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Dive into the research topics where Michele Lees is active.

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Featured researches published by Michele Lees.


Journal of Agricultural and Food Chemistry | 2008

Determination of origin of Atlantic salmon (Salmo salar): the use of multiprobe and multielement isotopic analyses in combination with fatty acid composition to assess wild or farmed origin.

Freddy Thomas; Eric Jamin; Karine Wietzerbin; Regis Guerin; Michele Lees; Eric Morvan; Isabelle Billault; Solène Derrien; Jose Manuel Moreno Rojas; Francesca Serra; Claude Guillou; Marit Aursand; Lesley McEvoy; Angelika Praël; Richard J. Robins

Variability within the stable isotope ratios in various lipidic fractions and the fatty acid composition of muscle oil has been analyzed for a large sample (171 fish) of wild and farmed Atlantic salmon ( Salmo salar) from 32 origins within Europe, North America, and Tasmania. Sampling was extended over all seasons in 2 consecutive years and included fish raised by different practices, in order to maximize the range of variation present. It is shown that two readily measured parameters, delta 15N measured on choline and delta18 O measured on total oil, can be successfully used to discriminate between fish of authentic wild and farmed origin. However, the certainty of identification of mislabeling in market-derived fish is strengthened by including the percentage of linoleic acid C18:2n-6 in the lipidic fraction. Thus, several apparent misidentifications were found. The combination of these three analytical parameters and the size of the database generated makes the method practical for implementation in official laboratories as a tool of labeling verification.


Food Chemistry | 2015

Fast and global authenticity screening of honey using 1H-NMR profiling

Marc Spiteri; Eric Jamin; Freddy Thomas; Agathe Rebours; Michele Lees; Karyne M. Rogers; Douglas N. Rutledge

An innovative analytical approach was developed to tackle the most common adulterations and quality deviations in honey. Using proton-NMR profiling coupled to suitable quantification procedures and statistical models, analytical criteria were defined to check the authenticity of both mono- and multi-floral honey. The reference data set used was a worldwide collection of more than 800 honeys, covering most of the economically significant botanical and geographical origins. Typical plant nectar markers can be used to check monofloral honey labeling. Spectral patterns and natural variability were established for multifloral honeys, and marker signals for sugar syrups were identified by statistical comparison with a commercial dataset of ca. 200 honeys. Although the results are qualitative, spiking experiments have confirmed the ability of the method to detect sugar addition down to 10% levels in favorable cases. Within the same NMR experiments, quantification of glucose, fructose, sucrose and 5-HMF (regulated parameters) was performed. Finally markers showing the onset of fermentation are described.


Phytochemistry | 2003

Quantitative 2H NMR analysis of deuterium distribution in petroselinic acid isolated from parsley seed.

Sébastien Guiet; Richard J. Robins; Michele Lees; Isabelle Billault

We have previously demonstrated that 2H distribution in fatty acids is non-statistical and can be related to isotopic discrimination during chain extension and desaturation. Petroselinic acid (C18:1 Delta(6)), a fatty acid characteristic of the seeds of the Apiaceae, has been shown to be biosynthesised from palmitoyl-ACP (C16:0) by two steps, catalysed by a dedicated Delta(4)-desaturase and an elongase. We have now demonstrated that the isotopic profile resulting from this pathway is similar to that of the classical plant fatty acid pathway but that the isotopic fingerprint from both the desaturase and elongase steps show important differences relative to oleic and linoleic acid biosynthesis.


