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At least 919 records · Page 51Linked to original sources
PubMed2006

Brominated flame retardants in tree bark from North America.

Brominated flame retardants were measured in 87 tree bark samples from 29 locations in North America. The concentrations of total polybrominated diphenyl ethers (PBDEs) ranged from 2.3 to 5700 ng/g lipid weight, with the highest concentrations found near or in Arkansas. A simple radial dilution model nicely describes the distribution of total PBDE concentrations in these samples and indicates the likely sources ofthese chemicals are emissions from the two brominated flame retardant manufacturing facilities, operated by Great Lakes Chemicals and Albemarle, located in southern Arkansas. The congener profiles of PBDEs are similar for all the tree bark samples and can be described by a mixture of the congener profiles of the penta- and deca-BDE commercial products combined in a ratio of 1:2. Two unusual BFRs, 1,2-bis(2,4,6-tribromophenoxy)ethane and decabromodiphenyl ethane, were also detected in tree bark samples collected in Arkansas, suggesting the two manufacturing facilities are the sources of these compounds as well. A polybrominated biphenyl congener (BB-153) was present in most tree bark samples at low levels relative to the PBDEs.

Air Pollutants↗
PubMed2002

Maturing wines in oak barrels. Effects of origin, volume, and age of the barrel on the wine volatile composition.

The influence of the oak origin, volume, and age of the barrel on the volatile composition of a red wine after six months of maturation have been studied. Major volatile compounds in wine were determined using liquid-liquid extraction with dichloromethane, and those volatiles being due to the oak were determined by extraction with pentane-ether using deuterated analogues as internal standards. The results show that there is little difference between the volatile composition of wines matured in French oak barrels and those matured in American oak barrels. The concentration of cis-oak lactone was the most significant difference. The greatest instrumental and sensory differences were found between new and used barrels, with important decreases in lactones and vanillin concentration in used barrels. When studying the effect of the volume of the barrel, the characteristics of the wine matured in 220-L new barrels versus those matured in 1000-L new barrels were very different. In new barrels, the larger the volume of the barrel, the lower the concentrations of those compounds responsible for the oaky aroma. These differences were less evident when comparing wines matured in used barrels with different capacities.

Benzaldehydes↗
PubMed2002

Evolution of phenolic compounds during an experimental aging in wood of Sherry vinegar.

Changes in the physicochemical composition of wine vinegars produced by submerged culture system and aged in wood were followed. Five Sherry wine vinegars and a model vinegar solution were aged in six new American oak butts of 16.6 L capacity. A total of 24 phenolic compounds were monitored during the maturation study (24 months), along with other physicochemical parameters (total extract, acidity, residual alcohol and total phenolic index). Multivariate statistical analysis was applied to the data. From the sixth month on, significant changes were produced in most of the phenolic compounds, mainly aromatic aldehydes and 5-(hydroxymethyl)-2-furaldehyde. When all the phenolic compounds were considered as variables, cluster analysis grouped samples according to the wine substrate employed in the elaboration of vinegars under study. Within each subcluster, samples are arranged according to their aging status when phenolic compounds accounting significative changes at 180 days of aging are considered. Discriminant functions were constructed from the phenolic compounds data set. The validity of these functions was tested using 13 samples of aged commercial Sherry wine vinegars and 25 unaged vinegars. A total of 97.4% of the test samples was correctly classified within its respective group.

Acetic Acid↗
PubMed2003

Optimization of making barrel-fermented dry muscatel wines.

The optimization of making barrel-fermented muscatel wines requires determining what type of must clarification is most suitable for the quality of the wine, as well as what type of barrel will yield the most acceptable wines. This is achieved by adding pectolytic enzymes to clarify part of the muscatel must statically; the rest is clarified by vacuum filtration. The musts obtained are fermented in French and American oak barrels and, once fermentation has ceased, they are kept with their lees for 2 months, with periodic stirring. Eleven conventional parameters and 31 volatile compounds were quantified, and a sensory analysis of the wines was produced, which led us to conclude that static clarification with pectolytic enzymes from the muscatel musts produces the best-structured wines and the larger content of higher alcohols, esters, and terpenic compounds. The wines fermented in American oak barrels received the highest overall marks, which may be due to the greater aromatic complexity given off by the compounds in the wood.

