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Your search keyword '"Céline Poncet‐Legrand"' showing total 19 results
Start Over Author "Céline Poncet‐Legrand" Topic 0104 chemical sciences
19 results on '"Céline Poncet‐Legrand"'

1. Impact of the variety on the adsorption of anthocyanins and tannins on grape flesh cell walls

Author

Elissa Abi-Habib, Stéphanie Roi, Stéphanie Carrillo, Jeanett Hansen, Aude Vernhet, Bodil Jørgensen, Céline Poncet-Legrand, Thierry Doco, Sciences Pour l'Oenologie (SPO), Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), University of Copenhagen = Københavns Universitet (KU), Agropolis Fondation1603-001, and ANR-10-LABX-0001,AGRO,Agricultural Sciences for sustainable Development(2010)

Subjects
[SDV.SA]Life Sciences [q-bio]/Agricultural sciences, 0106 biological sciences, [SDV]Life Sciences [q-bio], NONCOVALENT INTERACTION, Wine, 01 natural sciences, Anthocyanins, chemistry.chemical_compound, Cell Wall, Tannin, Vitis, Food science, PART II, Winemaking, chemistry.chemical_classification, Nutrition and Dietetics, Pulp (paper), food and beverages, anthocyanins, WINE POLYPHENOLS, Composition (visual arts), adsorption isotherms, PROANTHOCYANIDINS, Biotechnology, EXTRACTION, pulp cell walls, comprehensive microarray polymer profiling, PROCYANIDINS, engineering.material, HIGH-THROUGHPUT, Adsorption, stomatognathic system, tannins, Ethanol, Flesh, fungi, 010401 analytical chemistry, interactions, 0104 chemical sciences, MODEL, POLYSACCHARIDE, chemistry, Fruit, Anthocyanin, engineering, [CHIM.OTHE]Chemical Sciences/Other, Tannins, Agronomy and Crop Science, SKIN, 010606 plant biology & botany, Food Science
Abstract

BACKGROUND During winemaking, after extraction from the skins, anthocyanins and tannins adsorb onto the pulp flesh cell walls. This study aims to quantify the amounts adsorbed and their impact on wine composition, the impact of variety and ethanol on adsorption, and whether the presence of anthocyanins plays a role and impacts tannin adsorption. RESULTS Anthocyanin and tannin fractions obtained by mimicking winemaking conditions were mixed with fresh flesh cell walls of two varieties: Carignan and Grenache. Adsorption isotherms were measured. Adsorption of tannins was higher with Carignan than with Grenache and decreased when the ethanol content increased. In comparison, anthocyanins were adsorbed in small amounts, and their mixing with tannins had no impact on their adsorption. The differences were related to differences in pulp cell wall composition, particularly in terms of extensins and arabinans. CONCLUSION Adsorption of tannins, which can reach 50% of the initial amount, depends on the pulp cell wall composition. This needs to be further investigated. This article is protected by copyright. All rights reserved.

Published
2021
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2. Multimethod Approach for Extensive Characterization of Gallnut Tannin Extracts

Author

Christine Le Guernevé, Frédéric Véran, Pascale Williams, François Garcia, Céline Poncet-Legrand, Hélène Hallé, Aude A. Watrelot, Véronique Cheynier, Bertrand Robillard, Emmanuelle Meudec, Sciences Pour l'Oenologie (SPO), Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut Oenologique de Champagne (IOC), European Union (EU), and Région Grand-Est

Subjects
Magnetic Resonance Spectroscopy, Antioxidant, 1H DOSY NMR, medicine.medical_treatment, 1H 2D 1H/13C, gel permeation chromatography, Mass spectrometry, 01 natural sciences, Gel permeation chromatography, Quercus, Tandem Mass Spectrometry, enological tannins, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, medicine, Nuts, Tannin, 31P NMR, [CHIM]Chemical Sciences, Chromatography, High Pressure Liquid, UPLC−DAD−ESI−MS, Wine, chemistry.chemical_classification, Chromatography, Plant Extracts, 010405 organic chemistry, Chemistry, polygalloylglucose, 010401 analytical chemistry, General Chemistry, molecular weight distribution, Hydrolyzable Tannins, antioxidant properties, 0104 chemical sciences, Heteronuclear molecule, Molar mass distribution, Composition (visual arts), General Agricultural and Biological Sciences, gallotannins
Abstract

International audience; Gallotannins extracted from gallnuts are commonly added to wine to improve its properties. They consist of mixtures of galloylester derivatives of glucose. However, their composition and properties are not well-established. In this study, methods based on liquid chromatography coupled to ultraviolet–visible detection and mass spectrometry, size-exclusion chromatography, and one-dimensional (31P) and two-dimensional (1H diffusion ordered spectroscopy, 31P total correlated spectroscopy, and 1H/13C heteronuclear single-quantum correlation and heteronuclear multiple-bond correlation) nuclear magnetic resonance spectroscopies have been implemented for extensive chemical characterization of three commercial gallnut tannin extracts. Differences in the proportions of the different constituents (gallic, digallic, and trigallic acids and galloylglucose derivatives) and in the structure and molecular weight distributions of gallotannins were demonstrated between the three extracts, with chains containing 8.5, 12.2, and 12.4 galloyl groups on average for TAN A, TAN B1, and TAN B2, respectively. The antioxidant capacities of the extracts, evaluated using the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) method, were similar and related mostly to their total tannin content, with only a limited impact of the tannin composition.

