[Olfactometry: contribution of rhinomanometry to objective olfactometry].
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Electrodiagnosis↗
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Characterization of odorant compounds of mussels (Mytilus edulis) according to their origin using gas chromatography-olfactometry and gas chromatography-mass spectrometry.
Gas chromatography-olfactometry consists of sniffing the effluent of a gas chromatograph and leads to the direct determination of potent odorants in food. GC-olfactometry and GC-MS were applied in order to identify volatile compounds, and to characterize potent odorants of cooked wild mussels and bouchot mussels. Eighty-five volatiles were identified by GC-MS, among those the majority were identified for the first time in mussels. Using GC-olfactometry, the main contributors of cooked mussels aroma were characterized. Of the 85 volatiles identified in the flavor, only 33 were odor-active and contribute to the overall aroma of mussels. Dimethyl disulfide (sulfury odor) was the odorant the most differently perceived between the two extracts and seems to be characteristic of wild mussels. Combined GC-MS and GC-olfactometry made it possible to point out odorants which actually contribute to the aroma of cooked mussels and those which showed typical dependence on the origin of mussels.
Animals↗
Methods for gas chromatography-olfactometry: a review.
Gas chromatography-olfactometry methods are used in flavor research to determine the odor active compounds in foods. In this review, the four major methods for gas chromatography-olfactometry are described and their potentials and limitations discussed. The methods include dilution analysis, detection frequency methods, posterior intensity methods and time-intensity methods. The value of gas chromatography olfactometry data is shown to depend directly on the gas chromatography-olfactometry method, as well as on sample preparation and analytical conditions. Each of the methods has been used frequently and has its advantages and disadvantages. However, on the methodological side, a considerable area is still to be explored, which would contribute to the interpretation of the data and would improve the value of these techniques for both fundamental and applied research.
Chromatography, Gas↗
Thresholds of the dog for detection of inhaled eugenol and benzaldehyde determined by electroencephalographic and behavioral olfactometry.
Electroencephalographic olfactometry and behavioral olfactometry were developed to evaluate objectively the olfactory function of 12 dogs. These techniques were used to determined normative thresholds for benzaldehyde, a mixed olfactory and trigeminal stimulant, and eugenol, a suspected pure olfactory stimulant, in 12 dogs. Both techniques were effective in obtaining a mean threshold for clinically normal dogs. Electroencephalographic olfactometry was demonstrated to be more sensitive than was behavioral olfactometry. The techniques measured olfactory function by failure to evoke responses in dogs after ablation of olfactory mucosa. The contribution of trigeminal stimulation to the thresholds was not determined.
Animals↗
Interlaboratory comparison of dynamic olfactometry in Central Europe 2000.
This paper presents the results of an interlaboratory comparison (ringtest) on olfactometry with 31 participants from four countries in Central Europe. The aim was to give evidence of the performance of dynamic olfactometry on the basis of the European Standard prEN 13725 (Draft) "Determination of odour concentration with dynamic olfactometry. The test included the analysis of three individual substances (n-butanol, hydrogen sulphide, tetrahydrothiophen) as well as a natural odour mixture (coffee flavour) to compare mean values and the standard deviations of results for the investigated samples. It was confirmed that laboratories working in compliance with the requirements of the new standard achieve a significantly better repeatability and reproducibility than those that are not compliant.
Environmental Monitoring↗
[Respiration olfactometry--an objectifying method in the quantitative assessment of hyposmia].
The nasal flow rate is a sensitive parameter for recording respiration reactions evoked by smelling. A method is presented for objectifying measurement of different severe hyposmias. Using the monorhine respiration-olfactometry, one side of the nose is stimulated olfactorily, in the other one the nasal flow rate is registered simultaneously. 22 patients suffering from light and severe hyposmia could be exactly classified corresponding to the severity of hyposmia. There were no smell-induced respiration reactions below the detection threshold. The reaction thresholds of respiration-olfactometry correspond to the detection thresholds of subjective olfactometry in 94% of the patients.
Adolescent↗
Usefulness of word table for the quantitative evaluation of the recognition threshold in children's olfactometry.
