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PubMed2003

Gas chromatography-olfactometry (GC-O) and proton transfer reaction-mass spectrometry (PTR-MS) analysis of the flavor profile of grana padano, parmigiano reggiano, and grana trentino cheeses.

Gas chromatography-olfactometry (GC-O) and proton transfer reaction-mass spectrometry (PTR-MS) techniques were used to deduce the profile of odor-active and volatile compounds of three grana cheeses: Grana Padano (GP), Parmigiano Reggiano (PR), and Grana Trentino (GT). Samples for GC-O analysis were prepared by dynamic headspace extraction, while a direct analysis of the headspace formed over cheese was performed by PTR-MS. The major contributors to the odor profile were ethyl butanoate, 2-heptanone, and ethyl hexanoate, with fruity notes. A high concentration of mass 45, tentatively identified as acetaldehyde, was found by PTR-MS analysis. Low odor threshold compounds, e.g., methional and 1-octen-3-one, which contributed to the odor profile but were not detected by FID, were detected by PTR-MS. Principal component analysis on both GC-O and PTR-MS data separated the three cheese samples well and showed specific compounds related to each sample.

Adult↗
PubMed2003

Solid phase microextraction (SPME) of orange juice flavor: odor representativeness by direct gas chromatography olfactometry (D-GC-O).

The sensorial quality of solid phase microextraction (SPME) flavor extracts from orange juice was measured by direct gas chromatogrphy-olfactometry (D-GC-O), a novel instrumental tool for evaluating odors from headspace extracts. In general, odor impressions emerging from SPME extracts poorly resembled that of the original orange juice. In an attempt to improve the sensorial quality of extracts, sample equilibration and exposure times were varied on Carboxen/polydimethylsiloxane (CAR/PDMS) and divinylbenzene/Carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibers. Best sensorial results were obtained with the DVB/CAR/PDMS fiber exposed for the shortest time; a trained panel of eight assessors judged its odor as the most representative of the reference orange juice. The analysis of odor active compounds by classical GC-O accounted for odor characteristics revealed by D-GC-O. A principal component analysis (PCA) was applied on SPME and headspace extracts using flavor recoveries as variables. Interestingly, PCA discriminated samples according to their odor representations described by D-GC-O analysis. This paper provides the first comprehensive methodology to "smell" SPME extracts and "evaluate" their sensorial quality. This method will enable future investigations to further improve SPME performance.

Beverages↗
PubMed2003

Characterization of odor-active compounds in Californian chardonnay wines using GC-olfactometry and GC-mass spectrometry.

Nineteen commercial Californian Chardonnay wines were analyzed by gas chromatography-mass spectrometry (GC-MS). Freon extracts of wines were separated by silica gel chromatography into three fractions. Volatiles were quantified by GC analysis of each fraction using internal standards added to the wine prior to Freon extraction. Twelve of the 19 wines were evaluated by GC-Olfactometry (GC-O). Of the 81 compounds shown to be odor-active (OA) by GC/O, 74 were quantified and 61 were tentatively identified, all of which had been previously reported in grapes or wines. Overall concentrations of compounds with floral or oak-related aromas were higher in wines shown by descriptive analysis to be high in intensity of either floral or oak notes, respectively. The relationship between sensory intensity ratings from a previous descriptive analysis of the wines and 74 OA compounds was modeled by partial least-squares regression (PLS) analysis. This PLS model only explained 17% of the variation in the OA variables, whereas a PLS using a subset of 16 OA peaks explained 64 and 47% of variance in the sensory and GC data, respectively. Fruity wines high in peach, citrus, and floral terms were separated from those high in oak-related sensory attributes (oak, vanilla, caramel, spice, and butter). In both PLS models, the fruity and floral terms were associated with isoamyl acetate, 2-phenylethyl acetate, linalool and two unknowns exhibiting minty and bandaid-caramel odors; the oaky attributes were associated with vanillin, oak-lactones, 4-ethyl guaiacol, gamma-nonalactone, 2-acetyl furan, eugenol, 2-methoxy phenol, and two unknowns with plastic and smoky odors.

Chromatography, Gas↗
PubMed2004

Gas chromatography-olfactometry and chemical quantitative study of the aroma of six premium quality spanish aged red wines.