Published
2020
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3. Wine Thermosensitive Proteins Adsorb First and Better on Bentonite during Fining: Practical Implications and Proposition of Alternative Heat Tests

Author

Philippe Cottereau, Aude Vernhet, Frédéric Charrier, Céline Poncet-Legrand, Eric Meistermann, Patrick Chemardin, Sciences Pour l'Oenologie (SPO), Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Institut Français de la Vigne et du Vin (IFV), and French Ministry of Food and Agriculture [Compte d'Affectation Speciale Developpement Agricole et Rural (CasDAR)] 1402

Subjects
hard and soft proteins, Hot Temperature, Food Handling, [SDV]Life Sciences [q-bio], Wine, wine proteins, 01 natural sciences, Fluorescence spectroscopy, bentonite fining, 0404 agricultural biotechnology, Adsorption, Vitis, Practical implications, Plant Proteins, alternative heat tests, haze formation, Chemistry, 010401 analytical chemistry, food and beverages, 04 agricultural and veterinary sciences, General Chemistry, Hydrogen-Ion Concentration, 040401 food science, Accelerated aging, Lower temperature, 0104 chemical sciences, Chemical engineering, Bentonite, General Agricultural and Biological Sciences, [CHIM.OTHE]Chemical Sciences/Other
Abstract

International audience; Bentonite fining is the most popular treatment used to remove proteins in white and rose wines. The usual heat test used to adjust the bentonite dose consists of heating the wine during 30 min at 80 degrees C. At this temperature, all of the proteins are unfolded, and this can lead to an overestimation of the dose. We have shown that proteins adsorb on bentonite in a specific order and, more importantly, that the proteins responsible for haze formation adsorb first. Fluorescence spectroscopy showed that this is due to the structural properties of proteins, which can be classified as hard and soft proteins. Alternative heat tests were performed at a lower temperature (40 degrees C) and showed a better correlation with accelerated aging. These tests were also less dependent upon the wine pH.

Published
2020
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4. Colloidal Dispersions of Tannins in Water−Ethanol Solutions

Author

Aude Vernhet, Drazen Zanchi, Ralf Schweins, Bernard Cabane, Céline Poncet-Legrand, Damien Cartalade, Christophe Tribet, Laboratoire de Physique Théorique et Hautes Energies (LPTHE), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Laboratoire de Physico-Chimie des Polymères et des Milieux Dispersés (PPMD), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), and Institut LAUE LANGEVIN

Subjects
Population, Centrifugation, 01 natural sciences, Colloid, 0404 agricultural biotechnology, Adsorption, Electrochemistry, Tannin, General Materials Science, Colloids, [SDV.BBM.BC]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biochemistry [q-bio.BM], education, GRAPE SEED TANNINS, WINE, MODEL, CONSTITUENTS, AGGREGATION, Spectroscopy, chemistry.chemical_classification, education.field_of_study, Chromatography, Ethanol, Chemistry, 010401 analytical chemistry, Electrophoresis, Capillary, Water, 04 agricultural and veterinary sciences, Surfaces and Interfaces, Condensed Matter Physics, 040401 food science, Small-angle neutron scattering, 0104 chemical sciences, Solutions, Solvent, Chemical engineering, Ionic strength, Particle, Tannins
Abstract

Correspondance: drazen@lpthe.jussieu.fr aude.vernhet@supagro.inra.fr; International audience; The molecular interactions of grape-seed tannins dissolved in water-ethanol solutions have been studied through small angle neutron scattering, light scattering, and physical separation techniques. Through selective precipitation in different solvent mixtures, three populations of tannin macromolecules have been identified: T1 (2% of the total tannin), which forms colloidal particles when the ethanol content of the solvent is brought below phi(A) = 0.6; T2a (33% of the tannin), which phase-separates below phi(A) = 0.08 in ionic conditions that are typical of wine; and T2b (65% of the tannin), which remains in solution regardless of ethanol content. Each population remains molecularly dissolved (i.e., it does not form any association structures such as stacks or micelles) until the threshold where dense colloidal particles are formed through nucleation and growth. The colloidal dispersions are metastable, due to the adsorption of organic acids on the particle surfaces; increasing ionic strength and reducing ethanol content cause the loss of this metastability and the aggregation of the particles

Published
2007
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5. Isolation of Flavanol-Anthocyanin Adducts by Countercurrent Chromatography

Author

Céline Poncet-Legrand, Emmanuelle Meudec, Véronique Cheynier, Erika Salas, Nils Köhler, Peter Winterhalter, Hélène Fulcrand, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Department of Animal Sciences [Madison], University of Wisconsin-Madison, and Technical University Braunschweig

Subjects
Spectrometry, Mass, Electrospray Ionization, Flavonols, [SDV]Life Sciences [q-bio], Electrospray ionization, FRAGMENTATION PATTERN, Wine, Mass spectrometry, 01 natural sciences, Analytical Chemistry, Adduct, Anthocyanins, FLAVONOID, chemistry.chemical_compound, 0404 agricultural biotechnology, Countercurrent chromatography, Glucoside, [SDV.IDA]Life Sciences [q-bio]/Food engineering, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Countercurrent Distribution, Chromatography, High Pressure Liquid, PREPARATIVE CHROMATOGRAPHY, Chromatography, Chemistry, 010401 analytical chemistry, Aqueous two-phase system, 04 agricultural and veterinary sciences, General Medicine, 040401 food science, 0104 chemical sciences, Polyphenol, RED WINE, Anthocyanin
Abstract

