0000000001275528
AUTHOR
David Chassagne
Transfer of Water and Volatiles at Interfaces: Application to Complex Food Systems
International audience; During processing, storage and consumption, mass transfer of various small molecules (water, gases, flavour compounds or other solutes) occurs between the different phases in complex food products, or between complex food and its surroundings. These mass transfers can lead to physical or chemical changes and thus induce food quality modifications.The objective of this paper is to better understand the behaviour of small molecules at the interfaces, especially in model heterogeneous food systems. Different techniques have been designed to characterize mass transfers of these small molecules and their effects on food properties. In particular, techniques such as rotati…
Transferts de matière au travers des emballages au contact de produits alimentaires
Le point sur des recherches dans le domaine des transferts de matière au travers des emballages : impact sur la qualité du produit, causes de ces transferts.
Sorption of wine volatile phenols by yeast lees
The capacity of Saccharomyces cerevisiae yeast lees to sorb 4-ethylguaiacol and 4-ethylphenol was investigated in a synthetic medium and in wine. Active dried yeast was more effective when volatile phenols were diluted in red wine. Partition coefficients between wine model solution and wine yeast lees were determined and compared with those measured for dried active yeast. They showed a larger affinity of volatile phenols for wine yeast lees than for dried active yeast. The effect of yeast lees on volatile phenol sorption was sensitive to yeast autolysis level and to physicochemical parameters, such as ethanol content, temperature and pH. These results could be applied in the technology of …
Dry vs soaked wood: Modulating the volatile extractible fraction of oak wood by heat treatments
The aim of this study was to analyze the impact of the water content of wood on the concentrations of volatile compounds which can be extracted after heat treatments. Head Space-Solid Phase Micro Extraction Gas Chromatography coupled to Mass Spectrometry (HS-SPME GC-MS) has been used to compare the concentrations of six aroma compounds (vanillin, furfural, eugenol, guaiacol and cis- and trans-whisky lactones) in hydroalcoholic extracts of heated oak wood samples either previously soaked in hot water or not. Except for eugenol, concentrations of extracted aromas appeared to be lower in soaked woods than in dry woods for temperatures up to 200 °C. If a delaying effect of water could explain s…
Sorption of aroma compounds to oak wood in wine ageing conditions
National audience
Hydrolysis and sorption by Saccharomyces cerevisiae strains of Chardonnay grape must glycosides during fermentation
Abstract Different Saccharomyces cerevisiae strains were tested for their ability to hydrolyse glycosyl–glucose (G–G) compounds present in Chardonnay must during alcoholic fermentation. The determination of glycosyl–glucose during the course of the alcoholic fermentation of Chardonnay grape must revealed that S. cerevisiae is able to hydrolyse G–G during alcoholic fermentation in wine conditions. The extent of hydrolysis vary from 17 to 57% of the initial glycoside concentration. In order to confirm that decrease in G–G concentration during alcoholic fermentation is due to hydrolytic action and not to sorption phenomenon, in the first experiment, an analysis of the osidic part of Chardonnay…
Surface properties of Saccharomyces cerevisiae lees during sparkling wine ageing and their effect on flocculation
Cell surface properties were determined for the first time for lees of Saccharomyces cerevisiae, and they proved to be significantly dependent on the time of sparkling wine ageing on lees. Cell surface hydrophobicity decreased from approximately 44% to 11% of affinity to hexadecane. Electron acceptor capacity (calculated as % affinity to ethyl acetate-% affinity to decane) increased from approximately -27% to 10 % and zeta potential from approximately -4 to 6mV. Mannoproteins are released from the external cell wall layer during the autolytic process, as confirmed by TOF-SIMS analysis of the cell wall chemical composition. This could explain the modifications of lees cell surface properties…
Transfer of volatile phenols at oak wood/wine interface in a model system
Abstract In order to assess the influence of wood on the concentration of aroma compounds during ageing of wine, the transfer of volatile phenols including 4-ethylphenol, eugenol and a homologous series of guaiacols from wine to oak wood were studied in a model system at 10°C. At equilibrium most of the volatile phenols adsorbed in the wood. The results display that the amounts adsorbed depend on the nature of the volatile phenols and the botanical origin of oak wood.
Adsorption equilibria of water vapor on cork.