The aroma of six premium quality Spanish red wines has been studied by quantitative gas chromatography-olfactometry (GC-O) and techniques of quantitative chemical analysis. The GC-O study revealed the presence of 85 aromatic notes in which 78 odorants were identified, two of which-1-nonen-3-one (temptatively) and 2-acetylpyrazine-are reported in wine for the first time. Forty out of the 82 quantified odorants may be present at concentrations above their odor threshold. The components with the greatest capacity to introduce differences between these wines are ethyl phenols produced by Brettanomyces yeasts (4-ethylphenol, 4-ethyl-2-methoxyphenol, and 4-propyl-2-methoxyphenol), 2,5-dimethyl-4-hydroxy-3(2H)-furanone (furaneol), (Z)-3-hexenol, thiols derived from cysteinic precursors (4-methyl-4-mercaptopentan-2-one, 3-mercaptohexyl acetate, and 3-mercaptohexanol), some components yielded by the wood [(E)-isoeugenol, 4-allyl-2-methoxyphenol, vanillin, 2-methoxyphenol (guaiacol), and (Z)-whiskylactone], and compounds related to the metabolism (2-phenylethanol, ethyl esters of isoacids, 3-methylbutyl acetate) or oxidative degradation of amino acids [phenylacetaldehyde and 4,5-dimethyl-3-hydroxy-2(5H)-furanone (sotolon)]. The correlation between the olfactometric intensities and the quantitative data is, in general, satisfactory if olfactometric differences between the samples are high. However, GC-O fails in detecting quantitative differences in those cases in which the olfactive intensity is very high or if odors elute in areas in which the odor chromatogram is too complex.

Chromatography, Gas↗
PubMed2005

Screening for key odorants in Moroccan green olives by gas chromatography-olfactometry/aroma extract dilution analysis.

"Spanish style" Moroccan green table olives were screened for potent odorants by gas chromatography-olfactometry/aroma extraction dilution analysis of a representative Likens-Nickerson extract. (Z)-3-Hexenal [flavor dilution factor (FD) = 256], (E,E)-2,4-decadienal (FD = 128), and (E,Z)-2,4-decadienal (FD = 64) were revealed to confer green and coriander/paraffin oil odors to both fruit and oil extracts, whereas guaiacol (FD = 128) imparted a bad olive, phenolic note. Methional (3-methylthiopropionaldehyde, FD = 128) and several terpenes (FD </= 64) such as alpha-farnesene, trans-nerolidol, nerol acetate, limonene, alpha-, beta-, and gamma-terpineol, linalool, and beta-myrcene were detected in the fruit extract, although they were not reported as olive oil constituents.

Chromatography, Gas↗
PubMed2005

Prediction of the wine sensory properties related to grape variety from dynamic-headspace gas chromatography-olfactometry data.

Wine extracts obtained by a dynamic headspace sampling technique were studied by quantitative gas chromatography-olfactometry (GC-O) to determine the aroma profiles of six young monovarietal Spanish white wines. A partial least-square regression study was carried out to look for models relating wine aroma properties with GC-O scores. Models were validated by sensory analysis. Four out of the five most important sensory descriptors were satisfactorily described by a model, and sensory tests confirmed most of the predictions. The main aroma differences between these wines are due to the ratio linalool/3-mercaptohexyl acetate. Floral, sweet, and muscat are positively related to the concentration of linalool and negatively to that of 3-mercaptohexyl acetate. Tropical fruit is related to the wine content in this last odorant. 2-Phenyl acetate, reinforced by other acetates, can also contribute to floral and sweet notes. Alkyl-methoxypyrazines lessen the tropical fruit note, and acetic acid lessens the muscat nuance.

Acyclic Monoterpenes↗
PubMed2005

Impact of growing environment on chickasaw blackberry (Rubus L.) aroma evaluated by gas chromatography olfactometry dilution analysis.

The aroma extract of Chickasaw blackberry (Rubus L.) was separated with silica gel normal phase chromatography into six fractions. Gas chromatography-olfactometry (GCO) was performed on each fraction to identify aroma active compounds. Aroma extraction dilution analysis (AEDA) was employed to characterize the aroma profile of Chickasaw blackberries from two growing regions of the United States: Oregon and Arkansas. Comparative AEDA analysis showed that the berries grown in the two regions had similar aroma compositions; however, those odorants had various aroma impacts in each region. The compounds with high flavor dilution factors in Oregon's Chickasaw were ethyl butanoate, linalool, methional, trans,cis-2,6-nonadienal, cis-1,5-octadien-3-one, and 2,5-dimethyl-4-hydroxy-3(2H)-furanone, whereas in the Chickasaw grown in Arkansas, they were ethyl butanoate, linalool, methional, ethyl 2-methylbutanoate, beta-damascenone, and geraniol.

Arkansas↗
PubMed2005

Identification of potent odorants in different cultivars of snake fruit [Salacca zalacca (Gaert.) Voss] using gas chromatography-olfactometry.

