The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
Pralay Das - One of the best experts on this subject based on the ideXlab platform.
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supported palladium nanoparticles as switchable catalyst for aldehyde conjugate s and Acetate ester syntheses from alcohols
New Journal of Chemistry, 2017Co-Authors: Dhananjay Bhattacherjee, Vandna Thakur, Pralay Das, Sandeep Kumar, Abha ChaudharyAbstract:Polymer-supported Pd(0) (Pd@PS) nanoparticles (NPs) were explored as a switchable catalyst for oxidative aldehyde conjugate/s (AC/s) and Acetate Esters (AEs) syntheses from alcohols. Using the same substrates, the catalyst in the presence of oxygen and K2CO3 participated in AC/s synthesis, and in the presence of traces of air and NaOtBu, unusual AEs products were obtained.
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Supported palladium nanoparticles as switchable catalyst for aldehyde conjugate/s and Acetate ester syntheses from alcohols
New Journal of Chemistry, 2017Co-Authors: Sandeep Kumar, Dhananjay Bhattacherjee, Vandna Thakur, Abha Chaudhary, Bandna, Pralay DasAbstract:Polymer-supported Pd(0) (Pd@PS) nanoparticles (NPs) were explored as a switchable catalyst for oxidative aldehyde conjugate/s (AC/s) and Acetate Esters (AEs) syntheses from alcohols. Using the same substrates, the catalyst in the presence of oxygen and K2CO3 participated in AC/s synthesis, and in the presence of traces of air and NaOtBu, unusual AEs products were obtained.
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Oxidative “reverse-esterification” of ethanol with benzyl/alkyl alcohols or aldehydes catalyzed by supported rhodium nanoparticles
Green Chemistry, 2016Co-Authors: Nitul Ranjan Guha, Saurabh Sharma, Dhananjay Bhattacherjee, Vandna Thakur, Richa Bharti, C. Bal Reddy, Pralay DasAbstract:A very unusual role of polystyrene stabilized rhodium (Rh@PS) nanoparticles as a supported catalyst is described for “reverse-esterification” of ethanol with benzyl/alkyl alcohols or aldehydes. Faster and selective oxidation of ethanol to acetaldehyde and H2 under Rh@PS catalyzed conditions which restricted further oxidation of benzyl/alkyl alcohols and their in situ reaction gave the corresponding Acetate Esters following the dehydrogenative-coupling approach. A hitherto redox dehydrogenative-coupling of ethanol and aldehydes has also been explored for the same Acetate ester synthesis under Rh@PS catalyzed conditions.
S. Shekarsaraee - One of the best experts on this subject based on the ideXlab platform.
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Comparative Study of Liquid-Liquid Phase Equilibria of the Type-II systems [Water + Carboxylic Acids (C5 and C6) + Acetate Esters]: Measurement and Correlation
Industrial & Engineering Chemistry Research, 2020Co-Authors: A. Ghanadzadeh Gilani, Elham Nasiri-touli, H. Ghanadzadeh Gilani, S. ShekarsaraeeAbstract:A study on the type-2 liquid-liquid equilibrium (LLE) behavior of the {water + valeric or caproic acids + Acetate Esters (n-propyl, isopropyl, n-amyl, and n-hexyl Acetates)} ternary systems was performed at T = 298.2 K and p = 101.3 kPa. Solubility and tie line data were experimentally determined using cloud point and HPLC methods, respectively. The results were validated through acid-base and Karl-Fisher titrator methods. The quality of the experimental tie lines was checked using the Hand equation. For these systems, the thermodynamic models of NRTL and UNIQUAC were successfully applied to fit the experimental tie lines and the values of the binary interaction parameters were obtained. Evaluation of the solvents capacity was performed using the calculation of distribution coefficients and separation factors. The influence of chemical structure of the chosen Esters on the immiscibility region was found to be almost small. As a result, all the chosen Acetate Esters have relatively high separation factors ...