International audience; Pigments of the flavanol-anthocyanin (F-A+) type detected earlier in wine are synthesized using a protocol adapted from the synthesis of procyanidin dimers. The F-A+ adduct thus obtained is purified by countercurrent liquid-liquid partition, currently referred to as countercurrent chromatography (CCC). The solvent system consists of tert-butyl methyl ether-n-butanol-acetonitrile-water (2:2:1:5, acidified with 0.1% trifluoroacetyl) with the light organic phase acting as a stationary phase and the aqueous phase as the mobile phase. Four fractions are recovered and analyzed by high-performance liquid chromatography coupled to a diode-array detector and electrospray ionization mass spectrometer. The multilayer CCC method allowed the separation of pigments in three different groups. The first group consists of hydrosoluble pigments present in fraction 1; the second group consists of the F-A+ adducts [catechin-malvidin 3 glucoside (Mv3glc), along with some (catechin)2-Mv3glc]; and the third group is their anthocyanin precursor, Mv3glc.

Published
2005
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6. Flavan-3-ol Aggregation in Model Ethanolic Solutions: Incidence of Polyphenol Structure, Concentration, Ethanol Content, and Ionic Strength

Author

and Véronique Cheynier, Aude Vernhet, Céline Poncet-Legrand, Damien Cartalade, Jean-Luc Putaux, Centre de Recherches sur les Macromolécules Végétales (CERMAV), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)

Subjects
chemistry.chemical_classification, Chemistry, 010401 analytical chemistry, food and beverages, 04 agricultural and veterinary sciences, Surfaces and Interfaces, Polymer, Degree of polymerization, Condensed Matter Physics, 040401 food science, 01 natural sciences, 0104 chemical sciences, Solvent, Colloid, 0404 agricultural biotechnology, Dynamic light scattering, Ionic strength, Polyphenol, Electrochemistry, Tannin, Organic chemistry, General Materials Science, [SDV.AEN]Life Sciences [q-bio]/Food and Nutrition, ComputingMilieux_MISCELLANEOUS, Spectroscopy
Abstract

International audience; Colloidal interactions involving polyphenols play a crucial part in wine stability, clarification, and taste. Though there is some evidence that polyphenolic compounds form stacks and aggregates in hydroalcoholic solutions, only little is known about their colloidal behavior. The aim of this study was, thus, to investigate in model ethanolic solutions the colloidal aggregation of flavan-3-ol monomers and polymer fractions extracted from grape seeds as well as apple and pear parenchyma. Aggregation was studied by means of phase diagrams, and aggregates were characterized by dynamic light scattering and cryo-transmission electron microscopy. Several parameters were studied: (i) the incidence of the tannin structure (mean degree of polymerization, mDP, and percentage of galloylation) and concentration (between 10(-2) and 5 g L-1) and (ii) the incidence of the ethanol content (from 2 to 20%) and ionic strength (from 10(-3) to 10(-1) M) of the solvent. Regarding the tannin structure, galloylation enhanced the formation of aggregates as far as monomers were concerned, but this could not be confirmed with polymers. The mDP had a complex effect: aggregation increased first with mDP for relatively low molecular weight polymers but decreased again for higher molecular weight fractions. This suggests that the higher molecular weight polymers can adopt a conformation in solution that enhances their solubility. Increasing the ionic strength resulted in a much lower tannin solubility and, when soluble, in the formation of bigger and much more polydisperse particles (salting-out effect). The ethanol content of the solvent also had a strong incidence on self-aggregation: increasing the ethanol content resulted in higher tannin solubilities and smaller and less polydisperse colloidal aggregates. This could be linked to the superficial tension properties of solvents containing various amounts of ethanol and confirmed the determinant part played by lyophobic interactions in flavan-3-ol aggregation.

Published
2003
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7. Grape seed and apple tannins : Emulsifying and antioxidant properties

Author

Céline Poncet-Legrand, Maria-Cruz Figueroa-Espinoza, Eric Dubreucq, Andrea Zafimahova, Pedro G. Maldonado Alvarado, Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Sciences Pour l'Oenologie (SPO), Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)

Subjects
Models, Molecular, Antioxidant, medicine.medical_treatment, Food chemistry, 01 natural sciences, Antioxidants, Analytical Chemistry, tannin, Castor wax, 0404 agricultural biotechnology, catechin, tannins, grappe de raisin, medicine, Tannin, Organic chemistry, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, Vitis, CAT assay, chemistry.chemical_classification, emulsion, tanin, Plant Extracts, Chemistry, 010401 analytical chemistry, Polyphenols, crab apples, 04 agricultural and veterinary sciences, General Medicine, 040401 food science, 0104 chemical sciences, poly(vinyl alcohol), pomme, Proanthocyanidin, Polyphenol, Emulsifying Agents, Malus, Castor oil, Seeds, Emulsion, Emulsions, Oxidation-Reduction, Food Science, medicine.drug
Abstract

Tannins are natural antioxidants found in plant-based foods and beverages, whose amphiphilic nature could be useful to both stabilize emulsions and protect unsaturated lipids from oxidation. In this paper, the use of tannins as antioxidant emulsifiers was studied. The main parameters influencing the stability of emulsions (i.e. tannins structure and concentration, aqueous phase pH, and ionic strength) were identified and optimized. Oil in water emulsions stabilized with tannins were compared with those stabilized with two commercial emulsifying agents, poly(vinyl alcohol) (PVA) and polyoxyethylene hydrogenated castor oil. In optimized conditions, the condensed tannins allowed to obtain a stability equivalent to that of PVA. Tannins presented good antioxidant activity in oil in water emulsion, as measured by the conjugated autoxidizable triene (CAT) assay.

