The Experts below are selected from a list of 963 Experts worldwide ranked by ideXlab platform

Yorgos Kotseridis - One of the best experts on this subject based on the ideXlab platform.

  • Methoxypyrazine Analysis and Influence of Viticultural and Enological Procedures on their Levels in Grapes, Musts, and Wines
    Critical reviews in food science and nutrition, 2014
    Co-Authors: Davinder Sidhu, Yorgos Kotseridis, Jensen A. Lund, Cédric Saucier
    Abstract:

    This review discusses the factors that affect the concentrations of Methoxypyrazines (MPs) and the techniques used to analyze MPs in grapes, musts, and wines. MPs are commonly studied pyrazines in food science due to their contribution of aroma and flavor to numerous vegetables such as peas and asparagus. They are described as highly odorous compounds with a very low olfactory threshold. The grape varietals that exhibit green or herbaceous aromas that are characteristic of MPs are predominantly Vitis vinifera cv. Cabernet Sauvignon and Sauvignon Blanc, but include others. The most extensively studied MPs include 3-isobutyl-2-methoxypyrazine, 3-isopropyl-2-methoxypyrazine, and 3-sec-butyl-2-methoxypyrazine. It outlines the significance of Methoxypyrazines in grapes, musts, and wines in terms of the concentrations that are capable of contributing their sensory characteristics to wines. This review discusses methods for analyzing MPs including gas chromatography-mass spectroscopy (one or two dimension) and high-performance liquid chromatography, the appropriate extraction techniques, and the efficacy of these methods. Additionally, this review explores factors that affect pyrazine content of grapes, must, and wines, such as the effects of different viticultural practices, effects of light exposure and grape maturation, climate, soil, the multi-colored Asian lady beetle and the effects of different vinification processes.

  • Development of a rapid method for the quantitative analysis of four Methoxypyrazines in white and red wine using multi-dimensional Gas Chromatography-Mass Spectrometry.
    Food chemistry, 2014
    Co-Authors: Andreea Botezatu, Gary J. Pickering, Yorgos Kotseridis
    Abstract:

    Alkyl-Methoxypyrazines (MPs) are important odour-active constituents of many grape cultivars and their wines. Recently, a new MP - 2,5-dimethyl-3-methoxypyrazine (DMMP) - has been reported as a possible constituent of wine. This study sought to develop a rapid and reliable method for quantifying DMMP, isopropyl methoxypyrazine (IPMP), secbutyl methoxypyrazine (SBMP) and isobutyl methoxypyrazine (IBMP) in wine. The proposed method is able to rapidly and accurately resolve all 4 MPs in a range of wine styles, with limits of detection between 1 and 2 ng L(-1) for IPMP, SBMP and IBMP and 5 ng L(-1) for DMMP. Analysis of a set of 11 commercial wines agrees with previously published values for IPMP, SBMP and IBMP, and shows for the first time that DMMP may be an important and somewhat common odorant in red wines. To our knowledge, this is the first analytical method developed for the quantification of DMMP in wine.

  • Occurrence and contribution of alkyl Methoxypyrazines in wine tainted by Harmonia axyridis and Coccinella septempunctata
    Journal of the Science of Food and Agriculture, 2012
    Co-Authors: Andreea Botezatu, Yorgos Kotseridis, Debbie Inglis, Gary J. Pickering
    Abstract:

    BACKGROUND: Ladybug taint (LBT) is a wine fault caused by the inadvertent incorporation of ladybeetles to the wine during the winemaking process. Harmonia axyridis, also known as the multicolored Asian lady-beetle (MALB), was the only species considered responsible for causing the taint. A second species, Coccinella septempunctata (7 Spot), has recently also been implicated. The main objectives of this study were to identify and quantify the compounds associated with ladybug taint of white and red wine from these two Coccinellidae species (Harmonia axyridis and Coccinella septempunctata), and determine the most odor-active compounds in LBT-affected wines. RESULTS: Results show that Coccinellidae can contribute dimethyl, isopropyl, secbutyl and isobutyl methoxypyrazine to wine when they are processed with grapes, and that the methoxypyrazine composition varies between MALB and 7 Spot. Isopropyl methoxypyrazine is the major contributor to LBT in wines produced with these ladybeetle species, although secbutyl and isobutyl methoxypyrazine may contribute in MALB- and 7 Spot-affected wines, respectively. Finally, dimethyl methoxypyrazine is reported for the first time in wines not affected by Coccinellidae; the global significance and prevalence of this compound in wine remains to be determined. CONCLUSION: Both Harmonia axyridis and Coccinella septempunctata can contribute alkyl Methoxypyrazines, and particularly isopropyl methoxypyrazine, to wine at concentrations that can have a negative impact on wine quality. These findings will allow grape growers and winemakers to be more aware of the risks posed by 7 Spot beetles, and to take the appropriate preventative and remedial actions. Furthermore, this is the first time dimethyl methoxypyrazine is reported in wine, either as an endogenous or Coccinellidae-derived odorant. © 2012 Society of Chemical Industry

