The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
Vicente Ferreira - One of the best experts on this subject based on the ideXlab platform.
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study of the influence of varietal amino acid profiles on the polyfunctional Mercaptans released from their precursors
Food Research International, 2017Co-Authors: Yohanna Alegre, Vicente Ferreira, Laura Cullere, Purificacion HernandezorteAbstract:Abstract Polyfunctional Mercaptans such as 4-mercapto-4-methyl-2-pentanone, 3-mercaptohexanol and 3-mercaptohexyl acetate contribute strongly to the varietal aroma of wines. These compounds are released during alcoholic fermentation from their precursors and their concentration is strongly linked to the grape variety. The aim of this work was to determine the effect of nine different amino acid profiles of grape varieties on the release of these polyfunctional Mercaptans and on the consumption of their precursors as well as to determine which are the preferred precursors. A set-up of fermentations of synthetic must was prepared, which simulated the amino acid profiles of nine different grape varieties, containing known amounts of polyfunctional mercaptan precursors as well as the elements necessary for the yeast metabolism. The yeast assimilable nitrogen was adjusted in percentage to reach 150 mg N/L in all the fermentations. Polyfunctional Mercaptans and their precursors were analyzed in the final wine by gas chromatography coupled to mass spectrometry with negative chemical ionization and ultrahigh liquid performance chromatography coupled to mass spectrometry, respectively. The results showed significant differences in the release of these polyfunctional Mercaptans as well as in the consumption of their precursors according to the amino acid profile. Moreover, it was observed that the preferred precursor of 4-mercapto-4-methyl-2-pentanone was its cysteinylated precursor. These results suggest that the amount of the amino acids as well as the ratio between them could modify the amount of polyfunctional Mercaptans released. This could be a tool for the wine industry to vary the aromatic profile of wines by increasing or decreasing these volatile thiols.
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Evolution of polyfunctional Mercaptans and their precursors during Merlot alcoholic fermentation
LWT - Food Science and Technology, 2016Co-Authors: Belen Concejero, Blanca Lacau, Jesús Astrain, Cristina Baron, Purificación Hernández-orte, Vicente FerreiraAbstract:Polyfunctional Mercaptans and their cysteinilated and glutathionilated precursors were analysed in samples taken at different densities during the alcoholic fermentation of five tanks in a two-year study. The aim was to determine when these compounds are extracted, released and degraded during this process. At the beginning of the fermentation, an increase in the concentration of cysteine-3-mercaptohexan-1-ol (CYSMH) and glutathione-3-mercaptohexan-1-ol (GLUMH) was observed, due to the extraction of these precursors from skin to must. Later on a decrease in the concentration was perceived as CYSMH and GLUMH broke up to release the polyfunctional Mercaptans and other non-identified compounds. The concentration of polyfunctional Mercaptans increased during alcoholic fermentation. There are significant differences in the concentration of all the volatile thiols and its precursors, between samples taken at different moments of the fermentation in each tank.However, even if a large concentration of CYS/GLU precursors in must was released, only a small concentration of polyfunctional Mercaptans liberated from them were found in wine. Probably, these compounds are labile and parts of them were degraded during the fermentation process.
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selective preconcentration of volatile Mercaptans in small spe cartridges quantitative determination of trace odor active polyfunctional Mercaptans in wine
IEEE Journal of Solid-state Circuits, 2009Co-Authors: Laura Mateovivaracho, Juan Cacho, Vicente FerreiraAbstract:A general procedure for the selective preconcentration and purification of Mercaptans has been developed. Mercaptans are strongly retained in a small (20 mg) SPE cartridge containing p-hydroxymercurybenzoate. The cartridge can then be rinsed with relatively high volumes of polar (water/methanol mixtures) and non-polar (pentane or pentane/ether mixtures) rinsing solutions to remove nearly all volatile compounds lacking a thiol functionality. Retained analytes are further eluted with a small volume of an organic solvent containing 1,4-dithioerythritol. Some basic aspects of the strategy, such as the retention of p-hydroxymercurybenzoate in the sorbent and its stability versus different rinsing and eluting systems, have been studied in depth. Light sulfur compounds contained in water or wine, including Mercaptans such as methanethiol or thioethers, such as diethyl sulfide, can be quantitatively extracted, although only Mercaptans can be quantitatively recovered if a polar rinsing is applied. The strategy has been applied to the GC-MS quantitative determination of some trace polyfunctional Mercaptans that are key aromas in wine, such as 2-methyl-3-furanthiol, 2-furfurylthiol, 4-mercapto-4-methyl-2-pentanone, 3-mercaptohexyl acetate or 3-mercaptohexanol. The developed method reaches detection limits in the ng/L range and has a satisfactory analytical behavior, being quite simple and fast.