Published
2015
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8. White wine proteins: how does the pH affect their conformation at room temperature?

Author

Aude Vernhet, Marie Dufrechou, Pierre Roblin, Céline Poncet-Legrand, Francois Xavier Sauvage, Sciences Pour l'Oenologie (SPO), Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro), Département Caractérisation et Elaboration des Produits Issus de l'Agriculture (CEPIA), Institut National de la Recherche Agronomique (INRA), Synchrotron SOLEIL, Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), and Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)

Subjects
[SDV.SA]Life Sciences [q-bio]/Agricultural sciences, Circular dichroism, Protein Conformation, Wine, 01 natural sciences, Fluorescence spectroscopy, 0404 agricultural biotechnology, Electrochemistry, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, General Materials Science, Spectroscopy, biology, Small-angle X-ray scattering, Chemistry, Circular Dichroism, 010401 analytical chemistry, Temperature, Proteins, food and beverages, 04 agricultural and veterinary sciences, Surfaces and Interfaces, Hydrogen-Ion Concentration, Condensed Matter Physics, 040401 food science, Protein tertiary structure, 0104 chemical sciences, Crystallography, Invertase, Spectrometry, Fluorescence, White Wine, Chitinase, biology.protein
Abstract

Our studies focused on the determination of aggregation mechanisms of proteins occurring in wine at room temperature. Even if the wine pH range is narrow (2.8 to 3.7), some proteins are affected by this parameter. At low pH, the formation of aggregates and the development of a haze due to proteins sometimes occur. The objective of this work was to determine if the pH impacted the conformational stability of wine proteins. Different techniques were used: circular dichroism and fluorescence spectroscopy to investigate the modification of their secondary and tertiary structure and also SAXS to determine their global shape. Four pure proteins were used, two considered to be stable (invertase and thaumatin-like proteins) and two considered to be unstable (two chitinase isoforms). Two pH values were tested to emphasize their behavior (pH 2.5 and 4.0). The present work highlighted the fact that the conformational stability of some wine proteins (chitinases) was impacted by partial modifications, related to the exposure of some hydrophobic sites. These modifications were enough to destabilize the native state of the protein. These modifications were not observed on wine proteins determined to be stable (invertase and thaumatin-like proteins).

Published
2013
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9. Stability of white wine proteins: combined effect of pH, ionic strength, and temperature on their aggregation

Author

Marie Dufrechou, Céline Poncet-Legrand, Francois Xavier Sauvage, Aude Vernhet, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)

Subjects
Haze, white wine, Wine, 01 natural sciences, Colloid, 0404 agricultural biotechnology, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, technique de fermentation, Plant Proteins, Chromatography, wine protein stability, haze formation, Chemistry, pH, vin blanc, Protein Stability, 010401 analytical chemistry, Intermolecular force, Osmolar Concentration, Temperature, food and beverages, 04 agricultural and veterinary sciences, General Chemistry, Hydrogen-Ion Concentration, 040401 food science, 0104 chemical sciences, Isoelectric point, Chemical engineering, oenologie, Ionic strength, White Wine, Intramolecular force, General Agricultural and Biological Sciences, ionic strength
Abstract

Protein haze development in white wines is an unacceptable visual defect attributed to slow protein unfolding and aggregation. It is favored by wine exposure to excessive temperatures but can also develop in properly stored wines. In this study, the combined impact of pH (2.5-4.0), ionic strength (0.02-0.15 M), and temperature (25, 40, and 70 °C) on wine protein stability was investigated. The results showed three classes of proteins with low conformational stability involved in aggregation at room temperature: β-glucanases, chitinases, and some thaumatin-like protein isoforms (22-24 kDa). Unexpectedly, at 25 °C, maximum instability was observed at the lower pH, far from the protein isoelectric point. Increasing temperatures led to a shift of the maximum haze at higher pH. These different behaviors could be explained by the opposite impact of pH on intramolecular (conformational stability) and intermolecular (colloidal stability) electrostatic interactions. The present results highlight that wine pH and ionic strength play a determinant part in aggregation mechanisms, aggregate characteristics, and final haze.

Published
2012
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10. Characterization of oxidized tannins: comparison of depolymerization methods, asymmetric flow field-flow fractionation and small-angle X-ray scattering

Author

Céline Poncet-Legrand, Aude Vernhet, Hélène Fulcrand, Eric Dubreucq, Bernard Cabane, Stéphane Dubascoux, Sciences Pour l'Oenologie (SPO), Université Montpellier 1 (UM1)-Institut de Recherche pour le Développement (IRD [Nouvelle-Calédonie])-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Ingénierie des Agro-polymères et Technologies Émergentes (UMR IATE), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Physique et mécanique des milieux hétérogenes (PMMH), Centre National de la Recherche Scientifique (CNRS)-ESPCI ParisTech-Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC), Agropolis foundation, Université Montpellier 1 (UM1)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université Montpellier 2 - Sciences et Techniques (UM2)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), and Centre de Coopération Internationale en Recherche Agronomique pour le Développement (Cirad)-Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro)