  • Occurrence and contribution of alkyl Methoxypyrazines in wine tainted by Harmonia axyridis and Coccinella septempunctata
    Journal of the science of food and agriculture, 2012
    Co-Authors: Andreea Botezatu, Yorgos Kotseridis, Debbie Inglis, Gary J. Pickering
    Abstract:

    Ladybug taint (LBT) is a wine fault caused by the inadvertent incorporation of ladybeetles to the wine during the winemaking process. Harmonia axyridis, also known as the multicolored Asian lady-beetle (MALB), was the only species considered responsible for causing the taint. A second species, Coccinella septempunctata (7 Spot), has recently also been implicated. The main objectives of this study were to identify and quantify the compounds associated with ladybug taint of white and red wine from these two Coccinellidae species (Harmonia axyridis and Coccinella septempunctata), and determine the most odor-active compounds in LBT-affected wines. Results show that Coccinellidae can contribute dimethyl, isopropyl, secbutyl and isobutyl methoxypyrazine to wine when they are processed with grapes, and that the methoxypyrazine composition varies between MALB and 7 Spot. Isopropyl methoxypyrazine is the major contributor to LBT in wines produced with these ladybeetle species, although secbutyl and isobutyl methoxypyrazine may contribute in MALB- and 7 Spot-affected wines, respectively. Finally, dimethyl methoxypyrazine is reported for the first time in wines not affected by Coccinellidae; the global significance and prevalence of this compound in wine remains to be determined. Both Harmonia axyridis and Coccinella septempunctata can contribute alkyl Methoxypyrazines, and particularly isopropyl methoxypyrazine, to wine at concentrations that can have a negative impact on wine quality. These findings will allow grape growers and winemakers to be more aware of the risks posed by 7 Spot beetles, and to take the appropriate preventative and remedial actions. Furthermore, this is the first time dimethyl methoxypyrazine is reported in wine, either as an endogenous or Coccinellidae-derived odorant. © 2012 Society of Chemical Industry.

  • Effect of light and temperature on 3-alkyl-2-methoxypyrazine concentration and other impact odourants of Riesling and Cabernet Franc wine during bottle ageing
    Food Chemistry, 2010
    Co-Authors: A Blake, Ian D. Brindle, Yorgos Kotseridis, Debra L. Inglis, Gary J. Pickering
    Abstract:

    Abstract 3-Alkyl-2-Methoxypyrazines (MPs) are grape- and insect-derived odour-active compounds responsible for green and vegetative perceptions in wine, and at elevated concentrations are detrimental to wine quality. We examined the influence of light and temperature during cellaring on MPs and other impact odourants. Riesling and Cabernet Franc wines were supplemented with 30 ng/L of each of 3-isopropyl-2-methoxypyrazine (IPMP), 3-s-butyl-2-methoxypyrazine (SBMP) and 3-isobutyl-2-methoxypyrazine (IBMP), and stored under one of the following conditions: (i) at ambient temperature (22 °C) under fluorescent lighting, (ii) in the dark at ambient temperature, or (iii) in the dark at cellar temperature (12 °C). Additionally, for the light condition, wine was stored in clear, green or amber bottles. MPs did not vary consistently over time under any of these light or temperature conditions. IBMP decreased over 12 month by approx. 30% under all conditions in both Riesling and Cabernet Franc. Acetate esters also decreased with time, regardless of light or temperature conditions, while phenethyl acetate and isoamyl acetate decreased at a greater rate at 22 °C compared with 12 °C. Free and bound SO 2 retention was higher in light-excluded conditions and influenced by bottle hue. Measures of browning and phenolic content were also affected to varying degrees by bottle hue and storage temperature. These results should assist winemakers in selecting bottle hues, and assist in selection of optimum storage conditions for preserving wine quality in both retail and cellar environments.

Hans-georg Schmarr - One of the best experts on this subject based on the ideXlab platform.