Behnam Khoshandam - One of the best experts on this subject based on the ideXlab platform.
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Simulation and comparison of Sulfinol solvent performance with Amine solvents in removing sulfur compounds and acid gases from natural sour gas
Journal of Natural Gas Science and Engineering, 2015Co-Authors: Hassan Ghanbarabadi, Behnam KhoshandamAbstract:Natural gas issued from well production has to be treated to remove acid gases (CO2 and H2S) and sulfur compounds so that it meets transport requirements and sale gas specifications. Two great families of solvents are used for this kind of gas treatment: chemical and physical solvents. Ilam gas refinery (one of the main gas refineries in Iran) discharges high levels of Mercaptans in the production of raw LPG and condensates, and also there are problems with sulfur compounds because of the lack of Merox unit. In this research, we carry out the simulation and study of removing acid gases (CO2, H2S) and sulfur compounds (methyl and ethyl Mercaptans, dimethyl-sulfide, COS) with mixed solvent Sulfinol (Sulfolane+MDEA+H2O) and DGA, MDEA+AMP solvents and compare it with the present solvent MDEA. The purpose of this research is the feasibility study of utilizing Sulfinol-M solvent to replace the aqueous amine solvent in the gas sweetening unit of Ilam gas refinery. The results of the simulation show that more than 30-40% of Mercaptans along with sour gas is absorbed with Sulfinol-M solvent of lower flow rate and a considerable 10-25% less energy is required for solvent regeneration; furthermore, very little waste of solvent is observed compared with amine solvents (MDEA+AMP, DGA, MDEA). Many of the process parameters are controlled more easily than amine solvents with the characteristic of the composition of Sulfinol-M compound and there will be energy and economic saving in different sections of mercaptan and acid gas absorption.
Carlos Wexler - One of the best experts on this subject based on the ideXlab platform.
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On the reversibility of the adsorption of methane-methyl mercaptan mixtures in nanoporous carbon.
Carbon, 2012Co-Authors: Monika Golebiowska, Lucyna Firlej, M.w. Roth, Bogdan Kuchta, Carlos WexlerAbstract:The results of extensive molecular dynamics simulations and theoretical considerations of the adsorption of methane-methyl mercaptan mixtures in slit-shaped carbon nanopores are presented. We observe significant mobility of both methane and mercaptan molecules within the pore volume, between pores, and between adsorbed and gas phases for a wide range of temperatures and pressures. Although Mercaptans adsorb preferentially relative to methane, the process remains reversible, provided non-oxidizing conditions are maintained. A mercaptan/methane ratio of the order of 200 ppm in the adsorbed phase is sufficient for the gas phase to have a mercaptan concentration above the human threshold for detection. The reversibility of the adsorption process and low concentration of Mercaptans makes it unlikely that these would be harmful for adsorbed natural gas storage systems.
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On the reversibility of the adsorption methan-mercaptan for natural gas storage
2011Co-Authors: Monika Golebiowska, Lucyna Firlej, M.w. Roth, Bogdan Kuchta, Carlos WexlerAbstract:ethane is the main constituent of natural gas (NG). As fuel for vehicular appli- cations NG requires sorbents that allow e±cient, reversible and safe storage at room temperature and moderate pressure. To enable easy human detection of gas leaks the fuel gas should be added with compounds having low odor threshold, such as thi- ols (Mercaptans). Thus a full understanding of the behavior of methane-mercaptan mixtures is necessary for the development of safe storage systems. In this talk we present results of molecular dynamics simulations in the temperature range 150{350 K and for a large range of methane partial pressures, up to the saturation pressure of methane. We observe the presence of 2D (and to a lesser degree 3D) diÆusion of the thiols indicating that though thiols adsorb preferentially relative to methane, the adsorption is still reversible. We estimate that only a small increase in mercaptan concentration is necessary for the desorbed phase to be above the threshold for human detection.