Alcohols↗
PubMed2003

Evolution of sugars in cider brandy aged in oak barrels: a contribution to its characterization.

A chemometric study was carried out to typify cider brandies according to the type of wood employed in the maturation process and their aging time. Monosaccharides, previously derivatized with p-aminobenzoic ethyl ester, were analyzed using a reversed-phase high-performance liquid chromatographic method. Univariate data treatment was not sufficient to enable differentiation of the classes of cider brandies on the basis of wood type and maturation time. Two linear combinations of original variables, ascertained by principal components analysis, provided an adequate data structurization. A mathematical decision rule was established to classify cider brandies with prediction capacities of 92 and 97% using an LDA method and Bayesian analysis, respectively. The use of the PLS algorithm allowed the authors to differentiate cider brandies according to the age and type of oak used in the aging process.

Alcoholic Beverages↗
PubMed2003

A new approach to the characterization of volatile signatures of cork wine stoppers.

This work describes a new method for the rapid characterization of volatile compounds of cork wine stoppers by a dynamic headspace method coupled to mass spectrometry (DHS-MS). This technique does not require any pretreatment of the sample. The global volatile signature of the cork is evaluated without real chromatographic separation of its constituents. For data analysis, the mass fragments of each spectrum (50 < m/z <180 amu) were considered as potential descriptors of the composition of the cork sample headspace. Chemometrics methods (principal component analysis and partial least-squares regression) were applied to extract useful information by selecting the most significant mass fragments (m/z) that allowed a good classification of the cork samples studied. In the present work, geographical origin of cork samples could be successfully characterized and predicted.

Food Packaging↗
PubMed2004

Extending applicability of the oxygen radical absorbance capacity (ORAC-fluorescein) assay.

The ORAC-fluorescein (ORAC-FL) method recently validated using automatic liquid handling systems has now been adapted to manual handling and using a conventional fluorescence microplate reader. As calculated for Trolox, the precision of the method was <3.0, expressed as percent coefficient of variation. The accuracy of the method was <2.3, expressed as percent variation of the mean. The detection and quantification limits were those corresponding to 0.5- and 1-microM Trolox standard solutions, respectively. The method has been applied to 10 pure compounds (benzoic and cinnamic acids and aldehydes, flavonoids, and butylated hydroxyanisole), to 30 white, rose, and bottled- and oak-aged red wines, and to 7 commercial dietary antioxidant supplements. All samples exhibited a good linear response with concentration. As seen by other methodologies, the chemical structure of a compound determines its antioxidant activity (ORAC-FL value). Of particular interest were the results with oak-aged red wines from different vintages (1989-2002) that confirm influence of vintage, but not origin of the oak, in the antioxidant activity of wines from the same variety. Dietary antioxidant supplements presented a great variability (170-fold difference) in their antioxidant potency. This work proves applicability of the ORAC-FL assay in evaluating the antioxidant activity of diverse food samples.

Antioxidants↗
PubMed2003

Influence of distillation system, oak wood type, and aging time on volatile compounds of cider brandy.

A study of the influence of distillation system, oak wood type, and aging time on volatile compounds of cider brandy was carried out. Acetaldehyde and acetaldehyde diethyl acetal were influenced by distillation technology, oak wood type, and maturation time. The majority ester, ethyl ethanoate, increased during aging, the highest level of this ester being detected in spirits distilled by double distillation. The alcohols of higher molecular weight were better recovered in the rectification column than in the double distillation system. Ethanoate esters decreased throughout aging of the spirits, and their degradation velocity was lower in distillates obtained from double distillation. Fatty acids and their ethyl esters presented the opposite evolution during aging, detecting an increase in ethyl esters and a decrease in their corresponding fatty acids. An increase of 1,1,3-triethoxypropane was detected during aging. French oak contributes the trans isomer of beta-methyl-gamma-octalactone and American oak contributes the cis isomer.