  • quantification of cork off flavor compounds in natural cork stoppers and wine by multidimensional gas chromatography mass spectrometry
    European Food Research and Technology, 2016
    Co-Authors: Petra Slabizki, Claus Fischer, Charlotte Legrum, Pascal Wegmannherr, Hans-georg Schmarr
    Abstract:

    Trace-level analysis of cork off-flavor compounds considered as responsible for typical [2,4,6-trichloroanisole (TCA)] and atypical cork taint [geosmin (GSM); 2-methylisoborneol (MIB); 3-isopropyl-2-methoxypyrazine (IPMP); 3-isobutyl-2-methoxypyrazine (IBMP); 3,5-dimethyl-2-methoxypyrazine (MDMP)] was achieved for cork soaks and wines for concentrations below odor threshold (MIB only in cork soaks). The analytical approach was based on headspace solid-phase microextraction and heart-cut multidimensional gas chromatography with tandem mass spectrometric detection. Quantification was done using a stable isotope dilution assay. Individual cork stoppers with varying sensory off-odor descriptions were analyzed. In particular, IPMP and IBMP correlated with the cork stoppers described with green attributes. MDMP was found in samples described as dusty–musty or nutty-like. In a migration study, transport of off-flavor compounds from affected cork stoppers into the corresponding wine could be observed after a storage period of 13 months. Multivariate statistics on the wines’ sensory analysis and chemical data showed a good correlation of the individual off-flavor compound concentration, its sensory description and the off-flavor perceived in the wine.

  • characterization of atypical off flavor compounds in natural cork stoppers by multidimensional gas chromatographic techniques
    Journal of Agricultural and Food Chemistry, 2015
    Co-Authors: Petra Slabizki, Claus Fischer, Charlotte Legrum, Hans-georg Schmarr
    Abstract:

    Natural cork stoppers with sensory deviations other than the typical cork taint were subgrouped according to their sensory descriptions and compared with unaffected control cork stoppers. The assessment of purge and trap extracts obtained from corresponding cork soaks was performed by heart-cut multidimensional gas chromatography–olfactometry (MDGC-O). The identification of compounds responsible for atypical cork taint detected in MDGC-O was further supported with additional multidimensional GC analysis in combination with mass spectrometric detection. Geosmin and 2-methylisoborneol were mainly found in cork stoppers described as moldy and cellarlike; 3-isopropyl-2-methoxypyrazine and 3-isobutyl-2-methoxypyrazine were found in cork stoppers described with green attributes. Across all cork subgroups, the impact compound for typical cork taint, 2,4,6-trichloroanisole (TCA), was present and is therefore a good marker for cork taint in general. Another potent aroma compound, 3,5-dimethyl-2-methoxypyrazine (MD...

  • Enantiodifferentiation of 3- sec -butyl-2-methoxypyrazine in different species using multidimensional and comprehensive two-dimensional gas chromatographic approaches
    Analytical and bioanalytical chemistry, 2014
    Co-Authors: Charlotte Legrum, Petra Slabizki, Hans-georg Schmarr
    Abstract:

    With respect to the current hypothesis that natural amino acids may serve as starting material for the biosynthesis of alkyl-Methoxypyrazines, the enantiomeric distribution of the potent aroma compound 3-sec-butyl-2-methoxypyrazine (SBMP) was determined in various species using heart-cut multidimensional gas chromatography (H/C MDGC) or comprehensive two-dimensional gas chromatography (GC × GC). Complementary to an earlier described separation on octakis-(6-O-methyl-2,3-di-O-pentyl)-γ-cyclodextrin used as chiral stationary phase, we found a reversal of the elution order of SBMP enantiomers on heptakis-(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-β-cyclodextrin, providing further confirmation options for that type of analysis. Optimization of the enantioseparation of SBMP in a single-oven H/C enantio-MDGC system involved the use of a dual-jet cryo modulator for trapping of analytes transferred from the achiral (1)D column to the chiral (2)D column before starting the (2)D enantioseparation with an independent temperature ramp. For the enantiodifferentiation by enantio-GC × GC, the modulation period had to be significantly shortened to avoid loss of chiral resolution gained in (1)D. H/C MDGC with mass spectrometric detection (MS) using selected ion monitoring (SIM) was sufficient for parts per billion level analysis, whereas H/C MDGC-MS/MS or GC × GC time-of-flight (TOF) MS were necessary for parts per trillion level analysis. In various vegetables, lady beetles and Vitis vinifera species analyzed, only (S)-SBMP was detected, supporting the hypothesis of natural amino acids serving as starting material for the biosynthesis of alkyl-Methoxypyrazines.