In the quantitative evaluation of the recognition threshold in smell test, the influences of subjects' age, intelligence, and experience are unavoidable in expressing the nature of smell, especially in children. In order to avoid such individual differences, a word table has been designed in our clinic. In this study, we employed a word table for children's quantitative evaluation of the recognition threshold, and found that T & T olfactometry performed with use of a word table showed a greater reliability compared to the test without use of a word table. The use of a word table for children's olfactometry is also considered to be an easily administered procedure.
Adult↗
First attempt of odorant quantitation using gas chromatography-olfactometry.
An aroma compound was quantitated for the first time by GC-olfactometry (GC-O) on the basis of the detection frequency of odorants by a panel of 8-12 persons. The method was previously optimized regarding the coincidence of olfactometric peak apexes and the repeatability of peak height and area over 4 months. The number of required calibration points and the confidence interval of the curve were investigated. This technique was then tested by quantifying a model solution of 1-octen-3-one. The standard addition method was found to be unsuitable in this context, but external calibration gave excellent results in the ppt range. GC-O was then challenged using one of the most sensitive and selective methods, GC/MS, to quantitate 1-octen-3-one in coffee, a complex aroma. Results showed performances comparable to GC/MS/MS for this odorant, or even better as the latter required 75-500 times more sample to perform the quantitation. However, at such a low concentration, overestimation cannot be excluded with either technique because of possible coelution of odorants or isobaric ions, respectively. These results show that GC-olfactometry can compete with the most sensitive and selective techniques, such as MS, for determination of extremely intense odorants, because little sample preparation is required and there is no need for the synthesis of labeled compounds.
Calibration↗
A new approach to examine the relationships between sensory and gas chromatography-olfactometry data using Generalized Procrustes analysis applied to six French Chardonnay wines.
Six French Chardonnay wines were submitted to both sensory and combined headspace/gas chromatography-olfactometry analyses. The detection frequencies allowed five hierarchical levels to be distinguished: P25, the odorant areas (OAs) having a detection frequency > or =25% (the complete olfactogram without the odor noise); P40, > or =40%; P55, > or =55%; P70, > or =70%; and P85, > or =85%. Moreover, the detection frequencies were analyzed to distinguish 21 discriminative OAs. Wines tested by sensory analysis and the headspace samples analyzed by gas chromatography-olfactometry (GC-O) were described by a heterogeneous vocabulary distributed into nine overall classes of descriptors. The new statistical treatment to examine hierarchical or discriminative OA categories with respect to sensory data used Generalized Procrustes analysis (GPA) from coordinate tables provided by correspondence analysis (CA). The successive data sets supplied by CA were subjected to GPA to yield consensus method maps. The more selective levels of detection frequency (P70 and P85) were responsible for incomplete or distorted information with respect to sensory data. The most appropriate segmentation of the OA distribution (olfactogram) to represent the sensory profile of the six samples would correspond to the intermediate pattern (P40 and P55). The other interest was to study the reasons of distortion due to the dynamic headspace extraction. The highest proportions of the variance were at all times related to the same classes: spicy, herbaceous, and, to a lesser degree, microbiological. This would indicate that the dynamic headspace analysis induces a distortion with respect to sensory data, which systematically affected the perception of both spicy and herbaceous characters of wines.
Adult↗
Aroma components of an oil-based grill flavoring by direct thermal desorption-gas chromatography-olfactometry and sample dilution analysis.
Grill flavorings are a convenient way for food processors to impart grill-like flavor to meat products that have not been grilled. In this study a commercially available oil-based processed grill flavoring was analyzed by direct thermal desorption (DTD)-gas chromatography-olfactometry (GCO) and DTD-GC-mass spectrometry (MS). Sample mass dilution analysis-GCO was used to indicate which compounds had the greatest impact on the overall aroma of the sample. Major aroma contributors included 1-octen-3-one, 2-methoxyphenol, and (E)-2-nonenal. Minor contributors were (E)-2-decenal and 2,4-decadienal. Other major contributors, characterized as having grill aroma notes, were unidentified. Excluding the possibility of artifact formation from the thermal degradation of fatty acid hydroperoxides, DTD functioned well as a GCO technique, but poorly as a qualitative GC-MS technique.
Adsorption↗
Gc-olfactometry with solid phase microextraction of aroma volatiles from heated and unheated orange juice.