Three cultivars of snake fruits, Pondoh Hitam, Pondoh Super, and Gading, were freshly extracted using liquid-liquid extraction. The aroma compounds of the three samples were analyzed by GC-MS and GC-olfactometry using the nasal impact frequency (NIF) method. A total of 24 odor-active compounds were associated with the aroma of snake fruit. Methyl 3-methylpentanoate was regarded as the character impact odorant of typical snake fruit aroma. 2-Methylbutanoic acid, 3-methylpentanoic acid, and an unknown odorant with very high intensity were found to be responsible for the snake fruit's sweaty odor. Other odorants including methyl 3-methyl-2-butenoate (overripe fruity, ethereal), methyl 3-methyl-2-pentenoate (ethereal, strong green, woody), and 2,5-dimethyl-4-hydroxy-3[2]-furanone (caramel, sweet, cotton candy-like) contribute to the overall aroma of snake fruit. Methyl dihydrojasmonate and isoeugenol, which also have odor impact, were identified for the first time as snake fruit volatiles. The main differences between the aroma of Pondoh and Gading cultivars could be attributed to the olfactory attributes (metallic, chemical, rubbery, strong green, and woody), which were perceived by most of the panelists in the Pondoh samples but were not detected in the Gading samples. This work is a prerequisite for effective selection of salak genotypes with optimal aroma profiles for high consumer acceptance.

Arecaceae↗
PubMed2005

Multidimensional gas chromatography-olfactometry for the identification and prioritization of malodors from confined animal feeding operations.

Odor profiling efforts were directed at applying to high-density livestock operations some of the lessons learned in resolving past, highly diverse, odor-focused investigations in the consumer product industry. Solid-phase microextraction (SPME) was used for field air sampling of odorous air near and downwind of a beef cattle feedyard and a swine finisher barn in Texas. Multidimensional gas chromatography-olfactometry (MDGC-O) was utilized in an attempt to define and prioritize the basic building blocks of odor character associated with these livestock operations. Although scores of potential odorant volatiles have been previously identified in high-density livestock operations, the odor profile results developed herein suggest that only a very few of these may constitute the preponderance of the odor complaints associated with these environments. This appeared to be especially true for the case of increasing distance from both cattle feedyard and swine barn facilities, with p-cresol consistently taking on the dominant odor impact role with ever increasing distance. In contrast, at- or near-site odor profiles were shown to be much more complex, with many of the well-known lower tier odorant compounds rising in relative significance. For the cattle feedyard at- or near-site odor profiles, trimethylamine was shown to represent a significantly greater individual odor impact relative to the more often cited livestock odorants such as hydrogen sulfide, the organic sulfides, and volatile fatty acids. This study demonstrates that SPME combined with a MDGC-O-mass spectrometry system can be used for the sampling, identification, and prioritization of odors associated with livestock.

Animal Feed↗
PubMed2006

Comparison of aroma volatiles in commercial Merlot and Cabernet Sauvignon wines using gas chromatography-olfactometry and gas chromatography-mass spectrometry.

Seventy-four aroma active compounds were observed in Merlot and Cabernet Sauvignon wines produced in California and Australia. Volatiles were sampled using solid phase microextraction and analyzed using time-intensity gas chromatography-olfactometry and gas chromatography-mass spectrometry (GC-MS). The most intense odorants were 3-methyl-1-butanol, 3-hydroxy-2-butanone, octanal, ethyl hexanoate, ethyl 2-methylbutanoate, beta-damascenone, 2-methoxyphenol, 4-ethenyl-2-methoxy-phenol, ethyl 3-methylbutanoate, acetic acid, and 2-phenylethanol. Aroma compounds were classified according to their aroma descriptor similarity and summed into nine distinct categories consisting of fruity, sulfury, caramel/cooked, spicy/peppery, floral, earthy, pungent/chemical, woody, and green/vegetative/fatty. Both Merlot and Cabernet Sauvignon wines were characterized by high fruity, caramel, green, and earthy aroma totals. Although there were distinct quantitative differences between Merlot and Cabernet wines, the relative aroma category profiles of the four wines were similar. Of the 66 volatiles identified by GC-MS, 28 were esters and 19 were minor alcohols. Between 81 and 88% of the total MS total ion chromatogram peak areas from each wine type were produced from only eight compounds: ethanol, ethyl octanoate, ethyl decanoate, ethyl acetate, 3-methyl-1-butanol, ethyl hexanoate, diethyl succinate, and 2-phenylethanol. Merlot wines from both Australia and California contained 4-5 times more ethyl octanoate than Cabernet Sauvignon wines from the same sources.