  • characterization and analysis of structural isomers of dimethyl Methoxypyrazines in cork stoppers and ladybugs harmonia axyridis and coccinella septempunctata
    Analytical and Bioanalytical Chemistry, 2014
    Co-Authors: Petra Slabizki, Charlotte Legrum, Reinhard Meusinger, Hans-georg Schmarr
    Abstract:

    The three constitutional isomers of dimethyl-substituted Methoxypyrazines: 3,5-dimethyl-2-methoxypyrazine 1; 2,5-dimethyl-3-methoxypyrazine 2; and 2,3-dimethyl-5-methoxypyrazine 3 are potent flavor compounds with similar mass spectrometric, gas chromatographic, and nuclear magnetic resonance spectroscopic behavior. Therefore, unambiguous analytical determination is critical, particularly in complex matrices. The unequivocal identification of 1–3 could be achieved by homo- and heteronuclear NMR correlation experiments. The observed mass fragmentation for 1–3 is proposed and discussed, benefitting from synthesized partially deuterated 1 and 2. On common polar and apolar stationary phases used in gas chromatography (GC) 1 and 2 show similar behavior whereas 3 can be separated. In our focus on off-flavor analysis with respect to wine aroma, 1 has been described as a “moldy” off-flavor compound in cork and 2 as a constituent in Harmonia axyridis contributing to the so-called “ladybug taint,” whereas 3 has not yet been described as a constituent of wine aroma. A successful separation of 1 and 2 could be achieved on octakis-(2,3-di-O-pentyl-6-O-methyl)-γ-cyclodextrin as stationary phase in GC. Applying heart-cut multidimensional GC analysis with tandem mass spectrometric detection we could confirm the presence of 1 as a “moldy” off-flavor compound in cork. However, in the case of Harmonia axyridis, a previous identification of 2 has to be reconsidered. In our experiments we identified the constitutional isomer 1, which was also found in Coccinella septempunctata, another species discussed with respect to the “ladybug taint.” The analysis of such structurally related compounds is a demonstrative example for the importance of a chromatographic separation, as mass spectrometric data by itself could not guarantee the unequivocal identification.

  • Pitfalls encountered during quantitative determination of 3-alkyl-2-Methoxypyrazines in grape must and wine using gas chromatography-mass spectrometry with stable isotope dilution analysis. Comprehensive two-dimensional gas chromatography-mass spectr
    Journal of chromatography. A, 2010
    Co-Authors: Hans-georg Schmarr, Sebastian Ganss, Stefan Koschinski, Ulrich Fischer, Carmen Riehle, Julian Kinnart, Theodoros Potouridis, Maria Kutyrev
    Abstract:

    The analysis of 3-alkyl-2-Methoxypyrazines in Vitis vinifera grape must or wine at the low nanogram per liter level failed in several situations when applying a one-dimensional gas chromatographic analysis with mass spectrometric detection (GC-MS). Sample preparation methods such as headspace solid phase microextraction or solid phase extraction were convenient procedures, however lacking extraction selectivity for complex matrices. Analysis by comprehensive two-dimensional gas chromatography with mass spectrometric detection clearly demonstrated the potential for co-elution in such matrices and the risk for erroneous results when applying one-dimensional GC-MS. In one example, matrix problems would have been a challenge even for a comprehensive two-dimensional chromatographic approach with MS detection (GC×GC-MS). A solution to matrix problems was found by protonating the 3-alkyl-2-Methoxypyrazines in acidic pH and sample clean-up using solid phase extraction with a mixed-mode polymeric cation-exchange sorbent. Quantification was performed by a stable isotope dilution assay, following analysis by on-line coupled high performance liquid chromatography with multidimensional gas chromatography and detection with mass spectrometry (on-line LC-MDGC-MS). This new approach allowed trace-level analysis of 3-alkyl-2-Methoxypyrazines in grape musts and wines and is described for V. vinifera Sauvignon blanc, following 3-alkyl-2-Methoxypyrazines concentrations during ripening and in the processed wines.

Gary J. Pickering - One of the best experts on this subject based on the ideXlab platform.

  • Application of plastic polymers in remediating wine with elevated alkyl-methoxypyrazine levels
    Food additives & contaminants. Part A Chemistry analysis control exposure & risk assessment, 2015
    Co-Authors: Andreea Botezatu, Gary J. Pickering
    Abstract:

