteolin, decarboxymethyl 10-hydroxyoleuropein aglycon, beta-sitosterol apparently; campesterol, stigmasterol, increment Delta-7-stigmastenol and increment Delta-7-avenasterol). [GRAPHICS] .