Subjects
oxidation, [SDV]Life Sciences [q-bio], Inorganic chemistry, aliment, goût, solvant, 02 engineering and technology, Fractionation, drink, gustation, 01 natural sciences, Biochemistry, détermination du poids moléculaire, boisson, Analytical Chemistry, tannin, Polymerization, molecular weight determination, X-Ray Diffraction, Scattering, Small Angle, Organic chemistry, depolymerization, Vitis, Solubility, couleur, tanin, Small-angle X-ray scattering, Chemistry, Depolymerization, 010401 analytical chemistry, oxydation, 021001 nanoscience & nanotechnology, Fractionation, Field Flow, 0104 chemical sciences, color, Asymmetric flow field flow fractionation, foodstuff, Proanthocyanidin, Polyphenol, small-angle X-ray scattering, Seeds, AF4-MALLS, Molar mass distribution, 0210 nano-technology, dépolymérisation, Oxidation-Reduction, Tannins
Abstract

Axe 4 Biotechnologie microbienne et enzymatique des lipides et des agropolymères e-mail: poncetc@supagro.inra.fr; Condensed tannins are a major class of plant polyphenols. They play an important part in the colour and taste of foods and beverages. Due to their chemical reactivity, tannins are not stable once extracted from plants. A number of chemical reactions can take place, leading to structural changes of the native structures to give so-called derived tannins and pigments. This paper compares results obtained on native and oxidized tannins with different techniques: depolymerization followed by high-performance liquid chromatography analysis, small-angle X-ray scattering (SAXS) and asymmetric flow field-flow fractionation (AF4). Upon oxidation, new macromolecules were formed. Thioglycolysis experiments showed no evidence of molecular weight increase, but thioglycolysis yields drastically decreased. When oxidation was performed at high concentration (e.g., 10 gL−1), the weight average degree of polymerization determined from SAXS increased, whereas it remained stable when oxidation was done at low concentration (0.1 gL−1), indicating that the reaction was intramolecular, yet the conformations were different. Differences in terms of solubility were observed; ethanol being a better solvent than water. We also separated soluble and non-water-soluble species of a much oxidized fraction. Thioglycolysis showed no big differences between the two fractions, whereas SAXS and AF4 showed that insoluble macromolecules have a weight average molecular weight ten times higher than the soluble ones.

Published
2011
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11. Tannin oxidation: intra- versus intermolecular reactions

Author

Aude Vernhet, Hélène Fulcrand, Stéphanie Carrillo, Javier Pérez, Bernard Cabane, Ana-Belen Bautista-Ortin, Céline Poncet-Legrand, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Synchrotron SOLEIL, and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)

Subjects
Polymers and Plastics, Polymers, [SDV]Life Sciences [q-bio], Bioengineering, Degree of polymerization, 01 natural sciences, Polymerization, Biomaterials, chemistry.chemical_compound, 0404 agricultural biotechnology, Polymer chemistry, Scattering, Small Angle, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Materials Chemistry, Organic chemistry, Vitis, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Chromatography, High Pressure Liquid, chemistry.chemical_classification, Molecular Structure, Depolymerization, Small-angle X-ray scattering, 010401 analytical chemistry, fungi, Water, 04 agricultural and veterinary sciences, Polymer, 040401 food science, 0104 chemical sciences, Monomer, chemistry, Thiolysis, Solubility, Malus, Oxidation-Reduction, Tannins, Macromolecule
Abstract

International audience; Grape and apple condensed tannin fractions were autoxidized at high concentrations (5 g/L) in aqueous solutions and analyzed by thiolysis (depolymerization followed by HPLC analysis) and small angle X-ray scattering (SAXS). Structural parameters of native (unoxidized) tannin polymers were derived from SAXS according to the wormlike chain model: the length per monomer is 15 A, the length of the statistical segment 17 A, and the cross section of the macromolecule has a radius within the range 3-4.5 A. The rather short length of the statistical segment is an effect of the different location of interflavanol linkages, which cause a loss of orientational correlation between successive monomers. Oxidation created new bonds that were resistant to thiolysis, and, according to thiolysis, some of these new bonds were intramolecular. However, according to SAXS, oxidation at high tannin concentration caused the weight average degree of polymerization to increase, indicating that intermolecular reactions took place as well, creating larger macromolecules. In the case of the smaller grape seed tannins, these intermolecular reactions took place "end to end" leading to the formation of longer linear macromolecules, at least in the earlier stages of oxidation. In the case of the larger apple tannins, the SAXS patterns were characteristic of larger branched macromolecules. Accordingly, the intermolecular reactions were mainly "end to middle". This is in agreement with the higher probabilities of "end to middle" reactions arising from a higher ratio extension unit/terminal unit in the latter case.

