Optimization and Validation of a Method to Determine Enolones and Vanillin Derivatives in Wines-Occurrence in Spanish Red Wines and Mistelles.

Understanding the chemical nature of wine aroma demands accurate quantitative determinations of different odor-active compounds. Quantitative determinations of enolones (maltol, furaneol, homofuraneol, and sotolon) and vanillin derivatives (vanillin, methyl vanillate, ethyl vanillate, and acetovanillone) at low concentrations are complicated due to their high polarity. For this reason, this paper presents an improved and automated version for the accurate measure of these common trace wine polar compounds (enolones and vanillin derivatives). As a result, a faster and more user-friendly method with a reduction of organic solvents and resins was developed and validated. The optimization of some stages of the solid phase extraction (SPE) process, such as washing with an aqueous solution containing 1% NaHCO3 at pH 8, led to cleaner extracts and solved interference problems. Due to the polarity of these type of compounds, an optimization of the large volume injection was also carried out. Finally, a programmable temperature vaporization (PTV) quartz glass inlet liner without wool was used. The injector temperature was raised to 300 °C in addition to applying a pressure pulse of 180 kPa for 4 min. Matrix effects were solved by the use of adequate internal standards, such as ethyl maltol and 3',4'-(methylenedioxy)acetophenone. Method figures of merit were highly satisfactory: good linearity (r2 > 0.98), precision (relative standard deviation, RSD < 10%), high recovery (RSD > 89%), and low detection limits (<0.7 µg/L). Enolones and vanillin derivatives are associated with wine aging. For this reason, the methodology was successfully applied to the quantification of these compounds in 16 Spanish red wines and 12 mistelles. Odor activity values (OAV) indicate that furaneol should be considered an aroma impact odorant in red wines and mistelles (OAV > 1) while homofuraneol and sotolon could also produce changes in their aroma perceptions (0.1 < OAV < 1).

Natural versus conventional production of Spanish white wines: an exploratory study.

BACKGROUND: Natural wine (NW) lacks an official or agreed definition, but it can be generally described as a wine produced with organic or biodynamic grapes with minimal intervention in the cellar, and with minimal or no use of oenological additives. The present study aimed to test the hypotheses that self-defined NWs differ from conventional wines (CW) in their chemical composition and main sensory characteristics. The levels of conventional oenological parameters, turbidity, biogenic amines, ochratoxin A, ethyl carbamate, sulphites, chlorides, some metals, major, trace and Strecker aldehyde volatile compounds were determined in 28 wines, including natural and conventional Spanish commercial white wines. Wines were also sensory described following a labelled free sorting task. RESULTS: NWs presented higher pH, volatile acidity (VA) and turbidity values, and a more intense yellow colour, whereas they have a lower malic acid content compared to theor conventional counterparts. NWs presented lower levels of total sulphur dioxide but significantly higher levels of biogenic amine putrescine, although both compounds are within the legal limits in all cases. None of the dimensions of the similarity space discriminated NWs from CWs. However, 70% of the NWs were grouped on the basis of various aromatic defects related to their higher content in 4-ethylphenols and VA. The remaining 30% were not differentiated from their conventional counterparts. CONCLUSION: It could be confirmed that NW can be globally differentiated from CW with respect to to their chemical and their sensory profiles, whereas the content in toxicants was not significantly different, with the exception of total sulphur dioxide and putrescine levels. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Accurate quantitative determination of the total amounts of Strecker aldehydes contained in wine. Assessment of their presence in table wines.

Strecker aldehydes (SAs) are key determinants of wine shelf-life and can be present in unoxidized wines in odorless forms, such as hydroxyalkylsulfonates, imines or acetals. A robust and accurate method for the determination of total forms of SAs, based on the classical derivatization with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) and in the selective solid phase extraction of derivatives has been optimized and validated. Matrix effects have been solved by the use of adequate internal standards and by large-enough equilibration times under anoxic conditions. Method figures of merit are highly satisfactory in terms of detection limits (<0.1 µg/L), linearity (R2 > 0.997), reproducibility (5-13%) and recoveries (RSDs, between 2 and 10%, for 3-methylbutanal, 14%). The analysis of total SAs in 108 Spanish wines revealed that between 52% and 70% of unoxidized red wines and likely a similar fraction of white wines, contain levels of SAs high enough to cause oxidative aromas if bound forms of SAs cleave.