    3-Alkyl-2-Methoxypyrazines (MPs) are odour-active compounds that elicit atypical green aromas and flavours in some wines, and are resilient to removal using traditional wine-making approaches. They originate either as contaminants from Coccinellidae beetles inadvertently introduced during wine processing ("ladybug taint") or as grape-derived constituents that are undesirable at elevated levels. In this study we investigated the capacity of a selection of plastic polymers to reduce concentrations of three MPs: isopropyl methoxypyrazine (IPMP), secbutyl methoxypyrazine (SBMP) and isobutyl methoxypyrazine (IBMP). In Trial 1, red wine was spiked with IPMP (20 ng/l), SBMP (20 ng/l) and IBMP (20 ng/l), then separately treated with 13 plastic polymers (surface area 350 cm(2)/l). Three polymers were then identified for further testing based on the results from Trial 1: silicone, ethylene and vinyl acetate (EVA) and a poly-lactic acid-based biodegradable polymer. In Trial 2, the efficacy of these selected polymers to reduce MP levels in red wine was tested as a function of contact time. Solid-phase micro-extraction multi-dimensional GC-MS was used to measure MP levels before and after treatment with the polymers. Results showed significant reductions in all target odorants after 24 h treatment: silicone reduced IPMP and IBMP by 96% and 100%, respectively, while the biodegradable polymer decreased IPMP and IBMP concentrations by 52% and 36%, respectively. EVA was less effective in lowering MP levels (7% IPMP and 23% IBMP after 24 h). Taken overall, the data suggest the potential for the use of poly-lactic acid and silicone in treating wines contaminated by ladybug taint, as well as in reducing high levels of grape-derived MPs.

  • Novel Applications for Biomaterials: The Case of Remediation of Wine Taints Using Poly-lactic Acid Polymer
    Applied Mechanics and Materials, 2015
    Co-Authors: Andreea Botezatu, Gary J. Pickering
    Abstract:

    Wine is the world’s oldest alcoholic beverage and the most consumed in at least 20 countries. However, taints detract from its quality and acceptance, significantly reducing the value of wine. In this study we investigated the capacity of a poly-lactic acid (PLA) biopolymer to reduce concentrations of four odorants responsible for tainting many red wines: isopropyl-methoxypyrazine (IPMP), isobutyl–methoxypyrazine (IBMP), 4-ethylphenol (4-EP) and 4-ethylguaiacol (4-EG). Red wine was spiked with either IPMP [20 ng/L] and IBMP [20 ng/L] (Study 1) or 4-EP [200 ug/L] and 4-EG [200 ug/L] (Study 2) and then treated with a PLA film [surface area 350 cm2/L]. Solid Phase Micro-Extraction Multi-Dimensional Gas Chromatography–Mass Spectrometry and Gas Chromatography-Mass Spectrometry were used to measure the Methoxypyrazines and ethylphenols, respectively, both before and after treatment with PLA. Results showed significant reductions in all of the target odorants after 8hrs treatment: IPMP (51%), IBMP (26%), 4-EP (21%) and 4-EG (20%). Taken overall, the data suggest potential for the use of PLA in treating common wine faults, particularly ‘ladybug taint’, which is caused by elevated levels of IPMP.

  • Methoxypyrazine composition of Coccinellidae-tainted Riesling and Pinot noir wine from Germany
    Journal of the science of food and agriculture, 2014
    Co-Authors: Susanne Kögel, Andreea Botezatu, Christoph Hoffmann, Gary J. Pickering
    Abstract:

    Harmonia axyridis (multicolored Asian ladybeetle) and Coccinella septempunctata (seven-spot ladybeetle) (Coccinellidae) are found in many wine regions in Europe and the Americas, where they are responsible for a pronounced wine fault known as 'ladybug taint' when incorporated with grapes during harvest operations. Methoxypyrazines have been proposed in the literature as the compounds responsible for the taint. This study sought to expand on this identification and also determine the effectiveness of heating Coccinellidae-affected grape must prior to fermentation as a possible remedial intervention. Riesling and Pinot noir grapes were infested with H. axyridis or C. septempunctata at different densities and fermented to dryness. The Pinot noir was either must heated prior to fermentation or processed without heating (control). All wines were analyzed for 2-isopropyl-, 2-sec-butyl-, 2-isobutyl- and 2,5-dimethyl-3-methoxypyrazine using headspace solid phase microextraction/multidimensional gas chromatography/mass spectrometry. Concentrations of 2-isopropyl-3-methoxypyrazine increased with beetle density for both Coccinellidae species, while other Methoxypyrazines showed inconsistent or no variation with infestations levels. Heating of Pinot noir grapes prior to fermentation resulted in a moderate decrease in all Methoxypyrazines. These results provide direction for more targeted treatments aimed at remediating musts/wines affected by Coccinellidae and indicate that winegrowers do not need to differentiate between H. axyridis and C. septempunctata when making action threshold decisions in the vineyard or winery. © 2014 Society of Chemical Industry.