Published
2010
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12. Flavanols, Flavonols and Dihydroflavonols

Author

Véronique Cheynier, Céline Poncet-Legrand, Nancy Terrier, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)

Subjects
0106 biological sciences, chemistry.chemical_classification, [SDV]Life Sciences [q-bio], 010401 analytical chemistry, 01 natural sciences, 0104 chemical sciences, chemistry.chemical_compound, Flavonols, chemistry, White Wine, Grape wine, Food science, [CHIM.OTHE]Chemical Sciences/Other, Glyoxylic acid, Grape seed, 010606 plant biology & botany
Published
2008
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13. Aggregation of a proline-rich protein induced by epigallocatechin gallate and condensed tannins: Effect of protein glycosylation

Author

Céline Poncet-Legrand, Bernard Cabane, Aude Vernhet, Christine Pascal, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), and Centre National de la Recherche Scientifique (CNRS)

Subjects
Glycosylation, Light, Proline, Epigallocatechin gallate, Protein aggregation, 01 natural sciences, Catechin, FLAVAN-3-OLS, chemistry.chemical_compound, 0404 agricultural biotechnology, Dynamic light scattering, Drug Stability, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Humans, Scattering, Radiation, Proanthocyanidins, Vitis, Colloids, Salivary Proteins and Peptides, Chemistry, Small-angle X-ray scattering, X-Rays, GLYCOSYLATION, 010401 analytical chemistry, PROLINE-RICH PROTEIN, food and beverages, 04 agricultural and veterinary sciences, General Chemistry, 040401 food science, 0104 chemical sciences, Solutions, Monomer, Proanthocyanidin, Biochemistry, Polyphenol, Seeds, General Agricultural and Biological Sciences, EGCG, SMALL-ANGLE X-RAY SCATTERING, DYNAMIC LIGHT SCATTERING
Abstract

Correspondance: vernhet@supagro.inra.fr; International audience; Astringency is one of the most important organoleptic qualities of numerous beverages, including red wines. It is generally thought to originate from interactions between tannins and salivary proline-rich proteins (PRPs). In this work interactions between a glycosylated PRP, called II-1, and flavan-3-ols were studied in aqueous solutions and at a colloidal level, by dynamic light scattering (DLS) and small-angle X-ray scattering (SAXS). The flavan-3-ols were a monomer, epigallocatechin gallate (EGCG), and polymerized flavan-3-ol fractions extracted from grape seeds. In aqueous solutions containing EGCG and protein II-1, protein aggregation took place when protein concentration and the EGCG/protein ratio exceeded a threshold. The aggregates had a small size, comparable with the dimensions of protein monomers, and formed stable dispersions (no phase separation). Most proteins remained free in solution. This behavior is in sharp contrast with the phase separation observed for nonglycoslated PRP in the same conditions. Moreover, this slight aggregation of II-I in the presence of EGCG was disrupted by the addition of 12% ethanol. Increasing the flavan-3-ol molecular weight strongly enhanced II-I/tannin aggregation: the threshold was at a lower protein concentration (0.2 mg/mL) and a lower tannin/protein ratio. Still, in most cases, and in contrast with that observed with a nonglycosylated PRP, the aggregates remained of discrete size and stable. Only at low ethanol content (2%) did the addition of tannin polymers finally lead to phase separation, which occurred when the molar ratio of tannins to proteins exceeded 12. This systematic effect of ethanol confirmed the strong effect of cosolvents on protein/tannin interactions

Published
2008
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14. Poly(l-proline) interactions with flavan-3-ols units: Influence of the molecular structure and the polyphenol/protein ratio

Author

A. Edelmann, Aude Vernhet, Céline Poncet-Legrand, Damien Cartalade, Pascale Sarni-Manchado, Jean-Luc Putaux, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Institute of Chemical Technologies and Analytics, Vienna University of Technology (TU Wien), Centre de Recherches sur les Macromolécules Végétales (CERMAV), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), Vienna University of Technology, Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), Université Montpellier 1 (UM1)-Institut National de la Recherche Agronomique (INRA)-Université de Montpellier (UM)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)

Subjects
Stereochemistry, General Chemical Engineering, Epigallocatechin gallate, 01 natural sciences, CRYO-TEM, chemistry.chemical_compound, 0404 agricultural biotechnology, Dynamic light scattering, Flavan, Polymer chemistry, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Proline, WINE TANNIN, 010401 analytical chemistry, PROLINE-RICH PROTEIN, Catechin, 04 agricultural and veterinary sciences, General Chemistry, 040401 food science, 0104 chemical sciences, Monomer, Epicatechin gallate, chemistry, Polyphenol, DYNAMIC LIGHT SCATTERING, Food Science
Abstract

International audience; The interaction of proline-rich proteins with flavan-3-ol monomers was studied using poly(L-proline) as a model. Several parameters were varied: (i) the galloylation and trihydroxylation of the flavan-3-ols and (ii) the polyphenol/protein ratio. The systems were characterized by means of UV-Vis spectroscopy, dynamic light scattering and cryo-electron microscopy. Strong differences were observed between epicatechin and epigallocatechin, that did not form aggregates with poly(L-proline), and epicatechin gallate, epigallocatechin gallate, and catechin, which did. This highlighted the strong influence of structural details on the interactions. When complexes were formed, their stability depended on the monomer/protein ratio and on the initial protein concentration. For low galloylated flavan-3-ol/protein ratios (up to 17) and low poly(L-proline) concentration (0.03 mM), interactions led to the formation of relatively stable particles (average hydrodynamic diameter between 30 and 120 nm). When the ratio was further increased to 27, the particles formed were less stable and equilibrium was reached after a longer time. For the highest ratios (27 and 33), aggregation finally led to precipitation. Increasing the protein concentration (1.06 mM) strongly enhanced polyphenol-protein complexation, resulting in much larger particles and more extensive precipitation