Expectativas de los profesionales sanitarios sobre el beneficio obtenido por intervenciones habituales en atención primaria / Health Professionals expectations’ about the benefit of regular Primary Care interventions

Objetivo : Conocer las expectativas que expresan los profesionales sanitarios sobre el beneficio de varias intervenciones de prevención primaria, basadas en estudios de validez moderada-alta, que se realizan de forma habitual en las consultas de atención primaria.Diseño : Estudio transversal descriptivo mediante encuesta.Emplazamiento : Centros de salud españoles, entre el 6 de febrero y el 5 de mayo de 2020.Participantes : Médicos de familia y otros profesionales de atención primaria en ejercicio.Mediciones principales : a) el número y porcentaje de participantes cuya estimación de beneficio se aleja del beneficio respaldado por las evidencias; b) las magnitudes de SOBREestimación, NORMOestimación y SUBestimación de cada participante y de cada subgrupo profesional.Resultados : De los 701 respondedores (67% mujeres), 694 contestaron a las 8 preguntas y 4 entre una y 7. La sobreestimación del beneficio en las 8 intervenciones osciló entre el 86 y el 90% de todos los participantes médicos y entre el 90 y el 96% de todos los participantes enfermeros.Conclusiones : La mayoría de los profesionales encuestados sobreestiman tanto las actividades de prevención como los tratamientos preventivos, lo que les puede llevar a transmitir expectativas exageradas o falsas a los pacientes, exponerlos innecesariamente a efectos adversos derivados de esas intervenciones y a dilapidar recursos.

Aim : Examine the expectations expressed by healthcare professionals about the benefit of several primary prevention interventions that are usually carried out in The Primary Care Consultations with evidence from moderate-high validity studies.Design : Descriptive Cross-sectional Study by Survey.Sitting : Spanish Primary Healthcare Centers, between February 6 and May 5, 2020.Participants : General Practitioner and other practicing Primary Care professionals.Main measurements : a) the number and percentage of participants whose estimate of benefit deviates from the benefit supported by the evidence; b) the magnitudes of OVERestimation, NORMOestimation and UNDERestimation of each participant and each professional subgroup.Results : Of the 701 respondents (67% women), 694 answered all eight questions and 4 between one and seven. The overestimation of benefit in the 8 interventions ranged from 86% to 90% of all medical participants and between 90% and 96% of all nursing participants.Conclusions : Most of the surveyed (healthcare) professionals overestimate both, prevention activities and preventive treatments, this may lead them to instil false hope in patients, to put patients at risk of serious side effects arising from such interventions and to squander resources.

[Health Professionals expectations' about the benefit of regular Primary Care interventions]. / Expectativas de los profesionales sanitarios sobre el beneficio obtenido por intervenciones habituales en atención primaria.

AIM: Examine the expectations expressed by healthcare professionals about the benefit of several primary prevention interventions that are usually carried out in The Primary Care Consultations with evidence from moderate-high validity studies. DESIGN: Descriptive Cross-sectional Study by Survey. SITTING: Spanish Primary Healthcare Centers, between February 6 and May 5, 2020. PARTICIPANTS: General Practitioner and other practicing Primary Care professionals. MAIN MEASUREMENTS: a) the number and percentage of participants whose estimate of benefit deviates from the benefit supported by the evidence; b) the magnitudes of OVERestimation, NORMOestimation and UNDERestimation of each participant and each professional subgroup. RESULTS: Of the 701 respondents (67% women), 694 answered all eight questions and 4 between one and seven. The overestimation of benefit in the 8 interventions ranged from 86% to 90% of all medical participants and between 90% and 96% of all nursing participants. CONCLUSIONS: Most of the surveyed (healthcare) professionals overestimate both, prevention activities and preventive treatments, this may lead them to instil false hope in patients, to put patients at risk of serious side effects arising from such interventions and to squander resources.

Sensory Relevance of Strecker Aldehydes in Wines. Preliminary Studies of Its Removal with Different Type of Resins.