Solid phase micro extraction, SPME, the solventless headspace volatile extraction technique, was combined with GC-olfactometry (GCO) to examine changes in aroma active volatiles when orange juice was heated. Juice volatiles extracted from the static headspace using SPME (carboxen-polydimethylsiloxane fiber) were compared to liquid-liquid extracts. The SPME extract contained a greater proportion of terpenes. Limonene, myrcene and alpha-pinene comprised 86% of total FID peak area whereas they only comprised 24% in the pentane:ether extract. Aroma active volatiles were evaluated by three trained panelists using Osme, a GCO time-intensity procedure. Eighteen aroma active peaks were common to both heat treated and untreated juice headspace extracts. Six peaks were observed only in unheated extracts and five were found only in extracts from heated juices. Relative amounts of acetaldehyde decreased with increasing headspace exposure time and elevated desorption temperatures.
Adsorption↗
[Application of "subjective gustometry and olfactometry" for determination of reaction kinetics during sensorical changes in technological processes (author's transl)].
Under special conditions the "subjective gustometry and olfactometry" (SGO) allows to combine the concentration with the intensity of flavour components by theoretical means. In this way it can be used for quantitative determination of flavour concentrations as well as for kinetic measurements of sensorical changes. Thus the equations of chemical reaction kinetics (reactionorder, speed and temperature dependancy) can be used for calculation of sensorical changes as theoretically demonstrated for the formation and decomposition of different flavour components. The requirements for indicators, aroma indices, technological processes and storage conditions for a special quality criterium can also be calculated. By using the formation of cooked flavour in apple juice as a practical example the correctness of the theoretical calculations is demonstrated.
Food Inspection↗
Quantitative gas chromatography-olfactometry. Analytical characteristics of a panel of judges using a simple quantitative scale as gas chromatography detector.
Some questions related to the ability of gas chromatography-olfactometry (GC-O) to provide quantitative measurements of the concentration of a given odorant in an extract are explored and discussed. A panel of eight individuals has been used to evaluate the intensity of 15 odorants present at different concentrations. The use of very simple scales, such as a 0-3 scale, makes it possible to build calibration graphs based on the different stimulus-response models (Fechner, Stevens, Hill) and, with a proper calibration, up to nine different concentration levels can be discriminated by an eight-judge panel. The signal shows a good long-term stability, and its precision varies between 3.7 and 8% of the whole scale, with 5.7% as average. Sensitivity is extremely dependent on the compound: in the best case a concentration change of 20% can be detected, while in the worst, concentrations must differ more than one order of magnitude. In average, concentrations must differ between 2 and 4.7 times (including calibration error) or between 1.2 and 2.3 (excluding calibration error). The performance of the different judges, the effect of the close elution of two odors and the benefits derived from the use of more complex scales (7-points) are briefly discussed from the perspective of the analytical performance of GC-O methods.
Calibration↗
Significance of intravenous olfaction test using thiamine propyldisulfide (Alinamin) in olfactometry.
The significance of intravenous olfaction test in olfactometry was studied by injection of thiamine propyldisulfide (Alinamin) intravenously. An original solution of Alinamin is a thiol-type derivative of vitamin B1, and releases a mercaptan smell (garlic smell) in expired air when it arrives at the olfactory epithelium via the nasopharynx. In the intravenous olfaction test (Alinamin test), the latent time which is a period between the initiation of injection and recognition of garlic smell, and duration time which is a period between the recognition and disappearance of smell are measured. Our results indicated that latent time is influenced by olfactory acuity and duration time depends on olfactory adaptation phenomenon. Central olfactory disorders were highly suspected in hyposmia patients with duration time of less than 15 sec, and nonresponders in Alinamin test always showed poor prognosis in the recovery of olfactory acuity. It was considered that the Alinamin test is useful not only for estimating the degree of olfactory disorders, but also for differential diagnosis of impaired lesions and olfactory prognosis.
Chronic Disease↗
Importance of unilateral examination in olfactometry.
Hyposmia, the decreased sense of smell, and anosmia, the loss of sense of smell, may be unilateral or bilateral. If the olfactory acuity examined by means of bilateral test is normal, olfactory disorders are not found; unilateral examination is therefore necessary for definite evaluation of olfactory acuity. As evidence, 7 cases out of 94 patients with chronic rhinosinusitis and 6 cases out of 12 patients who received the surgery of anterior cranial fossa showed definite different olfactory threshold between nasal cavities, and there were no patients who recognized the diminished sense of smell in spite of unilateral high olfactory threshold. Additionally, we have experienced that a patient with brain tumor was diagnosed by the help of unilateral olfactory test. We thus strongly recommend the unilateral olfactometry as a method for simple and reliable test in clinical measurement of the sense of smell.