International audience; We report here for the first time a complete thermodynamic study of water vapor adsorption on crude cork powder and plate. Adsorption−desorption isotherms were accurately measured by thermogravimetry at 283, 298, and 313 K in a large range of relative pressure. Adsorption enthalpies were determined by calorimetry as a function of loading. Adsorption−desorption isotherms exhibit a hysteresis due to the swelling of the material. The influence of the presence of lenticels on the adsorption properties of cork is found to be negligible. A detailed analysis and interpretation of adsorption data allow proposal of an adsorption mechanism in two steps. (i) First, water adsorb…
Protease A activity and nitrogen fractions released during alcoholic fermentation and autolysis in enological conditions
Determination of protease A activity during alcoholic fermentation of a synthetic must (pH 3.5 at 25 degrees C) and during autolysis showed that a sixfold induction of protease A activity occurred after sugar exhaustion, well before 100% cell death occurred. A decrease in protease A activity was observed when yeast cell autolysis started. Extracellular protease A activity was detected late in the autolysis process, which suggests that protease A is not easily released. Evolution of amino acids and peptides was determined during alcoholic fermentation and during autolysis. Amino acids were released in early stationary phase. These amino acids were subsequently assimilated during the fermenta…
Influence of the drying processes of yeasts on their volatile phenol sorption capacity in model wine.
International audience; Volatile phenols, such as 4-ethylphenol, are responsible for a "horsey" smell in wine. Thus, the study of volatile phenol sorption in yeasts, and their subsequent elimination from wine, helps to optimize eco-friendly wine curative processes. Here, we compared the influences of spray drying, lyophilization and evaporative drying at low water activity on yeast, for improving the 4-ethylphenol sorption capacity in a synthetic model wine. The changes that occur in the physico-chemical characteristics of the yeast surface (surface hydrophobicity, electron-donor character and zeta potential) during these drying processes were determined to assess if any correlation exists …
Diffusion of oxygen in cork.
International audience; This work reports measurements of effective oxygen diffusion coefficient in raw cork. Kinetics of oxygen transfer through cork is studied at 298 K thanks to a homemade manometric device composed of two gas compartments separated by a cork wafer sample. The first compartment contains oxygen, whereas the second one is kept under dynamic vacuum. The pressure decrease in the first compartment is recorded as a function of time. The effective diffusion coefficient D-eff is obtained by applying Fick's law to transient state using a numerical method based on finite differences. An analytical model derived from Fick's law applied to steady state is also proposed. Results give…
Transfer of Water and Active Molecules at the Interfaces in Complex Food Systems: Theoretical and Practical Aspects
Abstract During processing, storage and consumption, mass transfer of various molecules (water, gases, flavour compounds or other solutes) occur between the different phases in complex food products, and/or also between the complex food and its surroundings. These mass transfers can lead to physical and/or chemical changes and thus induce food quality modifications. The objective of this presentation is to better understand the behaviour of small molecules at the interfaces, especially in model heterogeneous food systems. Different techniques have been developed to characterize their properties and their impact on the mass transfers. Particularly, techniques such as rotative diffusion cell …
Sorption Equilibria of Ethanol on Cork
International audience; We report here for the first time a thermodynamic study of gaseous ethanol sorption on raw cork powder and plate. Our study aims at a better understanding of the reactivity of this material when used as a stopper under enological conditions, thus in close contact with a hydroethanolic solution, wine. Sorption−desorption isotherms were accurately measured by thermogravimetry at 298 K in a large range of relative pressures. Sorption enthalpies were determined by calorimetry as a function of loading. Sorption−desorption isotherms exhibit a hysteresis loop probably due to the swelling of the material and the absorption of ethanol. Surprisingly, the sorption enthalpy of e…
Different Sorption Behaviors for Wine Polyphenols in Contact with Oak Wood