Published
2006
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15. Hybrid Dissymmetrical Colloidal Particles

Author

Etienne Duguet, Stéphane Reculusa, Serge Ravaine, Christophe Mingotaud, Elodie Bourgeat-Lami, Céline Poncet-Legrand, Adeline Perro, Centre de recherches Paul Pascal (CRPP), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de la Matière Condensée de Bordeaux (ICMCB), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut Polytechnique de Bordeaux-Université de Bordeaux (UB), Laboratoire de chimie et procédés de polymérisation (LCPP), Centre National de la Recherche Scientifique (CNRS)-École Supérieure Chimie Physique Électronique de Lyon, Interactions moléculaires et réactivité chimique et photochimique (IMRCP), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD), Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Université Fédérale Toulouse Midi-Pyrénées, Université de Bordeaux (UB)-Institut Polytechnique de Bordeaux-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), École Supérieure de Chimie Physique Électronique de Lyon (CPE)-Centre National de la Recherche Scientifique (CNRS), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Fédération de Recherche Fluides, Energie, Réacteurs, Matériaux et Transferts (FERMAT), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), and Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, General Chemical Engineering, Dispersity, Emulsion polymerization, Nanoparticle, Latex-particles, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Monodisperse, Styrene, Polymerization, chemistry.chemical_compound, Adsorption, Polymer chemistry, Suspension, Materials Chemistry, Silica spheres, Shape, General Chemistry, [CHIM.MATE]Chemical Sciences/Material chemistry, 021001 nanoscience & nanotechnology, Macromonomer, 0104 chemical sciences, chemistry, Chemical engineering, Seeded emulsion, Nanoparticles, Polystyrene, 0210 nano-technology
Abstract

International audience; Colloidal particles with a controlled morphology combining both organic and inorganic parts were synthesized through a seeded emulsion polymerization process. Silica seed particles from 50 to 150 nm were first surface-modified by adsorption of an oxyethylene-based macromonomer or covalent grafting of a trialkoxysilane derivative. Then, emulsion polymerization of styrene was carried out in the presence of these particles, the formation of polystyrene nodules being highly favored at the silica surface in such conditions. While varying different experimental parameters, we have demonstrated that the ratio between the number of silica seeds and the number of growing nodules is a key parameter in controlling the morphology of the final hybrid nanoparticles. For instance, in the particular case when this ratio was close to 1, dumbbell-like or snowman-like particles were obtained. Further selective surface modification of their silica moiety was also tested successfully, indicating a potential application of these hybrid particles as original building blocks toward supraparticulate assemblies

Published
2005
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16. Structure determination and color properties of a new directly linked flavanol-anthocyanin dimer

Author

Christine Le Guernevé, Erika Salas, Véronique Cheynier, Hélène Fulcrand, Céline Poncet-Legrand, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)

Subjects
Dimer, 01 natural sciences, Biochemistry, chemistry.chemical_compound, 0404 agricultural biotechnology, pigment, Drug Discovery, Polymer chemistry, Taxifolin, Organic chemistry, Moiety, Copigmentation, Equilibrium constant, [CHIM.ORGA]Chemical Sciences/Organic chemistry, 010401 analytical chemistry, Organic Chemistry, 04 agricultural and veterinary sciences, 040401 food science, Malvidin, anthocyanins, 0104 chemical sciences, 3. Good health, flavanol, chemistry, Covalent bond, Anthocyanin
Abstract

International audience; The structure of catechin-(4alpha-->8)-malvidin 3-O-glucoside obtained by reaction of taxifolin and malvidin 3-O-glucoside following a protocol adapted from proanthocyanidin dimer synthesis was determined by NMR spectrometry. Incorporation of the anthocyanin moiety into a covalent linked flavanol-anthocyanin dimer did not modify its colour properties (i.e., hydration equilibrium constant and copigmentation).

Published
2004
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17. Demonstration of the occurrence of flavanol–anthocyanin adducts in wine and in model solutions

Author

Céline Poncet-Legrand, Erika Salas, Jean-Paul Mazauric, Véronique Cheynier, Vessela Atanasova, Emmanuelle Meudec, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA)

Subjects
MODEL SOLUTION, PIGMENT, THIOLYSIS, Carbocation, 01 natural sciences, Biochemistry, Medicinal chemistry, ADDUCT, Analytical Chemistry, Adduct, chemistry.chemical_compound, 0404 agricultural biotechnology, [CHIM.ANAL]Chemical Sciences/Analytical chemistry, Environmental Chemistry, Organic chemistry, Moiety, Spectroscopy, Wine, Nucleophilic addition, PROCYANIDIN, 010401 analytical chemistry, food and beverages, WINE, HPLC/MS, 04 agricultural and veterinary sciences, FLAVANOL, 040401 food science, Malvidin, 0104 chemical sciences, CHIMIE ANALYTIQUE, Thiolysis, chemistry, ANTHOCYANIN, Procyanidin dimer
Abstract

