The Experts below are selected from a list of 3408 Experts worldwide ranked by ideXlab platform

Laetitia Mouls - One of the best experts on this subject based on the ideXlab platform.

  • Detection and Identification of Oxidation Markers of the Reaction of Grape Tannins with Volatile Thiols Commonly Found in Wine.
    Journal of agricultural and food chemistry, 2021
    Co-Authors: Lucas Suc, Peggy Rigou, Laetitia Mouls
    Abstract:

    Condensed tannins undergo many modifications during winemaking and the aging of wine. These reactions take place between the various constituent units of the tannins as well with other types of molecules present in wines. This work aimed to highlight the potential reactions of tannins and aromas. After the monomeric standards of the reaction products were synthesized, the study of the reactivity of tannins (dimer B2, trimer C1, and grape seed tannins composed of 23% epicatechin-3-O-gallate) with aromas (3-sufanylhexan-1-ol, 4-methyl-4-sulfanylpentan-2-one, ethanethiol, and furfurylthiol) permitted identification of numerous reaction products. These tannin/aroma oxidation markers, detected after Chemical Depolymerization, allow for progress in the characterization of tannins in the oenological environment and the understanding of their reactivity toward the molecules present in the samples. A better characterization of tannins will make it possible to better measure the impact of these modifications on the organoleptic qualities of wines.

  • The use of extracted‐ion chromatograms to quantify the composition of condensed tannin subunits
    Rapid Communications in Mass Spectrometry, 2020
    Co-Authors: Julien Giribaldi, Lucas Suc, Hélène Fulcrand, Martin Besson, Laetitia Mouls
    Abstract:

    Rationale: The analysis of tannins is currently usually done by liquid chromatography after the Chemical Depolymerization of tannins. However, one of the main limitations of this method is the difficulty in specifically detecting each constitutive tannin monomer in a complex matrix, as numerous compounds co-elute with the monomers, thereby compromising the analysis. Methods: The Depolymerization of tannins under acidic conditions and in the presence of thioglycolic acid releases the various constitutive monomers, either as terminal units or as extension units. The tannin subunits were then quantified using extracted-ion chromatogram (EIC) mass spectrometry, which required the determination of the ionization efficiency of the monomers. Thus, we used AgBF4-assisted coupling for the hemisynthesis of the noncommercial epicatechin gallate dimer. Results: The EIC showed that the derivatives of the extension units were twice as ionized as the terminal units. Unlike the UV chromatograms, this new EIC-based method is more specific and accurate because it is not impacted by the co-elution phenomenon. This result, when added to the linearity obtained on a large range of the calibration curves, allowed for quantification of tannin subunits from EIC in complex mixtures with less pretreatment of the samples. Conclusions: Due to its specificity and sensitivity, this EIC-based method represents a significant step toward improving the quantification of the tannin composition of samples. The results of this study should allow the oxidation markers to be quantified more accurately and taken into account, thereby providing a better indication of the actual tannin composition.

  • The use of extracted-ion chromatograms to quantify the composition of condensed tannin subunits.
    Rapid communications in mass spectrometry : RCM, 2020
    Co-Authors: Julien Giribaldi, Lucas Suc, Hélène Fulcrand, Martin Besson, Laetitia Mouls
    Abstract:

    Rationale The analysis of tannins is currently usually done by liquid chromatography after the Chemical Depolymerization of tannins. However, one of the main limitations of this method is the difficulty in specifically detecting each constitutive tannin monomer in a complex matrix, as numerous compounds co-elute with the monomers, thereby compromising the analysis. Methods The Depolymerization of tannins under acidic conditions and in the presence of thioglycolic acid releases the various constitutive monomers, either as terminal units or as extension units. The tannin subunits were then quantified using extracted-ion chromatogram (EIC) mass spectrometry, which required the determination of the ionization efficiency of the monomers. Thus, we used AgBF4-assisted coupling for the hemisynthesis of the noncommercial epicatechin gallate dimer. Results The EIC showed that the derivatives of the extension units were twice as ionized as the terminal units. Unlike the UV chromatograms, this new EIC-based method is more specific and accurate because it is not impacted by the co-elution phenomenon. This result, when added to the linearity obtained on a large range of the calibration curves, allowed for quantification of tannin subunits from EIC in complex mixtures with less pretreatment of the samples. Conclusions Due to its specificity and sensitivity, this EIC-based method represents a significant step toward improving the quantification of the tannin composition of samples. The results of this study should allow the oxidation markers to be quantified more accurately and taken into account, thereby providing a better indication of the actual tannin composition.