Food Chemistry | 2017

Combination of 1H NMR and chemometrics to discriminate manuka honey from other floral honey types from Oceania

Marc Spiteri; Karyne M. Rogers; Eric Jamin; Freddy Thomas; Sophie Guyader; Michele Lees; Douglas N. Rutledge

Manuka honey is a product produced essentially in New Zealand, and has been widely recognised for its antibacterial properties and specific taste. In this study, 264 honeys from New Zealand and Australia were analysed using proton NMR spectroscopy coupled with chemometrics. Known manuka markers, methylglyoxal and dihydroxyacetone, have been characterised and quantified, together with a new NMR marker, identified as being leptosperin. Manuka honey profiling using 1H NMR is shown to be a possible alternative to chromatography with the added advantage that it can measure methylglyoxal (MGO), dihydroxyacetone (DHA) and leptosperin simultaneously. By combining the information from these three markers, we established a model to estimate the proportion of manuka in a given honey. Markers of other botanical origins were also identified, which makes 1H NMR a convenient and efficient tool, complementary to pollen analysis, to control the botanical origin of Oceania honeys.


Rapid Communications in Mass Spectrometry | 2009

Inter-laboratory comparison of elemental analysis and gas chromatography/combustion/isotope ratio mass spectrometry. II. δ15N measurements of selected compounds for the development of an isotopic Grob test

Giovanni Calderone; Francesca Serra; Michele Lees; Armin Mosandl; Fabiano Reniero; Claude Guillou; José Manuel Moreno-Rojas

An inter-laboratory exercise was carried out by a consortium of five European laboratories to establish a set of compounds, suitable for calibrating gas chromatography/combustion/isotope ratio mass spectrometry (GC-C-IRMS) devices, to be used as isotopic reference materials for hydrogen, carbon, nitrogen and oxygen stable isotope measurements. The set of compounds was chosen with the aim of developing a mixture of reference materials to be used in analytical protocols to check for food and beverage authentication. The exercise was organized in several steps to achieve the certification level: the first step consisted of the a priori selection of chemical compounds on the basis of the scientific literature and successive GC tests to set the analytical conditions for each single compound and the mixture. After elimination of the compounds that turned out to be unsuitable in a multi-compound mixture, some additional oxygen- and nitrogen-containing substances were added to complete the range of calibration isotopes. The results of delta(13)C determinations for the entire set of reference compounds have previously been published, while the deltaD and delta(18)O determinations were unsuccessful and after statistical analysis of the data the results did not reach the level required for certification. In the present paper we present the results of an inter-laboratory exercise to identify and test the set of nitrogen-containing compounds present in the mixture developed for use as reference materials for the validation of GC-C-IRMS analyses in individual laboratories.


Analytical and Bioanalytical Chemistry | 2008

Fruit juice authentication by 1H NMR spectroscopy in combination with different chemometrics tools

M. Cuny; E. Vigneau; G. Le Gall; Ian J. Colquhoun; Michele Lees; Douglas N. Rutledge


Food Authenticity and Traceability | 2003

6 – NMR spectroscopy in food authentication

G. le Gall; Ian J. Colquhoun; Michele Lees


Journal of Mass Spectrometry | 2007

Inter-laboratory comparison of elemental analysis and gas chromatography combustion isotope ratio mass spectrometry (GC-C-IRMS). Part I: δ13C measurements of selected compounds for the development of an isotopic Grob-test

Francesca Serra; A. Janeiro; G. Calderone; J. M. Moreno Rojas; C. Rhodes; L. A. Gonthier; F. Martin; Michele Lees; A. Mosandl; S. Sewenig; U. Hener; B. Henriques; L. Ramalho; Fabiano Reniero; A. J. Teixeira; Claude Guillou


Chemometrics and Intelligent Laboratory Systems | 2016

Common components and specific weights analysis: a tool for metabolomic data pre-processing

Elodie Dubin; Marc Spiteri; Anne-Sophie Dumas; Jérôme Ginet; Michele Lees; Douglas N. Rutledge


Analytical and Bioanalytical Chemistry | 2016

Data fusion between high resolution (1)H-NMR and mass spectrometry: a synergetic approach to honey botanical origin characterization.

Marc Spiteri; Elodie Dubin; Jérôme Cotton; Marion Poirel; Bruno Corman; Eric Jamin; Michele Lees; Douglas N. Rutledge

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