Nathalie Estephan

Dr. Nathalie Estephan

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Research Focus & Metrics

Academic Career Length

23Years (2004-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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15 May 2015 in Critical Reviews in Food Science and Nutrition
Verified
Journal Article
Closed access
SASamar Azzi
Samar Azzi
NENathalie Estephan
Nathalie Estephan
NONaïm Ouaini
Naïm Ouaini
DRDouglas N. Rutledge
Douglas N. Rutledge
The most commonly used technique to prepare samples for the analysis of wine volatile is the headspace solid-phase microextraction (HS-SPME). This method has gained popularity in last few years, as it is a unique solventless preparation technique. In this paper, a summary of recently published studies using HS-SPME for the analysis of wine aromas, with special emphasis on the method developed, has been compiled. Several papers are discussed in detail, mainly with respect to the SPME conditions used. A brief summary of the reviews related to HS-SPME analysis is given and discussed. Several parameters affecting the HS-SPME, such as the salt concentration and the agitation conditions, are used in the same way as used in several papers. The HS-SPME extraction proved to be sufficiently sensitive to satisfy legislative requirements related to low detection and quantification limits as well as method accuracy and precision requirements. However, in order to achieve the best performance and precision, the protocol needs to be optimized for each case. The effect of different parameters must be well characterized to ensure correct extraction and desorption to ensure the transfer of extracted compounds into the analytical system. The operating parameters, such as time, temperature, and agitation, must then be kept constant for all the samples.

11 March 2021 in Journal of Food Processing and Preservation
Verified
Journal Article
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WSW. Skaff
W. Skaff
RHR. El Hajj
R. El Hajj
LHLara Hanna-Wakim
Lara Hanna-Wakim
NENathalie Estephan
Nathalie Estephan

18 July 2023 in Plants
Verified
Journal Article
Open access
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MRMilad El Riachy
Milad El Riachy
PMPeter Joseph Moubarak
Peter Joseph Moubarak
GHGhenwa Al Hawi
Ghenwa Al Hawi
MGMyriam Geha
Myriam Geha
WMWalid Mushantaf
Walid Mushantaf
WSWadih Skaff
Wadih Skaff
In Lebanon, olive oil is an integral part of its history and culinary traditions. However, the quality of this product, originating from different growing regions of the country, is rarely addressed. The objectives of this study were to compare the fatty acids and phenolic profiles of virgin olive oils produced from two local and eight European varieties, and to use these profiles as a tool for their characterization. Seventy-six samples were collected from two olive-growing regions of Lebanon and at two harvesting times. Fatty acid composition was determined by gas chromatography with a flame ionization detector, total phenols was determined by spectrophotometry and individual phenols by high performance liquid chromatography with diode array detector. All samples were also analyzed using near infrared spectroscopy. The experimental data were collected in numerical matrices and treated by chemometric methods. The results showed the significant effect of the geographical origin, the olive variety and the harvesting time on the ripening and industrial yield of the olives and on the major fatty acids and phenols of olive oil. Moreover, the used chemometric methods allowed the discrimination of European olive varieties based on their high contents of oleic acid, oleacein and oleocanthal.