  • Development of a rapid method for the quantitative analysis of four Methoxypyrazines in white and red wine using multi-dimensional Gas Chromatography-Mass Spectrometry.
    Food chemistry, 2014
    Co-Authors: Andreea Botezatu, Gary J. Pickering, Yorgos Kotseridis
    Abstract:

    Alkyl-Methoxypyrazines (MPs) are important odour-active constituents of many grape cultivars and their wines. Recently, a new MP - 2,5-dimethyl-3-methoxypyrazine (DMMP) - has been reported as a possible constituent of wine. This study sought to develop a rapid and reliable method for quantifying DMMP, isopropyl methoxypyrazine (IPMP), secbutyl methoxypyrazine (SBMP) and isobutyl methoxypyrazine (IBMP) in wine. The proposed method is able to rapidly and accurately resolve all 4 MPs in a range of wine styles, with limits of detection between 1 and 2 ng L(-1) for IPMP, SBMP and IBMP and 5 ng L(-1) for DMMP. Analysis of a set of 11 commercial wines agrees with previously published values for IPMP, SBMP and IBMP, and shows for the first time that DMMP may be an important and somewhat common odorant in red wines. To our knowledge, this is the first analytical method developed for the quantification of DMMP in wine.

  • Occurrence and contribution of alkyl Methoxypyrazines in wine tainted by Harmonia axyridis and Coccinella septempunctata
    Journal of the Science of Food and Agriculture, 2012
    Co-Authors: Andreea Botezatu, Yorgos Kotseridis, Debbie Inglis, Gary J. Pickering
    Abstract:

    BACKGROUND: Ladybug taint (LBT) is a wine fault caused by the inadvertent incorporation of ladybeetles to the wine during the winemaking process. Harmonia axyridis, also known as the multicolored Asian lady-beetle (MALB), was the only species considered responsible for causing the taint. A second species, Coccinella septempunctata (7 Spot), has recently also been implicated. The main objectives of this study were to identify and quantify the compounds associated with ladybug taint of white and red wine from these two Coccinellidae species (Harmonia axyridis and Coccinella septempunctata), and determine the most odor-active compounds in LBT-affected wines. RESULTS: Results show that Coccinellidae can contribute dimethyl, isopropyl, secbutyl and isobutyl methoxypyrazine to wine when they are processed with grapes, and that the methoxypyrazine composition varies between MALB and 7 Spot. Isopropyl methoxypyrazine is the major contributor to LBT in wines produced with these ladybeetle species, although secbutyl and isobutyl methoxypyrazine may contribute in MALB- and 7 Spot-affected wines, respectively. Finally, dimethyl methoxypyrazine is reported for the first time in wines not affected by Coccinellidae; the global significance and prevalence of this compound in wine remains to be determined. CONCLUSION: Both Harmonia axyridis and Coccinella septempunctata can contribute alkyl Methoxypyrazines, and particularly isopropyl methoxypyrazine, to wine at concentrations that can have a negative impact on wine quality. These findings will allow grape growers and winemakers to be more aware of the risks posed by 7 Spot beetles, and to take the appropriate preventative and remedial actions. Furthermore, this is the first time dimethyl methoxypyrazine is reported in wine, either as an endogenous or Coccinellidae-derived odorant. © 2012 Society of Chemical Industry

Ian D. Brindle - One of the best experts on this subject based on the ideXlab platform.

  • Effect of light and temperature on 3-alkyl-2-methoxypyrazine concentration and other impact odourants of Riesling and Cabernet Franc wine during bottle ageing
    Food Chemistry, 2010
    Co-Authors: A Blake, Ian D. Brindle, Yorgos Kotseridis, Debra L. Inglis, Gary J. Pickering
    Abstract:

    Abstract 3-Alkyl-2-Methoxypyrazines (MPs) are grape- and insect-derived odour-active compounds responsible for green and vegetative perceptions in wine, and at elevated concentrations are detrimental to wine quality. We examined the influence of light and temperature during cellaring on MPs and other impact odourants. Riesling and Cabernet Franc wines were supplemented with 30 ng/L of each of 3-isopropyl-2-methoxypyrazine (IPMP), 3-s-butyl-2-methoxypyrazine (SBMP) and 3-isobutyl-2-methoxypyrazine (IBMP), and stored under one of the following conditions: (i) at ambient temperature (22 °C) under fluorescent lighting, (ii) in the dark at ambient temperature, or (iii) in the dark at cellar temperature (12 °C). Additionally, for the light condition, wine was stored in clear, green or amber bottles. MPs did not vary consistently over time under any of these light or temperature conditions. IBMP decreased over 12 month by approx. 30% under all conditions in both Riesling and Cabernet Franc. Acetate esters also decreased with time, regardless of light or temperature conditions, while phenethyl acetate and isoamyl acetate decreased at a greater rate at 22 °C compared with 12 °C. Free and bound SO 2 retention was higher in light-excluded conditions and influenced by bottle hue. Measures of browning and phenolic content were also affected to varying degrees by bottle hue and storage temperature. These results should assist winemakers in selecting bottle hues, and assist in selection of optimum storage conditions for preserving wine quality in both retail and cellar environments.