The evolution of polyphenols of enological interest- monomeric anthocyanins, (+)-catechin, (-)-epicatechin, gallic acid, and trans-resveratrol-in the presence of oak wood was investigated in aging-model conditions. Disappearance kinetics showed that, except for gallic acid, all of the wine polyphenols tend to disappear from the model wine in presence of oak wood, to reach an equilibrium after 20 days of contact. At equilibrium, the higher disappearance rates were obtained for monomeric anthocyanins and trans-resveratrol with values of 20 and 50%, respectively. For monomeric anthocyanins, the rate of disappearance seemed to be independent of their nature. In order to evaluate the contributio…
Sorption and diffusion properties of volatile phenols into cork
International audience; The sorption and diffusion properties of seven common volatile phenols in hydro-alcoholic medium placed in contact with natural cork were investigated to determine the influence of cork closures on the concentration of these compounds in wine. Weighted cork samples were immersed in model wine solutions containing selected concentrations of each compound and were sampled over time. Sorption coefficients ranged between 125 and 306 mg of aroma compound per kg of cork, while diffusion coefficients varied from 0.8 to 4.1 × 10−11 m2/s. Sorption isotherms of guaiacol and 4-propylguaiacol, respectively, the lowest and highest sorbed compounds of an homologous series of guaia…
The chemodiversity of wines can reveal a metabologeography expression of cooperage oak wood
Wine chemical compositions, which result from a complex interplay between environmental factors, genetic factors, and viticultural practices, have mostly been studied using targeted analyses of selected families of metabolites. Detailed studies have particularly concerned volatile and polyphenolic compounds because of their acknowledged roles in the organoleptic and therapeutic properties. However, we show that an unprecedented chemical diversity of wine composition can be unraveled through a nontargeted approach by ultrahigh-resolution mass spectrometry, which provides an instantaneous image of complex interacting processes, not easily or possibly resolvable into their unambiguous individu…
Aroma compound sorption by oak wood in a model wine
Oak wood used for wine barrels was immersed into a model wine containing eight aroma compounds (e.g., aromatic and terpene alcohols, ethyl esters, and aldehyde), for which activity coefficients in water and model wine were determined using the mutual solubility measurement. A mass balance of these volatiles considering their reactivity in model wine was established. For most of the studied aroma compounds, and mainly for linalool and ethyl octanoate, a sorption behavior into wood was reported for the first time. This phenomenon was selective and could not be related to the solubilities in model wine and hydrophobicities of the studied aroma compounds, suggesting that acid-base and polar cha…
Identification of passion fruit glycosides by gas chromatography/mass spectrometry
International audience
Sorption behavior of volatile phenols at the oak wood/wine interface in a model system.
The sorption in a model system of aroma compounds of enological interest (mixture of the eight derivatives from guaiacol, 4-ethylphenol, and whiskylactone) onto wood was investigated to assess the influence of wood on the concentration of these volatiles during the aging of wine. To evaluate the influence of the solubility of aroma compounds in sorption phenomena, this parameter was determined for each volatile compound in model wine at 10 and 25 degrees C. The solubility is significantly higher in the model wine than in water and remains constant in the range of temperatures studied, except for guaiacol and vanillin. Kinetic and equilibrium sorptions were investigated. Sorption kinetics sh…
Purification method for the isolation of monophosphate nucleotides from Champagne wine and their identification by mass spectrometry
Monophosphate nucleotides are difficult to identify in Champagne wine because they are present in small concentrations in a complex mixture. A method for the isolation, separation and identification of reference compounds, which achieved on average 79% recovery (except for cytidine derivatives), was developed and applied to wine. Some monophosphate nucleotides were then isolated from a Champagne wine aged on lees for 8 years, by ultrafiltration followed by a semi-preparative HPLC step using a strong anion-exchange column. The fraction obtained was subjected to HPLC in a reversed-phase column to remove the salt previously introduced, before identification of compounds by HPLC coupled to a ma…
Role of Wood Macromolecules on Selective Sorption of Phenolic Compounds by Wood
Wood is a complex structure of various macromolecules, mainly cellulose, hemicellulose, and lignin. Although the sorption process of some organic compounds by wood has been elucidated, the relative contribution of its different fractions in the sorption mechanism is not clearly determined. Certain works predict the amount of organic compounds sorbed on wood as a direct relationship to its lignin fraction. All wood macromolecules, however, seem to have the capacity to sorb organic compounds. Sorption of phenolic compounds on individual wood macromolecules has been studied and compared to that on wood. Wood-water partition coefficients ( K wood) for phenolic volatiles and their sorption rates…