Chromatography, Gas↗
PubMed2000

Determination of vanillin in orange, grapefruit, tangerine, lemon, and lime juices using GC-olfactometry and GC-MS/MS.

The presence of vanillin in orange, tangerine, lemon, lime, and grapefruit juices has been identified and confirmed using high-resolution GC retention index values, mass spectra, and aroma quality. The impact of vanillin on the flavor score for grapefruit juice is discussed and reported to be minimal. Vanillin concentrations are determined to be in the low parts-per-million range for the various citrus juices. The calculated concentrations in the orange, tangerine, lemon, lime, and grapefruit juices are 0.20, 0.35, 0.41, 0.35, and 0.60 ppm, respectively. Pasteurization produced an average 15% increase in the concentration of vanillin in grapefruit juices. Vanillin did not correlate well with the overall flavor score despite a rather intense signal using OSME gas chromatography-olfactometry software.

Benzaldehydes↗
PubMed2000

Dynamic deadspace-gas chromatography-olfactometry analysis of different anatomical parts of lovage (Levisticum officinale Koch.) at eight growing stages.

Volatiles of five different parts of lovage (leaves, stems, flowers, seeds, and roots) were isolated by dynamic headspace (DHS) method and analyzed by GC-FID and GC-olfactometry (GC-O) techniques. In total, 98 compounds were identified in the samples, of which 41 are reported as lovage volatiles for the first time. Qualitative differences in the composition of DHS constituents of various anatomical parts of the plants were not significant, whereas the amounts of a number of identified volatile compounds were different in leaves, stems, flowers, seeds, and roots. Seasonal variations in the composition of headspace volatiles were also determined. Except for roots, beta-phellandrene was found to be the most abundant headspace component in all anatomical parts of lovage constituting from 36.50% to 79.28% of the total GC peak area. The sniffing panel characterized effluents from the GC column, and odor descriptors were attributed to the recognized constituents. alpha-Pinene and alpha-phellandrene/myrcene were the most frequently recognized constituents among 11 GC effluents constituting 12 identified compounds and 1 unknown compound, which were detected by the members of the sniffing panel. None of the detected constituents was recognized as a lovage character impact aroma compound.

Gas Chromatography-Mass Spectrometry↗
PubMed2000

Effects of the sniffing port air makeup in gas chromatography-olfactometry.

A time-intensity gas chromatography-olfactometry (GCO) apparatus was developed to study some aerodynamic parameters that may influence odor detection and intensity measurements by the subjects. The addition of humidified air at the elution place of the compounds is generally recommended for several reasons (essentially to prevent nasal mucosa dehydration and to improve chromatographic effluent carriage out of the column), but clues about these effects are yet to be published. This question is studied through two complementary experiments using synthetic solutions of 3-methyl-1-butanethiol, hexan-2-one, octanal, nonanal, furfural, citronellal, benzaldehyde, octan-1-ol, 2-phenylethyl acetate, guaiacol, 2-phenylethanol, and vanillin. This work demonstrates the need for an air makeup to increase odor detection frequency and intensity rating. With the conditions tested, a minimum makeup air flow rate of 50 L.min(-)(1) is necessary. On the contrary, humidification of the makeup is useless for the sniffers comfort and to improve the quantitative GCO results.

Adult↗
PubMed2000

Electroencephalographic olfactometry (EEGO) analysis of odour responses in dogs.

Scientists in many fields have studied olfaction in dogs, but no simple method exists to study this function. The olfactory ability of dogs is used in many fields. However, the owners of the dogs have a frustrating experience because there is not an easy method to measure olfactory function. The purpose of this study was to examine the characteristics of olfactory function of the dog with electroencephalographic olfactometry (EEGO) recording. It was found that slow waves decreased and rapid waves increased in response to odours. From these results, it is suggested that the rapid waves of EEGO activity are important in determining a dog's olfactory ability. The EEGO recording is effective in diagnosing anosmia in the dog and is easier than a behavioural experiment. Additionally, this method may not cause distress to an animal.

Animals↗
PubMed2006

[Subjective and objectifying olfactometry by means of flow-olfactometer].