Acetaldehyde↗
PubMed2003

Influence of distillation system, oak wood type, and aging time on composition of cider brandy in phenolic and furanic compounds.

A control of phenolic and furanic compounds in cider brandy was carried out during maturation in oak casks, studying three technological factors: distillation (rectification column vs double distillation), oak wood type (French vs American), and aging time (32 months). Gallic acid and benzoic and cinnamic aldehydes significantly increased during maturation of cider brandies, the highest level of these phenolics being obtained when aging was conducted in French oak casks. Benzoic acids increased during aging, though furanic compounds were not influenced by the time factor. Distillation and wood factors significantly influenced furanic concentration; 5-hydroxymethylfurfural not was detected in fresh spirits and was extracted in the highest proportion in French oak. Volatile furanics, such as 5-methylfurfural, furfural, and 2-furylmethyl ketone, were influenced by the distillation factor, with the use of the double distillation system producing a higher level of these compounds. Scopoletin was the majority coumarin detected in cider brandies, the highest yield of which was obtained with the use of American oak.

Acrolein↗
PubMed2004

The effects of sample preparation and gas chromatograph injection techniques on the accuracy of measuring guaiacol, 4-methylguaiacol and other volatile oak compounds in oak extracts by stable isotope dilution analyses.

The deuterium-labeled standards [(2)H(3)]-guaiacol and [(2)H(3)]-4-methylguaiacol were synthesized and utilized in a method employing gas chromatography-mass spectrometry to determine the concentration of guaiacol and 4-methylguaiacol in wine or extracts of oak shavings. The method was combined with previously published methods for 4-ethylphenol, 4-ethylguaiacol, cis- and trans-oak lactone and vanillin, so that all these compounds could be quantified in a single analysis. The method can employ either liquid-liquid extraction or headspace solid-phase microextraction (SPME) and is rapid, robust, precise, and accurate. Under certain conditions, there was artifactual generation, to varying degrees, of guaiacol, 4-methylguaiacol, cis-oak lactone, and vanillin during the analysis of oak extracts, especially when diethyl ether extraction and injector block temperatures at or above 225 degrees C were employed. The most substantial effects were observed for guaiacol, in which results could be exaggerated by over 10 times. These artifacts could be avoided by using headspace SPME or by preparing liquid-liquid extracts with pentane or pentane/diethyl ether (2:1) injected at 200 degrees C providing spot checks using headspace SPME were performed. Data obtained for previously published quantitative determination of guaiacol in oak extracts should be reexamined carefully, with special attention paid to their respective methods of sample preparation and analysis.

Chromatography, Gas↗
PubMed2005

Sugar contents of Brandy de Jerez during its aging.

Brandy de Jerez is aged in American oak casks according to the traditional dynamic system (Soleras y Criaderas) and sometimes additionally by the static system (Anadas). The experimental arrangement used here for the analytical monitoring of brandy aging consisted of 15 casks, 12 of which were set up for aging by the dynamic system, which is well established in the denomination of origin area, whereas the other 3 contained the same brandy but aged according to the static system. This paper studies the kinetics of sugar extraction from oak wood to distillate, as well as the possible correlations between the sugar contents in brandy and its age or the commercial type it belongs to (Solera, Solera Reserva, or Solera Gran Reserva). High-performance anion-exchange chromatography with pulsed amperometric detection was used as the analytical tool to measure the concentrations of glucose, fructose, arabinose, galactose, and xylose, the presence of which in brandy has previously been described.

Alcoholic Beverages↗
PubMed2005

Characteristic volatiles from young and aged fruiting bodies of wild Polyporus sulfureus (Bull.:Fr.) Fr.