  • Identification of new oxidation markers of grape-condensed tannins by UPLC-MS analysis after Chemical Depolymerization
    Tetrahedron, 2015
    Co-Authors: Laetitia Mouls, Helene Fulcrand-hoh
    Abstract:

    Model solutions of oxidized monomer/dimer mixtures of flavan-3-ol (EC/B2, EGC/B2, ECG/B2, EGCG/B2) were studied after Chemical Depolymerization by UPLC-MS. New oxidation markers of condensed tannins were identified. This analytical method was applied to a wine sample and most of these oxidized markers were detected. This method will permit following the oxidation state of tannins during the winemaking process and storage in order to improve the quality of the products.

  • Identification of new oxidation markers of grape-condensed tannins by UPLC–MS analysis after Chemical Depolymerization
    Tetrahedron, 2015
    Co-Authors: Laetitia Mouls, Hélène Fulcrand
    Abstract:

    Model solutions of oxidized monomer/dimer mixtures of flavan-3-ol (EC/B2, EGC/B2, ECG/B2, EGCG/B2) were studied after Chemical Depolymerization by UPLC–MS. New oxidation markers of condensed tannins were identified. This analytical method was applied to a wine sample and most of these oxidized markers were detected. This method will permit following the oxidation state of tannins during the winemaking process and storage in order to improve the quality of the products.

Hélène Fulcrand - One of the best experts on this subject based on the ideXlab platform.

  • The use of extracted‐ion chromatograms to quantify the composition of condensed tannin subunits
    Rapid Communications in Mass Spectrometry, 2020
    Co-Authors: Julien Giribaldi, Lucas Suc, Hélène Fulcrand, Martin Besson, Laetitia Mouls
    Abstract:

    Rationale: The analysis of tannins is currently usually done by liquid chromatography after the Chemical Depolymerization of tannins. However, one of the main limitations of this method is the difficulty in specifically detecting each constitutive tannin monomer in a complex matrix, as numerous compounds co-elute with the monomers, thereby compromising the analysis. Methods: The Depolymerization of tannins under acidic conditions and in the presence of thioglycolic acid releases the various constitutive monomers, either as terminal units or as extension units. The tannin subunits were then quantified using extracted-ion chromatogram (EIC) mass spectrometry, which required the determination of the ionization efficiency of the monomers. Thus, we used AgBF4-assisted coupling for the hemisynthesis of the noncommercial epicatechin gallate dimer. Results: The EIC showed that the derivatives of the extension units were twice as ionized as the terminal units. Unlike the UV chromatograms, this new EIC-based method is more specific and accurate because it is not impacted by the co-elution phenomenon. This result, when added to the linearity obtained on a large range of the calibration curves, allowed for quantification of tannin subunits from EIC in complex mixtures with less pretreatment of the samples. Conclusions: Due to its specificity and sensitivity, this EIC-based method represents a significant step toward improving the quantification of the tannin composition of samples. The results of this study should allow the oxidation markers to be quantified more accurately and taken into account, thereby providing a better indication of the actual tannin composition.

  • The use of extracted-ion chromatograms to quantify the composition of condensed tannin subunits.
    Rapid communications in mass spectrometry : RCM, 2020
    Co-Authors: Julien Giribaldi, Lucas Suc, Hélène Fulcrand, Martin Besson, Laetitia Mouls
    Abstract:

    Rationale The analysis of tannins is currently usually done by liquid chromatography after the Chemical Depolymerization of tannins. However, one of the main limitations of this method is the difficulty in specifically detecting each constitutive tannin monomer in a complex matrix, as numerous compounds co-elute with the monomers, thereby compromising the analysis. Methods The Depolymerization of tannins under acidic conditions and in the presence of thioglycolic acid releases the various constitutive monomers, either as terminal units or as extension units. The tannin subunits were then quantified using extracted-ion chromatogram (EIC) mass spectrometry, which required the determination of the ionization efficiency of the monomers. Thus, we used AgBF4-assisted coupling for the hemisynthesis of the noncommercial epicatechin gallate dimer. Results The EIC showed that the derivatives of the extension units were twice as ionized as the terminal units. Unlike the UV chromatograms, this new EIC-based method is more specific and accurate because it is not impacted by the co-elution phenomenon. This result, when added to the linearity obtained on a large range of the calibration curves, allowed for quantification of tannin subunits from EIC in complex mixtures with less pretreatment of the samples. Conclusions Due to its specificity and sensitivity, this EIC-based method represents a significant step toward improving the quantification of the tannin composition of samples. The results of this study should allow the oxidation markers to be quantified more accurately and taken into account, thereby providing a better indication of the actual tannin composition.