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comparative study of liquid liquid phase equilibria of the type ii systems water carboxylic acids c5 and c6 Acetate Esters measurement and correlation
Industrial & Engineering Chemistry Research, 2020Co-Authors: Ghanadzadeh A Gilani, Elham Nasiritouli, Ghanadzadeh H Gilani, S. ShekarsaraeeAbstract:A study on the type-2 liquid-liquid equilibrium (LLE) behavior of the {water + valeric or caproic acids + Acetate Esters (n-propyl, isopropyl, n-amyl, and n-hexyl Acetates)} ternary systems was performed at T = 298.2 K and p = 101.3 kPa. Solubility and tie line data were experimentally determined using cloud point and HPLC methods, respectively. The results were validated through acid-base and Karl-Fisher titrator methods. The quality of the experimental tie lines was checked using the Hand equation. For these systems, the thermodynamic models of NRTL and UNIQUAC were successfully applied to fit the experimental tie lines and the values of the binary interaction parameters were obtained. Evaluation of the solvents capacity was performed using the calculation of distribution coefficients and separation factors. The influence of chemical structure of the chosen Esters on the immiscibility region was found to be almost small. As a result, all the chosen Acetate Esters have relatively high separation factors ...
Sylvie Dequin - One of the best experts on this subject based on the ideXlab platform.
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Integrating transcriptomics and metabolomics for the analysis of the aroma profiles of Saccharomyces cerevisiae strains from diverse origins
BMC genomics, 2017Co-Authors: Inês Mendes, Isabelle Sanchez, Ricardo Franco-duarte, Carole Camarasa, Dorit Elisabeth Schuller, Sylvie Dequin, Maria João SousaAbstract:During must fermentation thousands of volatile aroma compounds are formed, with higher alcohols, Acetate Esters and ethyl Esters being the main aromatic compounds contributing to floral and fruity aromas. The action of yeast, in particular Saccharomyces cerevisiae, on the must components will build the architecture of the wine flavour and its fermentation bouquet. The objective of the present work was to better understand the molecular and metabolic bases of aroma production during a fermentation process. For such, comparative transcriptomic and metabolic analysis was performed at two time points (5 and 50 g/L of CO2 released) in fermentations conducted by four yeast strains from different origins and/or technological applications (cachaca, sake, wine, and laboratory), and multivariate factorial analyses were used to rationally identify new targets for improving aroma production. Results showed that strains from cachaca, sake and wine produced higher amounts of Acetate Esters, ethyl Esters, acids and higher alcohols, in comparison with the laboratory strain. At fermentation time T1 (5 g/L CO2 released), comparative transcriptomics of the three S. cerevisiae strains from different fermentative environments in comparison with the laboratory yeast S288c, showed an increased expression of genes related with tetracyclic and pentacyclic triterpenes metabolism, involved in sterol synthesis. Sake strain also showed upregulation of genes ADH7 and AAD6, involved in the formation of higher alcohols in the Ehrlich pathway. For fermentation time point T2 (50 g/L CO2 released), again sake strain, but also VL1 strain, showed an increased expression of genes involved in formation of higher alcohols in the Ehrlich pathway, namely ADH7, ADH6 and AAD6, which is in accordance with the higher levels of methionol, isobutanol, isoamyl alcohol and phenylethanol observed. Our approach revealed successful to integrate data from several technologies (HPLC, GC-MS, microarrays) and using different data analysis methods (PCA, MFA). The results obtained increased our knowledge on the production of wine aroma and flavour, identifying new gene in association to the formation of flavour active compounds, mainly in the production of fatty acids, and ethyl and Acetate Esters.