  • Effect of closure and packaging type on 3-alkyl-2-Methoxypyrazines and other impact odorants of Riesling and Cabernet Franc wines.
    Journal of agricultural and food chemistry, 2009
    Co-Authors: A Blake, Yorgos Kotseridis, Debbie Inglis, Ian D. Brindle, Mark K Sears, Gary J. Pickering
    Abstract:

    3-Alkyl-2-Methoxypyrazines (MPs) represent an important and potent class of grape- and insect-derived odor-active compounds associated with wine quality. Thirty nanograms per liter each of 3-isobutyl-2-methoxypyrazine (IBMP), 3-isopropyl-2-methoxypyrazine (IPMP), and 3-sec-butyl-2-methoxypyrazine (SBMP) was added to Riesling and Cabernet Franc wines and monitored with headspace solid-phase microextraction and gas chromatography-mass spectrometry over 18 months to investigate the effects of various closure and packaging options on MPs. Changes in MP concentrations during bottle aging varied with closure/packaging option, with the greatest decrease evident in Tetrapak cartons. After 18 months, IBMP, IPMP, and SBMP in both Tetrapak-stored wines decreased by approximately 45, 32, and 26%, respectively. Similar changes were observed in other impact odorants to previous studies, including a greater decrease in odorant concentrations in wines closed with synthetic corks compared to natural corks and screw caps. These differences are thought to be due to the differential sorptive capacities of the various closure types. Overall, the data suggest that differences in gas permeability/contribution from the different closure and packaging options strongly associate with changes in wine composition during aging.

  • effect of closure and packaging type on 3 alkyl 2 Methoxypyrazines and other impact odorants of riesling and cabernet franc wines
    Journal of Agricultural and Food Chemistry, 2009
    Co-Authors: A Blake, Yorgos Kotseridis, Debbie Inglis, Ian D. Brindle, Mark K Sears, Gary J. Pickering
    Abstract:

    3-Alkyl-2-Methoxypyrazines (MPs) represent an important and potent class of grape- and insect-derived odor-active compounds associated with wine quality. Thirty nanograms per liter each of 3-isobutyl-2-methoxypyrazine (IBMP), 3-isopropyl-2-methoxypyrazine (IPMP), and 3-sec-butyl-2-methoxypyrazine (SBMP) was added to Riesling and Cabernet Franc wines and monitored with headspace solid-phase microextraction and gas chromatography−mass spectrometry over 18 months to investigate the effects of various closure and packaging options on MPs. Changes in MP concentrations during bottle aging varied with closure/packaging option, with the greatest decrease evident in Tetrapak cartons. After 18 months, IBMP, IPMP, and SBMP in both Tetrapak-stored wines decreased by approximately 45, 32, and 26%, respectively. Similar changes were observed in other impact odorants to previous studies, including a greater decrease in odorant concentrations in wines closed with synthetic corks compared to natural corks and screw caps. ...

  • quantitative analysis of 3 alkyl 2 Methoxypyrazines in juice and wine using stable isotope labelled internal standard assay
    Journal of Chromatography A, 2008
    Co-Authors: Yorgos Kotseridis, Debbie Inglis, Ian D. Brindle, M Spink, X Chen, G Soleas, A Blake, Mark K Sears, Gary J. Pickering
    Abstract:

    Abstract A solid phase microextraction (HS-SPME)–GC–MS methodology was established for the analysis of 3-alkyl-2-Methoxypyrazines (MPs) in wine using a stable isotope dilution assay. The compounds analysed were 3-isobutyl-2-methoxypyrazine (IBMP), 3- sec -butyl-2-methoxypyrazine (SBMP), and 3-isopropyl-2-methoxypyrazine (IPMP) using their respective deuterated analogues ([ 2 H 3 ]-IBMP, [ 2 H 3 ]-SBMP, [ 2 H 3 ]-IPMP) as internal standards, synthesised during this work. A divinylbenzene/carboxene/polydimethylsiloxane (DVB/CAR/PDMS) fibre was selected for isolation of MPs and the effects of matrix parameters such as pH and ethanol concentration were examined in the development of the method. Best results were obtained at a pH of approximately 6 and with a wine dilution factor of 1:2.5, resulting in an ethanol concentration of approximately 5% (v/v). Relative standard deviations (RSDs) of replicate samples were 5.6–7% for all MPs at 5 ng L −1 and −1 samples. The limit of detection was −1 in juice and 1–2 ng L −1 in wine. The recovery efficiencies for spiked wine samples were between 99 and 102% for all three MPs. Using this method, we investigated the impact of the Multicoloured Asian Lady Beetle (MALB) on MPs in wine. In red wine fermented with live MALB, IPMP is the most prevalent MP detected, although SBMP concentrations are also increased and IBMP is unchanged from background levels. MALB that have been dead for 1 day before addition to juice can still contribute to elevated SBMP concentrations in wine, but not if they have been dead for 3 days or longer. Clarifying juice prior to fermentation leads to substantially lower IPMP concentration in the subsequent wine when compared with unclarified juice.