Flavanol–anthocyanin (F–A+) adducts were detected in red wine. A mechanism involving acid-catalysed cleavage of flavanol oligomers followed by nucleophilic addition of the anthocyanin moiety (in its hemiketal form) to the resulting carbocation (F+) was postulated. To confirm this mechanism, reactions between malvidin 3-O-glucoside (Mv3glc) and procyanidin dimer epicatechin-(4-8)-epicatechin 3-O-gallate (B2-3′OG) were studied in a model solution system at pH 2. A new pigment with a UV-Vis spectrum similar to that of Mv3glc and a signal at m/z=781 in the positive ion mode was detected and was attributed to Ec–Mv3glc, in agreement with the proposed reaction pathway. A protocol adapted from the synthesis of procyanidin dimers, in which the terminal flavanol units was replaced with Mv3glc, was tested. Two new pigments were formed with a signal at m/z=781, in the positive ion mode. These ions were attributed to catechin–Mv3glc. Both adducts obtained by hemisynthesis showed exactly the same fragmentation pattern as that present in wine. In particular, the loss of a 126 amu fragment corresponding to the unsubstituted A-ring of the flavanol unit indicated that all of them were (epi)catechin–Mv3glc adducts. These results prove that reactions between the carbocations resulting from cleavage of tannin interflavanic bonds and anthocyanins occur in wine.

Published
2004
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18. Solution Properties of Hydrophobically-modified Copolymers of N-Isopropylacrylamide and N-L-Valine Acrylamide: A Study by Fluorescence Spectroscopy and Microcalorimetry

Author

Céline Poncet-Legrand, Françoise M. Winnik, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), and Université de Montréal (UdeM)

Subjects
Isothermal microcalorimetry, Polymers and Plastics, [SDV]Life Sciences [q-bio], 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Fluorescence spectroscopy, chemistry.chemical_compound, N-isopropylacrylamide copolymer, Polymer chemistry, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Materials Chemistry, Copolymer, [SPI.GPROC]Engineering Sciences [physics]/Chemical and Process Engineering, Ionomer, cloud point, Cloud point, Aqueous solution, Chemistry, pyrene, polymeric micelle, 021001 nanoscience & nanotechnology, microcalorimetry, amphiphilic polyelectrolyte, 0104 chemical sciences, Acrylamide, Pyrene, 0210 nano-technology
Abstract

International audience; Copolymers of N-( isopropylacrylamide) (NIPAM, 90 mol%) and N-L-valine acrylamide (Val, 10 mol%), as well as their hydrophobically-modified copolymers, namely a copolymer of NIPAM, Val, and N-n-octadecylacrylamide (PNIPAM-Val-C-18, 1 mol%) and a copolymer of NIPAM, Val, and N-[4-( 1-pyrenyl)butyl]-N-n-octadecylacrylamide (PNIPAM-Val-C18Py, 1 mol%) were prepared by free radical copolymerization of the respective monomers. Studies by turbidimetry, microcalorimetry, dynamic light scattering, and fluorescence spectroscopy indicated that the hydrophobically-modified copolymers form polymeric micelles in water (effective hydrodynamic diameter: 25 nm +/- 5 nm). Solutions of all the copolymers underwent pH-dependent phase separation upon heating, but the pH- or temperature-stimulated coil-to-globule collapse/chain expansion did not result in complete disruption of the hydrophobic microdomains.

Published
2001
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19. Interactions between flavan-3-ols and poly(L-proline) studied by isothermal titration calorimetry: effect of the tannin structure

Author

Véronique Cheynier, Anne Imberty, Catherine Gautier, Céline Poncet-Legrand, Sciences Pour l'Oenologie (SPO), Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Université Montpellier 1 (UM1)-Université de Montpellier (UM)-Institut National de la Recherche Agronomique (INRA), Centre de Recherches sur les Macromolécules Végétales (CERMAV), Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Université Joseph Fourier - Grenoble 1 (UJF), and Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Isothermal microcalorimetry, Calorimetry, Epigallocatechin gallate, Degree of polymerization, Hydroxylation, 01 natural sciences, Oligomer, chemistry.chemical_compound, 0404 agricultural biotechnology, Gallic Acid, Polymer chemistry, [SDV.IDA]Life Sciences [q-bio]/Food engineering, Organic chemistry, ComputingMilieux_MISCELLANEOUS, Flavonoids, TITRATION MICROCALORIMETRY, 010401 analytical chemistry, PROLINE-RICH PROTEIN, Isothermal titration calorimetry, 04 agricultural and veterinary sciences, General Chemistry, 040401 food science, 0104 chemical sciences, Monomer, Epicatechin gallate, chemistry, Thermodynamics, General Agricultural and Biological Sciences, Peptides, Tannins, INTERACTION, TANNIN
Abstract

International audience; Interactions of proline-rich proteins (PRPs) with flavan-3-ols was studied using poly(L-proline) as a model protein by means of isothermal titration calorimetry (ITC). Several parameters were varied: (i) the galloylation and B-ring trihydroxylation of the flavan-3-ols (catechin, epicatechin, epicatechin gallate, and epigallocatechin gallate) and (ii) the degree of polymerization (monomers were compared to a mixture of oligomers with average degree of polymerization of 3.85). Large differences were observed between the flavan-3-ol monomers: no enthalpy change was measured when catechin and epicatechin were titrated by poly(L-proline), whereas thermodynamic parameters were determined in the case of galloylated monomers and mixture of oligomers. Stoichiometry ranged from 1 oligomer bound for each 12 proline units to 1 galloylated monomer for each 8 or 10 proline units. Association constants were in the range of 10(4)-10(5) M-1, indicating a relatively high affinity of galloylated flavanols toward poly(L-proline), and the coexistence of both enthalpy- and entropy-driven phenomena was suggested. Finally, the binding of grape seed tannins to proteins was shown to be a cooperative process

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