Comparison of Components Released by Fermented or Active Dried Yeasts after Aging on Lees in a Model Wine
Comparison of different components released during autolysis with fermented or active dried yeast, which has never been reported previously, is related in this paper. Three autolysates were elaborated with Saccharomyces cerevisiae in a model wine (pH 3.5) at 30 or 18 degrees C. Composition of the autolysate appears to depend on both the growth medium and the physiological state of the yeast. The autolysate obtained from active dried yeast presents a higher total nitrogen concentration (a factor of 1.5-1.9 for the fermented yeast autolysate), a greater proportion of free amino acids (42 vs 16-25%), the lowest proportion of oligopeptides (25 vs 31-37%) and polypeptides (27 vs 45-34%), and an …
(−)Geosmin sorption by enological yeasts in model wine and FTIR spectroscopy characterization of the sorbent
Abstract For the first time, we report that enological yeasts or yeast cell walls can sorb (−)geosmin, an undesirable molecule that causes critical organoleptic defects in wine at low concentrations (around 50 ng l −1 ). The wine is described as “earthy” or “mouldy”. The influence of various post-harvesting processes on yeast (−)geosmin sorption capacity was studied. The dried yeast biomass obtained by the different processes was analysed by FTIR spectroscopy in ATR mode: structural differences were detected between the samples depending on the strain and the treatment used. Surface proteins and mainly phospholipids from the plasma membrane appeared to induce significantly different signals…
Wine Oxidation and the Role of Cork
The present review aims to show the state of the art of oxidation mechanisms occurring especially in white wines by taking into account knowledge from different fields in relation to the subject. It is therefore divided into three main parts. First, the mechanisms of oxidation relevant to white wine are discussed in the light of recent scientific literature. Next, the phenomenon of oxygen solubility in wine during the winemaking process, and in particular during bottling is stated theoretically as well as practically. Finally, the aspect of wine conservation after bottling is examined with respect to mass transfers which may occur through the closure, with a special emphasis on cork. Curren…
Expressing forest origins in the chemical composition of cooperage oak woods and corresponding wines by using FTICR-MS.
A non-targeted, ultra-high-resolution mass spectrometric, direct analysis of oak-wood extracts from two species (Quercus robur L. and Quercus petraea Liebl.) from three French forests, and of a wine aged in barrels derived therefrom has been performed to identify families of metabolites that could discriminate both the species and the geographical origin of woods. From 12 T ultra-high-resolution Fourier transform ion cyclotron resonance mass spectra of wood extracts, hundreds of mass signals were identified as possible significant biomarkers of the two species, with phenolic and carbohydrate moieties leading the differentiation between Q. robur and Q. petraea, respectively, as corroborated …
Interaction Mechanisms between guaiacols and lignin: the conjugated double bond makes the difference.
Lignin is considered to be responsible for a selective sorption of phenolic compounds on wood. In order to investigate the mechanisms involved, two similar guaiacol compounds--only differing by the nature of the para side chain--were adsorbed on oak wood extracted lignin. Vapor sorption-desorption isotherms indicated that about 3.5 wt % of 4-vinylguaiacol is adsorbed near saturation whereas it is only 0.8% for 4-ethylguaiacol. For both compounds, the isotherms displayed a hysteresis though significantly greater for 4-vinylguaiacol. Analyses of the hydroxyl stretching region of FTIR spectra of the lignin/4-ethylguaiacol and lignin/4-vinylguaiacol complexes indicated that physisorption via hy…
Influence of yeast autolysis after alcoholic fermentation on the development of <em>Brettanomyces</em>/<em>Dekkera</em> in wine
<p style="text-align: justify;"><em>Brettanomyces</em>, a contaminant yeast, is relatively common in wines and mainly in red wines during barrel aging. The results presented here relate to the effects of yeast lees autolysis on the growth of <em>Brettanomyces</em>. Experiments were realised in a culture medium after alcoholic fermentation, in a hydroalcoholic wine-like solution and in a red wine. <em>Brettanomyces</em> was inoculated at low level : 10<sup>2</sup> cfu/ml and the growth was controlled by counting on agar appropriate medium. Yeast lees from <em>S. cerevisiae</em> were added to these media in the presence or abse…
Wine active compounds. Proceedings of the WAC2008 international conference
International audience