  • Identification of new oxidation markers of grape-condensed tannins by UPLC–MS analysis after Chemical Depolymerization
    Tetrahedron, 2015
    Co-Authors: Laetitia Mouls, Hélène Fulcrand
    Abstract:

    Model solutions of oxidized monomer/dimer mixtures of flavan-3-ol (EC/B2, EGC/B2, ECG/B2, EGCG/B2) were studied after Chemical Depolymerization by UPLC–MS. New oxidation markers of condensed tannins were identified. This analytical method was applied to a wine sample and most of these oxidized markers were detected. This method will permit following the oxidation state of tannins during the winemaking process and storage in order to improve the quality of the products.

  • UPLC-ESI-MS study of the oxidation markers released from tannin Depolymerization: toward a better characterization of the tannin evolution over food and beverage processing.
    Journal of mass spectrometry : JMS, 2012
    Co-Authors: Laetitia Mouls, Hélène Fulcrand
    Abstract:

    Condensed tannins take an important part in the sensory quality of food and beverage. Sensory analyses are usually carried out with various tannin fractions isolated from food or beverage, and their interpretation are limited by the lack of knowledge in the fine and accurate molecular composition of the tannin fractions. Besides, the studies of the Chemical reactivity conducted in model solutions with ‘simple’ flavanols allow a better understanding of their evolution pathways, but they cannot take into account their reactivity as polymers, specifically regarding oxidation. In particular, competition between intramolecular and intermolecular reactions may strongly impact on the tannin structures (size, branching and conformation) and consequently on their properties. An ultra-performance liquid chromatography-mass spectrometry electrospray ionization mass spectrometer analytical method was thus developed in order to identify oxidized tannins generated by autoxidation. Given the difficulties to separate and detect tannins with high DP, samples were depolymerized by Chemical Depolymerization prior to analysis. Since the linkages created by oxidation are not cleavable in the usual Depolymerization conditions (contrarily to the original interflavanic linkages), specific oxidation residues are released from tannins structures after their autoxidation. Oxidation markers of both intermolecular and intramolecular mechanisms have been identified; these are mainly dimers and trimers, more or less oxidized, and some contain additional hydroxyl groups. Furthermore, the nature of the subunits (extension vs terminal) making up these dimers and trimers was clearly established. Copyright © 2012 John Wiley & Sons, Ltd.

Heikki Kallio - One of the best experts on this subject based on the ideXlab platform.

  • Suberin of potato (Solanum tuberosum var. Nikola): comparison of the effect of cutinase CcCut1 with Chemical Depolymerization.
    Journal of agricultural and food chemistry, 2009
    Co-Authors: Riikka Järvinen, Armando J. D. Silvestre, Ulla Holopainen, Mika Kaimainen, Antti Nyyssölä, Ana M. Gil, Carlos Pascoal Neto, Pekka Lehtinen, Johanna Buchert, Heikki Kallio
    Abstract:

    Chemical and enzymatic Depolymerizations of suberin isolated from potato peel (Solanum tuberosum var. Nikola) were performed under various conditions. Enzymatic hydrolysis with cutinase CcCut1 and Chemical methanolysis with NaOMe of suberin yielded monomeric fragments, which were identified as TMS derivatives with GC-MS and GC-FID. The solid, hydrolysis-resistant residues were analyzed with solid state 13C CPMAS NMR, FT-IR, and microscopic methods. Methanolysis released more CHCl3-soluble material than the cutinase treatment when determined gravimetrically. Interestingly, cutinase-catalyzed hydrolysis produced higher proportions of aliphatic monomers than hydrolysis with the NaOMe procedure when analyzed by GC in the form of TMS derivatives. Monomers released by the two methods were mainly α,ω-dioic acids and ω-hydroxy acids, but the ratios of the detected monomers were different, at 40.0 and 32.7% for methanolysis and 64.6 and 8.2% for cutinase, respectively. Thus, cutinase CcCut1 showed higher activity ...