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Integrating transcriptomics and metabolomics for the analysis of the aroma profiles of Saccharomyces cerevisiae strains from diverse origins
BMC Genomics, 2017Co-Authors: Inês Mendes, Isabelle Sanchez, Ricardo Franco-duarte, Carole Camarasa, Sylvie Dequin, Dorit Schuller, Maria João SousaAbstract:Background: During must fermentation thousands of volatile aroma compounds are formed, with higher alcohols, Acetate Esters and ethyl Esters being the main aromatic compounds contributing to floral and fruity aromas. The action of yeast, in particular Saccharomyces cerevisiae, on the must components will build the architecture of the wine flavour and its fermentation bouquet. The objective of the present work was to better understand the molecular and metabolic bases of aroma production during a fermentation process. For such, comparative transcriptomic and metabolic analysis was performed at two time points (5 and 50 g/L of CO2 released) in fermentations conducted by four yeast strains from different origins and/or technological applications (cacha double dagger a, sake, wine, and laboratory), and multivariate factorial analyses were used to rationally identify new targets for improving aroma production. Results: Results showed that strains from cacha double dagger a, sake and wine produced higher amounts of Acetate Esters, ethyl Esters, acids and higher alcohols, in comparison with the laboratory strain. At fermentation time T1 (5 g/L CO2 released), comparative transcriptomics of the three S. cerevisiae strains from different fermentative environments in comparison with the laboratory yeast S288c, showed an increased expression of genes related with tetracyclic and pentacyclic triterpenes metabolism, involved in sterol synthesis. Sake strain also showed upregulation of genes ADH7 and AAD6, involved in the formation of higher alcohols in the Ehrlich pathway. For fermentation time point T2 (50 g/L CO2 released), again sake strain, but also VL1 strain, showed an increased expression of genes involved in formation of higher alcohols in the Ehrlich pathway, namely ADH7, ADH6 and AAD6, which is in accordance with the higher levels of methionol, isobutanol, isoamyl alcohol and phenylethanol observed. Conclusions: Our approach revealed successful to integrate data from several technologies (HPLC, GC-MS, microarrays) and using different data analysis methods (PCA, MFA). The results obtained increased our knowledge on the production of wine aroma and flavour, identifying new gene in association to the formation of flavour active compounds, mainly in the production of fatty acids, and ethyl and Acetate Esters.
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Key role of lipid management in nitrogen and aroma metabolism in an evolved wine yeast strain
Microbial Cell Factories, 2016Co-Authors: Stéphanie Rollero, Isabelle Sanchez, Carole Camarasa, Jean-roch Mouret, Anne Ortiz-julien, Jean-marie Sablayrolles, Sylvie DequinAbstract:Background: Fermentative aromas play a key role in the organoleptic profile of young wines. Their production depends both on yeast strain and fermentation conditions. A present-day trend in the wine industry consists in developing new strains with aromatic properties using adaptive evolution approaches. An evolved strain, Affinity T ECA5, overproducing Esters, was recently obtained. In this study, dynamics of nitrogen consumption and of the fermentative aroma synthesis of the evolved and its ancestral strains were compared and coupled with a transcriptomic analysis approach to better understand the metabolic reshaping of Affinity T ECA5. Results: Nitrogen assimilation was different between the two strains, particularly amino acids transported by carriers regulated by nitrogen catabolite repression. We also observed differences in the kinetics of fermentative aroma production, especially in the bioconversion of higher alcohols into Acetate Esters. Finally, transcriptomic data showed that the enhanced bioconversion into Acetate Esters by the evolved strain was associated with the repression of genes involved in sterol biosynthesis rather than an enhanced expression of ATF1 and ATF2 (genes coding for the enzymes responsible for the synthesis of Acetate Esters from higher alcohols). Conclusions: An integrated approach to yeast metabolism-combining transcriptomic analyses and online monitoring data-showed differences between the two strains at different levels. Differences in nitrogen source consumption were observed suggesting modifications of NCR in the evolved strain. Moreover, the evolved strain showed a different way of managing the lipid source, which notably affected the production of Acetate Esters, likely because of a greater availability of acetyl-CoA for the evolved strain.
Paul K. Boss - One of the best experts on this subject based on the ideXlab platform.