The volatile compounds of fresh fruiting bodies of wild Polyporus sulfureus (Bull.:Fr.) Fr. growing on oak trees were isolated by continuous liquid-liquid extraction (CLLE) and investigated by high-resolution gas chromatography-mass spectrometry (HRGC-MS) on two GC columns of different polarity (DB-5 and ZB-WAX), and by gas chromatography-olfactometry (GC-O). A total of 40 major volatile compounds from the young samples were identified and semiquantified. Five odorous compounds were determined to be responsible for the characteristic flavor of young Polyporus sulfureus: 1-octen-3-one, 1-octen-3-ol, 3-methylbutanoic acid, phenylethanol, and phenylacetic acid. Four volatiles investigated by GC-O and detected by GC-MS were determined as the characteristic odorants of aged species: 2-methylpropanoic acid, butanoic acid, 3-methylbutanoic acid, and phenylacetic acid. The comparative results revealed that the volatile composition of the fruiting bodies even from the same fungal species may greatly vary with its host, location, and age.

Chromatography, Gas↗
PubMed2005

Concurrent phenomena contributing to the formation of the aroma of wine during aging in oak wood: an analytical study.

Red wine was stored in different oak barrels or in stainless steel, and samples were taken for two years to determine 79 aroma compounds. Aging in oak affects 41 compounds. The type of wood affects 11 compounds. At least seven different processes seem to take place concurrently in aroma evolution, and five such processes, affecting 37 compounds, are linked to the oak cask. These are extraction from the wood, oxidation of wine alcohols and amino acids, microbiological formation of ethyl phenols, sorption processes, and condensation of acetaldehyde with polyphenols. The wood can release linear gamma- and delta-lactones, beta-damascenone, and ionones. Some compounds are released very fast from wood, which suggests they lie in the external part of the wood. Some extraction profiles are too complex to be explained by physical processes. Finally, the levels of 2,5-dimethyl-4-hydroxy-3(2H)-furanone and 2-ethyl-5-methyl-4-hydroxy-3(2H)-furanone increase even in the reference wine, which suggests the presence of a precursor.

Food Handling↗
PubMed2004

Fast screening method for volatile compounds of oak wood used for aging wines by headspace SPME-GC-MS (SIM).

A headspace solid-phase microextraction (HS-SPME) method is proposed for analyzing the main volatile components from a sensory standpoint (furfural, oak lactones, eugenol, vanillin, and syringaldehyde) present in nontoasted and toasted oak wood of different origins. To maximize the yield of compounds extracted from wood chips and to obtain a good precision of the method, the most important variables affecting HS-SPME have been studied. The best results were obtained when the sample was heated at 70 degrees C and the headspace extracted for 40 min with a DVB/CAR/PDMS fiber, which gave the overall best recovery. The values for the repeatability ranged from 6.4 to 7.8%, and those for the reproducibility from 5.4 to 8.7%. The precision of the results obtained makes the proposed technique appropriate for its use in characterizing oak wood samples of different origins and in the selection of the most suitable oak wood to age wines and spirits, on the basis of the chemical composition of the wood samples.

Food Handling↗
PubMed2005

Metabolism of antioxidant and chemopreventive ellagitannins from strawberries, raspberries, walnuts, and oak-aged wine in humans: identification of biomarkers and individual variability.