BACKGROUND: Is the flow-olfactometer OM2S suitable for subjective and objectifying screening of olfactory function, additional to its use for chemosensory evoked potentials? METHODS: 53 normosmics were challenged prenasally and synchronously with inspiration by two short weak, moderate and strong hydrogen sulfide (H (2)S)- and phenylethyl alcohol (PEA)-stimuli. The subject pressed a button if there was an olfactory perception. The respiratory nasal pressure changes were recorded continuously via a differential pressure transducer. The alterations of breathing pattern during olfactory stimulation were calculated using a custom made LabView software. The interstimulus interval was at least 3 minutes, the respiration had to be regular. RESULTS: The detection-rate (79 - 98 %) was dependent on quality of odor and its concentration during stimulation. H (2)S-stimuli were detected more frequently than PEA-stimuli. The frequency of detection with simultaneous alteration of breathing pattern was independent of quality of odor and strength of odor concentration. 64 % of the subjects detected both weak H (2)S as well as changed synchronously their first poststimulatory breath. CONCLUSION: The H (2)S-detection threshold was estimated both by subjective data and by data of olfactory evoked respiration changes. The flow-olfactometer by Kobal is very well suitable for subjective and respiration-olfactometry, too.

Adult↗
PubMed2006

Characterization of livestock odors using steel plates, solid-phase microextraction, and multidimensional gas chromatography-mass spectrometry-olfactometry.

Livestock operations are associated with emissions of odor, gases, and particulate matter (PM). Livestock odor characterization is one of the most challenging analytical tasks. This is because odor-causing gases are often present at very low concentrations in a complex matrix of less important or irrelevant gases. The objective of this project was to develop a set of characteristic reference odors from a swine barn in Iowa and, in the process, identify compounds causing characteristic swine odor. Odor samples were collected using a novel sampling methodology consisting of clean steel plates exposed inside and around the swine barn for < or =1 week. Steel plates were then transported to the laboratory and stored in clean jars. Headspace solid-phase microextraction was used to extract characteristic odorants collected on the plates. All of the analyses were conducted on a gas chromatography-mass spectrometry-olfactometry system where the human nose is used as a detector simultaneously with chemical analysis via mass spectrometry. Multidimensional chromatography was used to isolate and identify chemicals with high-characteristic swine odor. The effects of sampling time, distance from a source, and the presence of PM on the abundance of specific gases, odor intensity, and odor character were tested. Steel plates were effectively able to collect key volatile compounds and odorants. The abundance of specific gases and odor was amplified when plates collected PM. The results of this research indicate that PM is major carrier of odor and several key swine odorants. Three odor panelists were consistent in identifying p-cresol as closely resembling characteristic swine odor, as well as attributing to p-cresol the largest odor response out of the samples. Further research is warranted to determine how the control of PM emissions from swine housing could affect odor emissions.

Animals↗
PubMed2005

A computer-based approach to assess the perception of composite odour intensity: a step towards automated olfactometry calibration.

The 2004 Nobel Prize in Physiology or Medicine laureates, Richard Axel and Linda Buck, have made smell a less enigmatic sense to study. In clinical routine, olfactory function is assessed using defined concentrations of a single defined substance, a setting which is uncommon in daily life. The present study was therefore conducted to evaluate the applicability of composite odours. Air was contaminated with different quantities of cyclohexanol, cyclohexanone and cyclohexane to generate 73 gas mixtures (one component: n = 21, two components: n = 40, three components: n = 12). The intensity of perception was estimated for each mixture by an average of 60.3 healthy individuals (4,403 assessments). An artificial neural network (ANN) was trained and validated using the contaminants' concentrations with the corresponding estimated intensities. The inter-rater variability was low, as 75.7% of the assessments did not exceed a difference beyond 0.5 from the corresponding median (considered correct predictions). The ANN correctly estimated 78.1% of the gas mixtures, and in terms of the regression task the ANN demonstrated a sufficient prediction performance (Pearson's correlation coefficient r = 0.883; R(2) = 0.757) and outperformed linear regression (r = 0.770; R(2) = 0.667). Evaluating extra ANNs for gas mixtures comprising one, two or three components, the predictive power did not decrease when complexity increased. The aforementioned results reflect nonlinearity in human perception. ANN technology helps simulate human perception of composite odour intensity which may be applicable to olfactometry calibration and systems biological mathematical modelling. The use of composite odours may represent real-life problems more adequately than single substances.

Adult↗
PubMed2000

Determination of major aroma impact compounds in fermented cucumbers by solid-phase microextraction--gas chromatography--mass spectrometry--olfactometry detection.

Purge-and-trap, solid-phase extraction, and solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) sample preparation techniques for the analysis of odor impact chemicals in fermented cucumber brine are compared. SPME-GC-MS is coupled with detection frequency olfactometry experiments to determine key impact odor compounds in the brine. The most potent odorants that define the typical characteristic brine aroma are trans-4-hexenoic acid and cis-4-hexenoic acid. Confirmation of key impact odorants in brine is confirmed by recombination experiments.

Cucumis sativus↗