The orthonasal quality of two synthetic contexts of wine (young wine and oaked wine) spiked with six different levels of the Strecker aldehydes (isobutyraldehyde, 2-methylbutanal, 3-methylbutanal, methional and phenylacetaldehyde) was evaluated by a panel of wine experts. The aldehyde levels simulated the concentrations present in wines protected from oxidation during production and storage and after severe oxidation. Significant quality detriments were observed at concentrations of 13 µg/L of methional, 49 µg/L of phenylacetaldehyde, 17 µg/L of isobutyraldehyde, 12 µg/L of 2-methylbutanal and 24 µg/L of 3-methylbutanal. The presence of these levels of aldehyde concentrations induced the reduction of fruitiness in young wines and of woody notes in oaked wines as well as the appearance of the typical attributes that define wine oxidation. More than 75% of recently opened commercial wines contain total levels of Strecker aldehydes higher than those, however their effect is not always noticeable as they are forming inodorous adducts with SO2. Nevertheless, this content is a potential risk for the shelf life of the wine, as once SO2 is depleted, these aldehydes could release back into their odour-active forms. Thus, in order to reduce the presence of Strecker aldehydes, eight different resins were studied (two scavengers, four mixed-mode anion exchange and two pure anion exchange) in white wine at two levels of SO2. After 24-h contact, the mixed mode Strata X-A resin was able to significantly reduce aldehydes' percentages: between 11% for isobutyraldehyde and 86% for phenylacetaldehyde. On the other hand, wine colour was affected and therefore the applicability of the treatment should be further studied. However, this work can be considered a starting point to solve the technological challenge involved in the elimination of aldehydes from wine.

Neuroprotective Effect of Terpenoids Recovered from Olive Oil By-Products.

The neuroprotective potential of 32 natural extracts obtained from olive oil by-products was investigated. The online coupling of supercritical fluid extraction (SFE) and dynamic adsorption/desorption allowed the selective enrichment of olive leaves extracts in different terpenoids' families. Seven commercial adsorbents based on silica gel, zeolite, aluminum oxide, and sea sand were used with SFE at three different extraction times to evaluate their selectivity towards different terpene families. Collected fractions were analyzed by gas chromatography coupled to quadrupole-time-of-flight mass spectrometry (GC-QTOF-MS) to quantify the recoveries of monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), and triterpenes (C30). A systematic analysis of the neuroprotective activity of the natural extracts was then carried out. Thus, a set of in vitro bioactivity assays including enzymatic (acetylcholinesterase (AChE), butyrylcholinesterase (BChE)), and anti-inflammatory (lipoxidase (LOX)), as well as antioxidant (ABTS), and reactive oxygen and nitrogen species (ROS and RNS, respectively) activity tests were applied to screen for the neuroprotective potential of these extracts. Statistical analysis showed that olive leaves adsorbates from SS exhibited the highest biological activity potential in terms of neuroprotective effect. Blood-brain barrier permeation and cytotoxicity in HK-2 cells and human THP-1 monocytes were studied for the selected olive leaves fraction corroborating its potential.

In vitro neuroprotective potential of terpenes from industrial orange juice by-products.

Citrus sinensis (orange) by-products represent one of the most abundant citric residues from orange juice industrial production, and are a promising source of health-promoting compounds like terpenes. In this work, different extraction solvents have been employed to increase terpene extraction yield and selectivity from this orange juice by-product. A set of bioactivity assays including enzymatic (acetylcholinesterase (AChE), butylcholinesterase (BChE) and lipoxygenase (LOX)) as well as antioxidant (ABTS, reactive oxygen species (ROS) and reactive nitrogen species (RNS)) activity tests have been applied to investigate the neuroprotective potential of these compounds. New fluorescence-based methodologies were developed for AChE and BChE assays to overcome the drawbacks of these tests when used in vitro to determine the anticholinergic activity of colored extracts. Comprehensive phytochemical profiling based on gas chromatography coupled to quadrupole time of flight mass spectrometry (GC-qTOF-MS) analysis showed ahigh content of mono- and sesquiterpenes in the extracts obtained with ethyl acetate, whereas n-heptane extracts exhibited a large amount of triterpenes and carotenoids. From a neuroprotective activity point of view, ethyl acetate extract is the most promising due to its anticholinergic activity and antioxidant capacity. Finally, a multivariate data analysis revealed a good correlation between some monoterpenes (e.g. nerol or limonene) and the antioxidant capacity of the natural extract, while a group of sesquiterpenes (e.g.δ-Cadinene or nootkatone) showed correlation with the observed AChE, BChE and LOX inhibition capacity. Hydrocarbons mono- and sesquiterpenoids reveal high capacity in vitro to cross the blood-brain barrier (BBB).

Green Compressed Fluid Technologies To Extract Antioxidants and Lipids from Galdieria phlegrea in a Biorefinery Approach.