  • Headspace gas chromatography-mass spectrometry: a fast approach to the identification and determination of 2-alkyl-3- methoxypyrazine pheromones in ladybugs
    The Analyst, 2004
    Co-Authors: Erasmus Cudjoe, Tara B. Wiederkehr, Ian D. Brindle
    Abstract:

    Static headspace sampling technique coupled with gas chromatography and mass spectrometry was used to investigate the presence of volatile 2-alkyl-3-Methoxypyrazines in three different species of ladybugs of the Coccinellidae family. The species investigated were Coccinella septempunctata, Harmonia axyridis and Hippodemia convergens. 2-isopropyl-3-methoxypyrazine (IPMP) was identified in all three species with detectable levels of 2-sec-butyl-3-methoxypyrazine (SBMP) and 3-isobutyl-2-Methoxypyrazines (IBMP) in only Hippodemia convergens and Harmonia axyridis species. Relative amounts of 2-alkyl-3-Methoxypyrazines based on body mass showed that Hippodemia convergens had the highest levels of all three Methoxypyrazines and Coccinella septempunctata the least.

Ariel R Fontana - One of the best experts on this subject based on the ideXlab platform.

  • Accurate determination of 3-alkyl-2-Methoxypyrazines in wines by gas chromatography quadrupole time-of-flight tandem mass spectrometry following solid-phase extraction and dispersive liquid-liquid microextraction.
    Journal of chromatography. A, 2017
    Co-Authors: Ariel R Fontana, Isaac Rodríguez, Rafael Cela
    Abstract:

    Abstract A new reliable method for the determination 3-alkyl-2-Methoxypyrazines (MPs) in wine samples based on the sequential combination of solid-phase extraction (SPE), dispersive liquid–liquid microextraction (DLLME) and gas chromatography (GC) quadrupole time-of-flight accurate tandem mass spectrometry (QTOF-MS/MS) is presented. Primary extraction of target analytes was carried out by using a reversed-phase Oasis HLB (200 mg) SPE cartridge combined with acetonitrile as elution solvent. Afterwards, the SPE extract was submitted to DLLME concentration using 0.06 mL carbon tetrachloride (CCl4) as extractant. Under final working conditions, sample concentration factors above 379 times and limits of quantification (LOQs) between 0.3 and 2.1 ng L−1 were achieved. Moreover, the overall extraction efficiency of the method was unaffected by the particular characteristics of each wine; thus, accurate results (relative recoveries from 84 to 108% for samples spiked at concentrations from 5 to 25 ng L−1) were obtained using matrix-matched standards, without using standard additions over every sample. Highly selective chromatographic records were achieved considering a mass window of 5 mDa, centered in the quantification product ion corresponding to each compound. Twelve commercial wines, elaborated with grapes from different varieties and geographical origins, were processed with the optimized method. The 2-isobutyl-3-methoxypyrazine (IBMP) was determined at levels above the LOQs of the method in half of the samples.

  • quechers method for the determination of 3 alkyl 2 Methoxypyrazines in wines by gas chromatography mass spectrometry
    Food Analytical Methods, 2016
    Co-Authors: Ariel R Fontana, Ruben Bottini
    Abstract:

    A new method for determining 3-isopropyl-2-methoxypyrazine, 3-sec-butyl-2-methoxypyrazine, and 3-isobutyl-2-methoxypyrazine in wines is presented. A modified quick, easy, cheap, effective, rugged, and safe method and gas chromatography-mass spectrometry (GC-MS) were used for sample preparation and compound determination, respectively. The analytes were extracted from wine (30 mL) with 1 mL toluene, in the presence of 12 g anhydrous MgSO4 and 3 g NaCl. Cleanup of the toluene phase was performed by a miniaturized dispersive solid-phase extraction with a combination of anhydrous CaCl2 (25 mg), anhydrous MgSO4 (25 mg), and primary-secondary amine (10 mg), which was effective for minimizing co-extractives and matrix effects. GC-MS parameters were also tuned up to optimize limits of detection between 4.2 and 7.1 ng L−1. The overall recoveries (trueness) of the method ranged between 71 and 87 % for the white and red wine samples, respectively, spiked at 40 and 100 ng L−1, with relative standard deviations below 21 %. The method was applied for the determination of target Methoxypyrazines in the samples of commercial wines from Argentina.