Riikka Järvinen - One of the best experts on this subject based on the ideXlab platform.

  • Suberin of potato (Solanum tuberosum var. Nikola): comparison of the effect of cutinase CcCut1 with Chemical Depolymerization.
    Journal of agricultural and food chemistry, 2009
    Co-Authors: Riikka Järvinen, Armando J. D. Silvestre, Ulla Holopainen, Mika Kaimainen, Antti Nyyssölä, Ana M. Gil, Carlos Pascoal Neto, Pekka Lehtinen, Johanna Buchert, Heikki Kallio
    Abstract:

    Chemical and enzymatic Depolymerizations of suberin isolated from potato peel (Solanum tuberosum var. Nikola) were performed under various conditions. Enzymatic hydrolysis with cutinase CcCut1 and Chemical methanolysis with NaOMe of suberin yielded monomeric fragments, which were identified as TMS derivatives with GC-MS and GC-FID. The solid, hydrolysis-resistant residues were analyzed with solid state 13C CPMAS NMR, FT-IR, and microscopic methods. Methanolysis released more CHCl3-soluble material than the cutinase treatment when determined gravimetrically. Interestingly, cutinase-catalyzed hydrolysis produced higher proportions of aliphatic monomers than hydrolysis with the NaOMe procedure when analyzed by GC in the form of TMS derivatives. Monomers released by the two methods were mainly α,ω-dioic acids and ω-hydroxy acids, but the ratios of the detected monomers were different, at 40.0 and 32.7% for methanolysis and 64.6 and 8.2% for cutinase, respectively. Thus, cutinase CcCut1 showed higher activity ...

Helene Fulcrand-hoh - One of the best experts on this subject based on the ideXlab platform.

  • Identification of new oxidation markers of grape-condensed tannins by UPLC-MS analysis after Chemical Depolymerization
    Tetrahedron, 2015
    Co-Authors: Laetitia Mouls, Helene Fulcrand-hoh
    Abstract:

    Model solutions of oxidized monomer/dimer mixtures of flavan-3-ol (EC/B2, EGC/B2, ECG/B2, EGCG/B2) were studied after Chemical Depolymerization by UPLC-MS. New oxidation markers of condensed tannins were identified. This analytical method was applied to a wine sample and most of these oxidized markers were detected. This method will permit following the oxidation state of tannins during the winemaking process and storage in order to improve the quality of the products.

  • UPLC-ESI-MS study of the oxidation markers released from tannin Depolymerization: toward a better characterization of the tannin evolution over food and beverage processing
    Journal of Mass Spectrometry, 2012
    Co-Authors: Laetitia Mouls, Helene Fulcrand-hoh
    Abstract:

    Condensed tannins take an important part in the sensory quality of food and beverage. Sensory analyses are usually carried out with various tannin fractions isolated from food or beverage, and their interpretation are limited by the lack of knowledge in the fine and accurate molecular composition of the tannin fractions. Besides, the studies of the Chemical reactivity conducted in model solutions with simple flavanols allow a better understanding of their evolution pathways, but they cannot take into account their reactivity as polymers, specifically regarding oxidation. In particular, competition between intramolecular and intermolecular reactions may strongly impact on the tannin structures (size, branching and conformation) and consequently on their properties. An ultra-performance liquid chromatography-mass spectrometry electrospray ionization mass spectrometer analytical method was thus developed in order to identify oxidized tannins generated by autoxidation. Given the difficulties to separate and detect tannins with high DP, samples were depolymerized by Chemical Depolymerization prior to analysis. Since the linkages created by oxidation are not cleavable in the usual Depolymerization conditions (contrarily to the original interflavanic linkages), specific oxidation residues are released from tannins structures after their autoxidation. Oxidation markers of both intermolecular and intramolecular mechanisms have been identified; these are mainly dimers and trimers, more or less oxidized, and some contain additional hydroxyl groups. Furthermore, the nature of the subunits (extension vs terminal) making up these dimers and trimers was clearly established.