A green cascade approach was used to recover phycocyanins, carotenoids and lipids from Galdiera phlegrea. Phycocyanin extraction was performed by high pressure homogenization and purified by ultrafiltration, whereas carotenoids were obtained by a pressurized liquid extraction and lipids by supercritical fluid extraction. The second step of this innovative, green, and cost-effective procedure is able to improve the recovery of zeaxanthin and ß-carotene up to 40%, without affecting the quality of compounds and avoiding the use of organic solvents and the drying processes. The isolated carotenoids were active as antioxidants, as clearly shown by their protective activity on a cell-based model. The lipid yield was increased by 12% with respect to conventional methods.

Recent advances in mass spectrometry studies of non-covalent complexes of macrocycles - A review.

Non-covalent molecular interactions are crucial for the formation of supramolecular systems whose applications in the transport and release of drugs, the development of nanoreactors or the design of molecular sensors, among others, make them very hot topic of investigation. The use of mass spectrometry (MS) and soft ionization methods as electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) has allowed the characterization of supramolecular systems. This comprises the characterization of non-covalent complexes formed by synthetic molecules and biomolecules and the study of these host-guest systems with different molecular interactions and thermodynamic aspects. Mass spectrometry is capable of answering many questions regarding analytical characterization of these systems including composition, stoichiometry, and structural aspects as e.g., connectivities and building blocks in the supramolecular complex. These soft ionization techniques together with MS have become the technique of choice for characterizing molecular interactions allowing the design of new molecules capable of self-assembly in supramolecular systems. In this review, the synthetic macromolecules cucurbiturils, calixarenes, crown ethers, catenanes, rotaxanes and cyclodextrins are reviewed due to the wide range of non-covalent interactions that they are able to form in their supramolecular assemblies. Both the non-covalent interactions and the supramolecular structures of these synthetic molecules have been studied by mass spectrometry to characterize their structures, thus showing the power of the technique as a tool for supramolecular analysis.

Development of a robust HS-SPME-GC-MS method for the analysis of solid food samples. Analysis of volatile compounds in fresh raw beef of differing lipid oxidation degrees.

This work presents a headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for the analysis of solid food samples in extended experiments. The final procedure was used to quantify 30 volatile compounds in fresh beef. The strategy adds robustness to the classic SPME methods for solid samples, by including a control solution that solves several challenges. The control solution contained one representative compound for each studied family of beef, and two internal standards. Response factors were calculated for each family, and were subsequently applied to every compound belonging to the same family. This strategy allowed control of the quantification procedure even when the fibre, column or control solution changed. Repeatability and reproducibility had relative standard deviation values below 17%, except for phenylacetaldehyde, (E)-2-nonenal and (E,Z)-2,4-decadienal. Although the method described here was applied to animal products, it has also been successfully used to distinguish between samples from different lipid oxidation stabilities.

Formation and Accumulation of Acetaldehyde and Strecker Aldehydes during Red Wine Oxidation.

The main aim of the present work is to study the accumulation of acetaldehyde and Strecker aldehydes (isobutyraldehyde, 2-methylbutanal, isovaleraldehyde, methional, phenylacetaldehyde) during the oxidation of red wines, and to relate the patterns of accumulation to the wine chemical composition. For that, eight different wines, extensively chemically characterized, were subjected at 25°C to three different controlled O2 exposure conditions: low (10 mg L-1) and medium or high (the stoichiometrically required amount to oxidize all wine total SO2 plus 18 or 32 mg L-1, respectively). Levels of volatile aldehydes and carbonyls were then determined and processed by different statistical techniques. Results showed that young wines (<2 years-old bottled wines) hardly accumulate any acetaldehyde regardless of the O2 consumed. In contrast, aged wines (>3 years-old bottled wines) accumulated acetaldehyde while their content in SO2 was not null, and the aged wine containing lowest polyphenols accumulated it throughout the whole process. Models suggest that the ability of a wine to accumulate acetaldehyde is positively related to its content in combined SO2, in epigallocatechin and to the mean degree of polymerization, and negatively to its content in Aldehyde Reactive Polyphenols (ARPs) which, attending to our models, are anthocyanins and small tannins. The accumulation of Strecker aldehydes is directly proportional to the wine content in the amino acid precursor, being the proportionality factor much higher for aged wines, except for phenylacetaldehyde, for which the opposite pattern was observed. Models suggest that non-aromatic Strecker aldehydes share with acetaldehyde a strong affinity toward ARPs and that the specific pattern of phenylacetaldehyde is likely due to a much reduced reactivity toward ARPs, to the possibility that diacetyl induces Strecker degradation of phenyl alanine and to the potential higher reactivity of this amino acid to some quinones derived from catechin. All this makes that this aldehyde accumulates with intensity, particularly in young wines, shortly after wine SO2 is depleted.

