GC olfactometry

Goodner KL, Jella P and Rouseff RL. 2000. Determination of vanillin in orange, grapefruit, tangerine, lemon, and lime juices using GC-olfactometry and GC-MS/MS. J Agric Food Chem 48(7) 2882-2886. 

Lee, S.-J. Noble, A. C. Characterization of Odor-Active Compounds in Californian Chardonnay Wines using GC-Olfactometry and GC-Mass Spectrometry. J. Agric. Food Chem. 2003, 51, 8036-8044. 

Acree, T.E. 1997. GC/Olfactometry GC with a sense of smell. Anal. Chem. 69 170A-175A. 

Deibler, K.D., Lavin, E.H., and Acree, T.E. 2002. Solid phase microextraction application in GC/olfactometry dilution analysis. In Analysis of Taste and Aroma (J.F. Jackson and H.F. Lin-skens, eds.) pp. 239-248. Springer, Berlin. 

Compound Aroma quality (GC-olfactometry) Flavour dilution factor (FD factor)... 

Silva, A.P., Odoux, E., Brat, P., Ribeyre, F., Rodriguez-Jimenes, G., Robles-Olvera, V., Garcfa-Alvarado, M.A. and Gilnata, Z. (2006) GC-MS and GC-olfactometry analysis of aroma compounds in a representative organic aroma extract from cured vanilla (Vanilla planifolia G. Jackson) beans. Food Chemistry 99(4), 728-735. 

Odor-active components in cheese flavor, many of which are derived from milk lipids, can be detected using GC-olfactometry (GC-O). GC-0 is defined as a collection of techniques that combine olfactometry, or the use of the human nose, as a detector to assess odor activity in a defined air stream post-separation using a GC (Friedich and Acree, 1988). The data generated by GC-0 are evaluated primarily by aroma extract dilution analysis or Charm analysis. Both involve evaluating the odor activity of individual compounds by sniffing the GC outlet of a series of dilutions of the original aroma extract and therefore both methods are based on the odor detection threshold of compounds. The key odourants in dairy products and in various types of cheese have been reviewed by Friedich and Acree (1988) and Curioni and Bosset (2002). 

GC-olfactometry (GC-O) brought into practice G. FI. Fuller etal. 

Aznar, M., Lopez, R., Cacho, J.F., Ferreira, V. (2001). Identification and quantification of impact odorants of aged red wines from Rioja. GC-olfactometry, quantitative GC-MS, and odor evaluation of HPLC fractions. J. Agric. Eood Chem., 49, 2924-2929. 

Lee, S.J., and Noble, A.C. (2003). Characterization of odor-active compounds in Californian Chardonnay wines using GC-olfactometry and GC-mass spectrometry. J. Agric. Food Chem., 51, 8036-8044. 

Analysis of trace compounds. All fractions were checked by capillary gas chromatography (GC) with FID and sulfiir specific detection (flame photometric detector, FPD ThermoQuest CE, Egelsbach). Subsequently the different fractions were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). Specific unknowns were enriched by preparative multidimensional gas chromatography (MDGC). For further structure elucidation complementary analyses using GC-MS and capillary gas chromatography-Fourier transform infrared spectroscopy (GC-FTIR) as well as H-NMR were applied. All new compounds have been synthesized and characterized by GC-olfactometry (GC-0). 

To detect the odour-active volatiles. Fuller et al. [6] described a system for the sniffing of GC effluents which was improved and applied to food samples by Dravnieks and O Donnell [7]. The new technique, named GC olfactometry (GCO), was the starting point for the development of a systematic approach to the identification of the compounds which cause food aromas. As summarised in Table 6.23 the analytical procedure consists of screening for key odorants by special GCO techniques, quantification and calculation of OAVs as well as aroma-recombination studies. During the last decade these steps have been critically reviewed by Acree [8], Blank [9], Grosch [10, 11 ], Mistry et al. [12] and Schieberle /fi/. 

Although many studies showed the correlation between VSCs and irradiation odor, a detailed determination of the relative contribution of individual compounds to the irradiation odor has not been available. Many techniques may be employed to address the issue. GC-olfactometry (GC-O) is a... 

Marin and co-workers [44] presented an interesting paper in 1992 on the appHcation of GC-olfactometry to the assessment of the effects of plastic polymers on the aroma character of orange juices. They used data generated from GC-FID, GC-MS and GC-Olfactometry to demonstrate the influence of hmonene contents onto the overall aroma of orange juice. The problems at hand with GC-olfactometry are mainly centred around the fact that the human nose does not have a hnear response. Hence cahbration is somewhat more tedious as the specific sensitivities to aU components are non-related to each other. 

A "good nose" can be trained in a matter of six months and usually will demonstrate a certain bias toward certain odoims. Nevertheless, once the nose "well trained", the data it generates from GC-olfactometry can be extremely useful, especially when plotted as another dimension to a regular GC-FlD, or GC-MS traces. 

Eri, S. Da Costa, N.C., Identification of volatile compounds in shiitake mushrooms using modem analytical techniques including GC-olfactometry, 7th Symposium of Flavor Chemistry and Biology, Wartburg, Germany, 2004. 

Bade-Wegner et al. (1998) studied the volatile compounds associated with the over-fermented flavor defect, considered to be one of the most objectionable organoleptic defects in coffee. They examined two defective samples of arabica and one sample of robusta green coffees, comparing them to reference products with a neutral flavor. As the off-flavor can be due to overfermentation of green coffee or to the presence of so-called stinker beans, the authors considered that the previous studies and identifications were more indicative than causative. By GC-olfactometry, three fruity odor notes were perceived, at different intensities, that were attributed to ethyl 2-methylbutanoate (Section 5,F.40), ethyl 3-methyl-butanoate (Section 5,F.41) and ethyl cyclohexanecarboxylate (Section 5,F.46). The three esters were considered to be the most important contributors to the over-fermented flavor defect. 

Very recently, Cantergiani et al. (2001) (Figure 2,11) investigated the composition of the volatile fraction of a Mexican green coffee with a pronounced earthy/mouldy off-flavor. The three components responsible were determined by GC-olfactometry, isolated, concentrated and finally characterized by GC/MS as geosmin (Section 5,B.46), 2-methylisoborneol (Section 5,B.44) and 2,4,6-trichloroanisole (Section 5,H.82), The concentrations were lower in the reference than in the defective samples. The... 

Deibler et al. (1998) propose the Flavornet database ( a new tool available on the Worldwide web , Cornell University) which contains data for over 500 compounds sorted by their chromatographic and sensory properties, the non-active odor compounds being excluded. This tool is especially useful for tentative identification of odorants found in GC-olfactometry analyses. 

These authors mention a mushroom aroma and give an odor threshold range of 2.3-5.3ppb determined by high-resolution GC olfactometry. The (S)-isomer is described with a green, vegetable mouldy flavor (Chemisis, 1999) and the (7 )-isomer with a green, mushroom meaty flavor (Chemisis, 1992). 

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