Chronic Disease↗
Quantitative gas chromatography-olfactometry carried out at different dilutions of an extract. Key differences in the odor profiles of four high-quality Spanish aged red wines.
Four Spanish aged red wines made in different wine-making areas have been extracted, and the extracts and their 1:5, 1:50, and 1:500 dilutions have been analyzed by a gas chromatography-olfactometry (GC-O) approach in which three judges evaluated odor intensity on a four-point scale. Sixty-nine different odor regions were detected in the GC-O profiles of wines, 63 of which could be identified. GC-O data have been processed to calculate averaged flavor dilution factors (FD). Different ANOVA strategies have been further applied on FD and on intensity data to check for significant differences among wines and to assess the effects of dilution and the judge. Data show that FD and the average intensity of the odorants are strongly correlated (r(2) = 0.892). However, the measurement of intensity represents a quantitative advantage in terms of detecting differences. For some odorants, dilution exerts a critical role in the detection of differences. Significant differences among wines have been found in 30 of the 69 odorants detected in the experiment. Most of these differences are introduced by grape compounds such as methyl benzoate and terpenols, by compounds released by the wood, such as furfural, (Z)-whiskey lactone, Furaneol, 4-propylguaiacol, eugenol, 4-ethylphenol, 2,6-dimethoxyphenol, isoeugenol, and ethyl vanillate, by compounds formed by lactic acid bacteria, such as 2,3-butanedione and acetoine, or by compounds formed during the oxidative storage of wines, such as methional, sotolon, o-aminoacetophenone, and phenylacetic acid. The most important differences from a quantitative point of view are due to 2-methyl-3-mercaptofuran, 4-propylguaiacol, 2,6-dimethoxyphenol, and isoeugenol.
Chromatography, Gas↗
Aromatic profile of aqueous banana essence and banana fruit by gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O).
Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O) were used to determine the aromatic composition and aroma active components of commercial banana essence and fresh banana fruit paste. Totals of 43 and 26 compounds were quantified in commercial banana essence and fresh banana fruit paste, respectively. Five new components in commercial banana essence were identified as methyl butyrate, 2,3-butanediol diacetate, 2-hydroxy-3-methylethylbutyrate, 1-methylbutyl isobutyrate, and ethyl 3-hydroxyhexanoate. A total of 42 components appear to contribute to the aromatic profile in banana. Isoamyl acetate, 2-pentanol acetate, 2-methyl-1-propanol, 3-methyl-1-butanol, 3-methylbutanal, acetal, isobutyl acetate, hexanal, ethyl butyrate, 2-heptanol, and butyl butyrate had high concentrations and were most detected by GC-O panelists in the commercial banana essence. Volatile components found only in fresh banana fruit paste that were detected by aroma panelists include E-2-hexenal, limonene, and eugenol.
Alcohols↗
Use of gas chromatography-olfactometry to identify key odorant compounds in dark chocolate. Comparison of samples before and after conching.
After vacuum distillation and liquid-liquid extraction, the volatile fractions of dark chocolates were analyzed by gas chromatography-olfactometry and gas chromatography-mass spectrometry. Aroma extract dilution analysis revealed the presence of 33 potent odorants in the neutral/basic fraction. Three of these had a strong chocolate flavor: 2-methylpropanal, 2-methylbutanal, and 3-methylbutanal. Many others were characterized by cocoa/praline-flavored/nutty/coffee notes: 2,3-dimethylpyrazine, trimethylpyrazine, tetramethylpyrazine, 3(or 2),5-dimethyl-2(or 3)-ethylpyrazine, 3,5(or 6)-diethyl-2-methylpyrazine, and furfurylpyrrole. Comparisons carried out before and after conching indicate that although no new key odorant is synthesized during the heating process, levels of 2-phenyl-5-methyl-2-hexenal, Furaneol, and branched pyrazines are significantly increased while most Strecker aldehydes are lost by evaporation.
Aldehydes↗