Ellagitannins (ETs) are dietary polyphenols, containing ellagic acid (EA) subunits, with antioxidant and cancer chemopreventive activities that might contribute to health benefits in humans. However, little is known about their metabolic fate. We investigate here the metabolism of different dietary ETs and EA derivatives in humans. Forty healthy volunteers were distributed in four groups. Each group consumed, in a single dose, a different ET-containing foodstuff, i.e., strawberries (250 g), red raspberries (225 g), walnuts (35 g), and oak-aged red wine (300 mL). After the intake, five urine fractions (F) were collected at 8 (F1), 16 (F2), 32 (F3), 40 (F4), and 56 (F5) h. Neither ETs nor EA were detected in urine after LC-MS/MS analysis. However, the microbial metabolite 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one (urolithin B) conjugated with glucuronic acid was detected along the fractions F3-F5 in all of the subjects, independently of the consumed foodstuff. The mean percentage of metabolite excretion ranged from 2.8 (strawberries) to 16.6% (walnuts) regarding the ingested ETs. Considerable interindividual differences were noted, identifying "high and low metabolite excreters" in each group, which supported the involvement of the colonic microflora in ET metabolism. These results indicate that urolithin B (a previously described antiangiogenic and hyaluronidase inhibitor compound) is a biomarker of human exposure to dietary ETs and may be useful in intervention studies with ET-containing products. The antioxidant and anticarcinogenic effects of dietary ETs and EA should be considered in the gastrointestinal tract whereas the study of potential systemic activities should be focused on the bioavailable urolithin B derivatives.

Adult↗
PubMed2004

Rates of formation of cis- and trans-oak lactone from 3-methyl-4-hydroxyoctanoic acid.

The rates of formation of both cis- and trans-oak lactone from the corresponding isomers of 3-methyl-4-hydroxyoctanoic acid have been measured in model wine at room temperature for a range of pH values. The half-life for formation of the trans-isomer at pH 2.9 was calculated to be 3.1 h, whereas that for the cis-isomer, at the same pH, was calculated to be 40.5 h. The k(trans)/k(cis) ratio in model wine was found to 12.86 +/- 1.34 over the range of pH values employed. A reason for the more facile formation of the trans-isomer, based on conformational reasons, has been proposed. In acidic aqueous media the equilibrium between the oak lactones and their corresponding ring-opened analogues was found to favor the former entirely, with no evidence for the latter being found. Implications of the present study for the future analysis of oak samples, as well as for the interpretation of existing data, are discussed.

Caprylates↗
PubMed2004

Aging of whiskey increases 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity.

1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of Japanese whiskey after various aging periods in oak barrels was measured to evaluate the antioxidative effects of whiskey. The activity of the whiskey increased with the aging period with high correlation. The activity of various types of whiskey was measured and shown to be correlated to the potentiation of the GABAA receptor response measured in a previous paper. However, the fragrant compounds in the whiskey which potentiated the GABAA receptor response had low DPPH radical scavenging activity, while phenol derivatives had high radical scavenging activity. The whiskey was extracted by pentane. The aqueous part showed the scavenging activity, whereas the pentane part did not. Thus, both the DPPH radical scavenging activity and the potentiation of the GABAA receptor response increased during whiskey aging in oak barrels, but were due to different components. The whiskey protected the H2O2-induced death of E. coli more than ethanol at the same concentration as that of the whiskey. The changes that occurred in the whiskey during aging may be the reason aged whiskies are so highly valued.

Alcoholic Beverages↗
PubMed2006

Physicochemical model to interpret the kinetics of aroma extraction during wine aging in wood. Model limitations suggest the necessary existence of biochemical processes.

A model based on physicochemical parameters has been developed and applied to the study of the kinetics of extraction of aroma compounds from oak casks having been used a variable number of times. Two major deviations from the model can be observed: a strong seasonal dependence of extraction (unexpected in a thermostated cellar); and higher yields with a smaller number of longer extractions. 4-Propylguaiacol follows both behaviors, and its levels have been found to be closely related to those of 4-ethylguaiacol and to the number of uses of the barrel, which suggests that this compound may be formed by the same microorganisms forming ethylphenols from a precursor found in wood. Although the extraction kinetics of all aroma compounds appear to be more or less mediated by the action of microorganisms, those of whiskeylactones, eugenol, and 4-allyl-2,6-dimethoxyphenol are more in accordance with the physicochemical model, whereas those of vanillin, syringaldehyde, furfuryl alcohol, and, of course, 4-propylguaiacol are much more coherent with a microbiological extraction/formation.

Chemical Phenomena↗