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Grape Contribution to Wine Aroma: Production of Hexyl Acetate, Octyl Acetate, and Benzyl Acetate during Yeast Fermentation Is Dependent upon Precursors in the Must
Journal of agricultural and food chemistry, 2012Co-Authors: Eric G. Dennis, Robert A. Keyzers, Curtis M. Kalua, Suzanne M. Maffei, Emily L. Nicholson, Paul K. BossAbstract:Wine is a complex consumer product produced predominately by the action of yeast upon grape juice musts. Model must systems have proven ideal for studies of the effects of fermentation conditions on the production of certain wine volatiles. To identify grape-derived precursors to Acetate Esters, model fermentation systems were developed by spiking precursors into model must at different concentrations. Solid-phase microextraction-gas chromatgraphy mass spectrometry analysis of the fermented wines showed that a variety of grape-derived aliphatic alcohols and aldehydes are precursors to Acetate Esters. The C6 compounds hexan-1-ol, hexenal, (E)-2-hexen-1-ol, and (E)-2-hexenal are all precursors to hexyl Acetate, and octanol and benzyl alcohol are precursors to octyl Acetate and benzyl Acetate, respectively. In these cases, the postfermentation concentration of an Acetate ester increased proportionally with the prefermentation concentration of the respective precursor in the model must. Determining viticultural or winemaking methods to alter the prefermentation concentration of precursor compounds or change the precursor-to-Acetate ester ratio will have implications upon the final flavor and aroma of wines.
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grape contribution to wine aroma production of hexyl Acetate octyl Acetate and benzyl Acetate during yeast fermentation is dependent upon precursors in the must
Journal of Agricultural and Food Chemistry, 2012Co-Authors: Eric G. Dennis, Robert A. Keyzers, Curtis M. Kalua, Suzanne M. Maffei, Emily L. Nicholson, Paul K. BossAbstract:Wine is a complex consumer product produced predominately by the action of yeast upon grape juice musts. Model must systems have proven ideal for studies of the effects of fermentation conditions on the production of certain wine volatiles. To identify grape-derived precursors to Acetate Esters, model fermentation systems were developed by spiking precursors into model must at different concentrations. Solid-phase microextraction–gas chromatgraphy mass spectrometry analysis of the fermented wines showed that a variety of grape-derived aliphatic alcohols and aldehydes are precursors to Acetate Esters. The C6 compounds hexan-1-ol, hexenal, (E)-2-hexen-1-ol, and (E)-2-hexenal are all precursors to hexyl Acetate, and octanol and benzyl alcohol are precursors to octyl Acetate and benzyl Acetate, respectively. In these cases, the postfermentation concentration of an Acetate ester increased proportionally with the prefermentation concentration of the respective precursor in the model must. Determining viticultur...
Sandeep Kumar - One of the best experts on this subject based on the ideXlab platform.
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supported palladium nanoparticles as switchable catalyst for aldehyde conjugate s and Acetate ester syntheses from alcohols
New Journal of Chemistry, 2017Co-Authors: Dhananjay Bhattacherjee, Vandna Thakur, Pralay Das, Sandeep Kumar, Abha ChaudharyAbstract:Polymer-supported Pd(0) (Pd@PS) nanoparticles (NPs) were explored as a switchable catalyst for oxidative aldehyde conjugate/s (AC/s) and Acetate Esters (AEs) syntheses from alcohols. Using the same substrates, the catalyst in the presence of oxygen and K2CO3 participated in AC/s synthesis, and in the presence of traces of air and NaOtBu, unusual AEs products were obtained.
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Supported palladium nanoparticles as switchable catalyst for aldehyde conjugate/s and Acetate ester syntheses from alcohols
New Journal of Chemistry, 2017Co-Authors: Sandeep Kumar, Dhananjay Bhattacherjee, Vandna Thakur, Abha Chaudhary, Bandna, Pralay DasAbstract:Polymer-supported Pd(0) (Pd@PS) nanoparticles (NPs) were explored as a switchable catalyst for oxidative aldehyde conjugate/s (AC/s) and Acetate Esters (AEs) syntheses from alcohols. Using the same substrates, the catalyst in the presence of oxygen and K2CO3 participated in AC/s synthesis, and in the presence of traces of air and NaOtBu, unusual AEs products were obtained.