31 October 2021 in Journal of Fungi
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Journal Article
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CKCharbel Al Khoury
Charbel Al Khoury
Georges NemerGeorges Nemer
Georges Nemer
RHRichard A. Humber
Richard A. Humber
NENehme El-Hachem
Nehme El-Hachem
Jacques GuillotJacques Guillot
Jacques Guillot
Nabil Michel NemerNabil Michel Nemer
Nabil Michel Nemer
The cedar forests of Lebanon have been threatened by the outbreak caused by climate change of a web-spinning sawfly, Cephalcia tannourinensis (Hymenoptera: Pamphiliidae), which negatively impacted the survival of one of the oldest tree species on earth. In this study, we investigated the occurrence of naturally soil-inhabiting entomopathogenic fungi for their role in containing the massive outbreak of this insect. We used a combination of fungal bioexploration methods, including insect bait and selective media. Morphological features and multilocus phylogeny—based on Sanger sequencing of the transcripts encoding the translation elongation factor 1-alpha (TEF-α), RNA polymerase II second largest subunit (RBP2), and the nuclear intergenic region (Bloc) were used for species identification. The occurrence rate of entomopathogenic fungi (EPF) varied with location, soil structure, forest structure, and isolation method. From 15 soil samples positive for fungal occurrence, a total of 249 isolates was obtained from all locations using different isolation methods. The phylogenetic analysis confirmed the existence of two novel indigenous species: Beauveria tannourinensis sp. nov. and Beauveria ehdenensis sp. nov. In conclusion, the present survey was successful (1) in optimizing the isolation methods for EPF, (2) investigating the natural occurrence of Beauveria spp. in outbreak areas of C. tannourinensis, and (3) in characterizing the presence of new Beauveria species in Lebanese cedar forest soil.

28 October 2021 in Journal of Apicultural Research
Verified
Journal Article
Closed access
RHRita El Hajj
Rita El Hajj
Nabil Michel NemerNabil Michel Nemer
Nabil Michel Nemer
WSWadih Skaff
Wadih Skaff
NENathalie Estephan
Nathalie Estephan
Beekeeping and honey production have been of great historical, economic, and health interest in Lebanon. However, the Lebanese beekeeping sector is poorly documented, not to mention the challenging natural and economical threats the beekeepers face which result in a decrease in honey production. In order to inform needed outreach and education activities in Lebanon, a comprehensive survey was conducted among beekeepers covering all the Lebanese territory. This survey allowed the collection of valuable information from each beekeeper about the hives’ location and number as well as the harvest season and the beekeeping practices. Principal Component Analysis (PCA), a novel approach to analyzing survey data was used as it proved to be an efficient and rapid tool. PCA showed a significant difference among beekeepers regarding 1- their acquired knowledge in beekeeping, 2- their membership in a cooperative, 3- the number of hives they own, and 4- the honey storage conditions they use. In addition, the application of PCA attributed the difference in beekeeping practices between Lebanese beekeepers to the different geographical agricultural zones in the country. Finally, the results showed that beekeepers coming from the Baalbeck-Hermel zone lacked proper beekeeping training and management and that most of the surveyed-Lebanese beekeepers (87%) practiced migratory beekeeping all year long in relation to flowering plants. Our findings demonstrated that PCA was able to extract useful information from survey data and this study is the first document about the beekeeper situation in Lebanon, representing a cornerstone for improvement of this sector across the country.

6 February 2024 in Journal of Spectroscopy
Verified
Journal Article
Open access
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RHRita El Hajj
Rita El Hajj
WSWadih Skaff
Wadih Skaff
NENathalie Estephan
Nathalie Estephan
Honey is considered as a premium food produced by honeybees. It is highly appreciated by consumers around the world and raises a major concern nowadays which is ensuring its authenticity in respect to its production and its botanical origin. In Lebanon, honey is mainly multifloral which makes its authentication rather difficult. While mid-infrared (MIR) spectroscopy combined with multivariate analysis has proven to be successful in authenticating unifloral honey, the challenge with Lebanese honey lies in assessing its performance with multifloral honey. Therefore, this work aims to test the performance of common components analysis (CCA) applied on mid-infrared spectra in the authentication of multifloral Lebanese honey. For this purpose, 96 multifloral Lebanese honey samples of different floral sources were collected from different regions of the Lebanese territory and analyzed using MIR spectroscopy. CCA applied to the spectral data, allowed a separation between honeydew honey samples and floral honey samples. In addition, honey samples collected from the Bekaa plain region were differentiated from the other honey samples collected from all the other Lebanese geographical regions. This discrimination between the groups of honey samples is based essentially on their sugar composition.