Hassan Ghanbarabadi - One of the best experts on this subject based on the ideXlab platform.
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Simulation and comparison of Sulfinol solvent performance with Amine solvents in removing sulfur compounds and acid gases from natural sour gas
Journal of Natural Gas Science and Engineering, 2015Co-Authors: Hassan Ghanbarabadi, Behnam KhoshandamAbstract:Natural gas issued from well production has to be treated to remove acid gases (CO2 and H2S) and sulfur compounds so that it meets transport requirements and sale gas specifications. Two great families of solvents are used for this kind of gas treatment: chemical and physical solvents. Ilam gas refinery (one of the main gas refineries in Iran) discharges high levels of Mercaptans in the production of raw LPG and condensates, and also there are problems with sulfur compounds because of the lack of Merox unit. In this research, we carry out the simulation and study of removing acid gases (CO2, H2S) and sulfur compounds (methyl and ethyl Mercaptans, dimethyl-sulfide, COS) with mixed solvent Sulfinol (Sulfolane+MDEA+H2O) and DGA, MDEA+AMP solvents and compare it with the present solvent MDEA. The purpose of this research is the feasibility study of utilizing Sulfinol-M solvent to replace the aqueous amine solvent in the gas sweetening unit of Ilam gas refinery. The results of the simulation show that more than 30-40% of Mercaptans along with sour gas is absorbed with Sulfinol-M solvent of lower flow rate and a considerable 10-25% less energy is required for solvent regeneration; furthermore, very little waste of solvent is observed compared with amine solvents (MDEA+AMP, DGA, MDEA). Many of the process parameters are controlled more easily than amine solvents with the characteristic of the composition of Sulfinol-M compound and there will be energy and economic saving in different sections of mercaptan and acid gas absorption.
Monika Golebiowska - One of the best experts on this subject based on the ideXlab platform.
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On the reversibility of the adsorption of methane-methyl mercaptan mixtures in nanoporous carbon.
Carbon, 2012Co-Authors: Monika Golebiowska, Lucyna Firlej, M.w. Roth, Bogdan Kuchta, Carlos WexlerAbstract:The results of extensive molecular dynamics simulations and theoretical considerations of the adsorption of methane-methyl mercaptan mixtures in slit-shaped carbon nanopores are presented. We observe significant mobility of both methane and mercaptan molecules within the pore volume, between pores, and between adsorbed and gas phases for a wide range of temperatures and pressures. Although Mercaptans adsorb preferentially relative to methane, the process remains reversible, provided non-oxidizing conditions are maintained. A mercaptan/methane ratio of the order of 200 ppm in the adsorbed phase is sufficient for the gas phase to have a mercaptan concentration above the human threshold for detection. The reversibility of the adsorption process and low concentration of Mercaptans makes it unlikely that these would be harmful for adsorbed natural gas storage systems.
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On the reversibility of the adsorption methan-mercaptan for natural gas storage
2011Co-Authors: Monika Golebiowska, Lucyna Firlej, M.w. Roth, Bogdan Kuchta, Carlos WexlerAbstract:ethane is the main constituent of natural gas (NG). As fuel for vehicular appli- cations NG requires sorbents that allow e±cient, reversible and safe storage at room temperature and moderate pressure. To enable easy human detection of gas leaks the fuel gas should be added with compounds having low odor threshold, such as thi- ols (Mercaptans). Thus a full understanding of the behavior of methane-mercaptan mixtures is necessary for the development of safe storage systems. In this talk we present results of molecular dynamics simulations in the temperature range 150{350 K and for a large range of methane partial pressures, up to the saturation pressure of methane. We observe the presence of 2D (and to a lesser degree 3D) diÆusion of the thiols indicating that though thiols adsorb preferentially relative to methane, the adsorption is still reversible. We estimate that only a small increase in mercaptan concentration is necessary for the desorbed phase to be above the threshold for human detection.