A procedure for the measurement of Oxygen Consumption Rates (OCRs) in red wines and some observations about the influence of wine initial chemical composition.

The rates at which wine consumes oxygen are important technological parameters for whose measurement there are not accepted procedures. In this work, volumes of 8 wines are contacted with controlled volumes of air in air-tight tubes containing oxygen-sensors and are further agitated at 25 °C until O2 consumption is complete. Three exposure levels of O2 were used: low (10 mg/L) and medium or high (18 or 32 mg/L plus the required amount to oxidize all wine SO2). In each oxygen level, 2-4 independent segments following pseudo-first order kinetics were identified, plus an initial segment at which wine consumed O2 very fast. Overall, multivariate data techniques identify six different Oxygen-Consumption-Rates (OCRs) as required to completely define wine O2 consumption. Except the last one, all could be modeled from the wine initial chemical composition. Total acetaldehyde, Mn, Cu/Fe, blue and red pigments and gallic acid seem to be essential to determine these OCRs.

Ageing and retail display time in raw beef odour according to the degree of lipid oxidation.

This study aims to assess the changes in beef aroma over time when steaks from pre-aged knuckles are stored in retail display under high oxygen conditions for 15 or 22days in vacuum conditions. Odorous volatile compounds were analysed by solid-phase microextraction/gas chromatography-mass spectrometry. Results were grouped as low, medium and high oxidative groups according to thiobarbituric acid reactive substances values after 9days of display. The intensity of off-odours in the raw meat increased with ageing and display time and oxidative groups. Based on correlations between the variables and regressions of the compounds through display, eight compounds were proposed as odour shelf-life markers. Among them, five were most sensitive and precise in all oxidative groups: 1-hexanol in meat aged for 15days, ethyl- octanoate and 2-pentylfuran in meat aged for 22days, and pentanoic and hexanoic acids in the two studied ageing times.

Oxygen and SO2 Consumption Rates in White and Rosé Wines: Relationship with and Effects on Wine Chemical Composition.

This Article addresses the study of O2 and SO2 consumption rates of white and rosé wines, their relationship to the initial chemical composition, and their effects on the chemical changes experienced by wine during oxidation. Eight wines were subjected to five consecutive air-saturation cycles. O2 was monitored periodically; SO2, color, and antioxidant indexes were determined after each cycle, and the initial and final compositions of the wines were thoroughly determined. Wines consumed oxygen at progressively decreasing rates. In the last cycles, after a strong decrease, consistent increases of oxygen levels were seen. Oxygen consumption rates were satisfactorily modeled, being proportional to wine copper, quercetin, and kaempherol contents and negatively proportional to cinnamic acids. SO2 consumption rates were highly diverse between wines and were positively related to free SO2, Mn, and pH, among others. In the last saturations, SO2 consumption took place regardless of O2 consumption, implying that SO2 should reduce chemical species oxidized in previous saturations. Some volatile phenols seem to be the end point of radical-mediated oxidation of polyphenols taking place preferably in the first saturation.

Gas chromatography-mass spectrometry strategies for the accurate and sensitive speciation of sulfur dioxide in wine.

Understanding the chemistry of wine oxidation requires the accurate and sensitive quantitative determination of the most important molecular species which SO2 can form. An analytical strategy based in three independent static headspace GC-MS determinations is proposed in order to obtain information about the total, nominally free and truly free levels of SO2. Nominally free forms are directly determined after sample acidulation, total forms require the previous incubation at 100°C, and truly free forms are determined after preconcentration of the headspace of the undisturbed sample in an alkaline solution. The two first determinations provide results equivalent to those reported by the aeration-oxidation (A-O) method, with lower limits of detection (1mgL-1) and better repeatabilities (<4.0%). Results from the analysis of different wines revealed that levels of nominally free are systematically in excess than those of truly free SO2, which suggests that free SO2 determined by any method using previous acidulation includes at least two different species of SO2, which may have different antioxidant behavior.

Release and Formation of Oxidation-Related Aldehydes during Wine Oxidation.

Twenty-four Spanish wines were subjected to five consecutive cycles of air saturation at 25 °C. Free and bound forms of carbonyls were measured in the initial samples and after each saturation. Nonoxidized commercial wines contain important and sensory relevant amounts of oxidation-related carbonyls under the form of odorless bound forms. Models relating the contents in total aldehydes to the wine chemical composition suggest that fermentation can be a major origin for Strecker aldehydes: methional, phenylacetaldehyde, isobutyraldehyde, 2-methylbutanal, and isovaleraldehyde. Bound forms are further cleaved, releasing free aldehydes during the first steps of wine oxidation, as a consequence of equilibrium shifts caused by the depletion of SO2. At low levels of free SO2, de novo formation and aldehyde degradation are both observed. The relative importance of these phenomena depends on both the aldehyde and the wine. Models relating aldehyde formation rates to wine chemical composition suggest that amino acids are in most cases the most important precursors for de novo formation.

Oxygen Consumption by Red Wines. Part I: Consumption Rates, Relationship with Chemical Composition, and Role of SO2.

Fifteen Spanish red wines extensively characterized in terms of SO2, color, antioxidant indexes, metals, and polyphenols were subjected to five consecutive sensor-controlled cycles of air saturation at 25 °C. Within each cycle, O2 consumption rates cannot be interpreted by simple kinetic models. Plots of cumulated consumed O2 made it possible to define a fast and highly wine-dependent initial O2 consumption rate and a second and less variable average O2 consumption rate which remains constant in saturations 2 to 5. Both rates have been satisfactorily modeled, and in both cases they were independent of Fe and SO2 and highly dependent on Cu levels. Average rates were also related to Mn, pH, Folin, protein precipitable proanthocyanidins (PPAs), and polyphenolic profile. Initial rates were strong and negatively correlated to SO2 consumption, indicating that such an initial rate is either controlled by an unknown antioxidant present in some wines or affected by a poor real availability of SO2. Remaining unreacted SO2 is proportional to initial combined SO2 and to final free acetaldehyde.

Oxygen Consumption by Red Wines. Part II: Differential Effects on Color and Chemical Composition Caused by Oxygen Taken in Different Sulfur Dioxide-Related Oxidation Contexts.

Chemical changes caused by oxidation of red wines during 5 consecutive air-saturation cycles have been assessed. In order to investigate the existing relationship between the effects caused by O2 and the levels and consumption rates of wine SO2, the total oxygen consumed by the wines (16-25 mg/L) was subdivided into different nonmutually exclusive categories. The ones found most influential on chemical changes were the O2 consumed in the first saturation without equivalent SO2 consumption (O2preSO2) and the O2 consumed when levels of free SO2 were below 5 mg/L (radical forming O2). Chromatic changes were strongly related to both O2 categories, even though anthocyanidin degradation was not related to any O2 category. Radical forming O2 prevented both formation of red pigments and reduction of epigallocatechin and other proanthocyanidins, induced accumulation of phenolic acids, and caused losses of ß-damascenone and whiskylactone without evidence of acetaldehyde formation. O2preSO2 seemed to play a key role in the formation of blue pigments and in the decrease of Folin index and of many important aroma compounds.

Simultaneous determination of free and bonded forms of odor-active carbonyls in wine using a headspace solid phase microextraction strategy.

This paper presents a new strategy for the direct evaluation of odor-active carbonyls in the wine headspace and for the simultaneous estimation of their amounts in odorless bonded forms. In the final developed strategy, 25 mL of wine are spiked with internal and surrogate standards and let to equilibrate for at least 12 h in an oxygen-free chamber. Ten milliliter of the sample are then transferred to a standard headspace vial. Carbonyls in the headspace are preconcentrated on a PDMS/DVD fiber keeping the sample unstirred at 45°C for just 10 min and are further analyzed on a GC-MS equipped with a quadrupole in SIM mode. Normalized peak analyte areas interpolated in calibration plots built with synthetic wines give estimations of the concentrations of free forms, while the ratios of the areas of surrogates observed in wines to those observed in synthetic wine make it possible to get estimations of the proportion of each analyte present in bonded non-volatile form. The validity of this approach has been demonstrated both via standard recovery experiments and via the analysis of samples previously incubated with glyoxal in order to break aldehyde-bisulfite complexes. In general, method detection limits (below 1 µg L(-1)), precision (RSD (%)<10%) and accuracy are satisfactory for 12 studied carbonyls. Results demonstrate that wine contain relevant amounts of aldehydes (more than 95% in some cases) in the form of reversible odorless complexes, supporting a previous observation about the potential implication of these complexes on the development of oxidized aroma.