Olfactory quality

This methodology can be helpful in relating strict quantitative measures of olfactory quality with quantitative physicochemical measures. However, the results for this specific study suggest that the range of molecular structures and olfactory quality are too broad to derive practical information for the rational design of molecules with specific flavor qualities. 

Bitterness varies with the chemical structure of an alkaloid. With the quinolizidine alkaloids (QAs) the following scale was assessed for man Mean detection levels are 0.00085% for sparteine, 0.0021% for lupanine, and 0.017% for hydroxylupanine (503). Whereas we know a few parameters of olfactory qualities in Homo sapiens, often much less or hardly anything is known for most other vertebrates. 

Moreover, MDS has been used on neural responses to the same stimuli (Erickson Schiffman, 1975), and shows a nice match between the emerging olfactory quality space and the pattern of neural responses. Thus, smell may catch up to color and hearing in the orderliness of its quality space and in the accompanying explanatoriness of the underlying neurophysiology. But that is not overwhelmingly likely. 

This is by far the simplest method and is most often used in the lab. Indeed, it requires little or no apparatus, making it an ideal technique for both field research and sample preparation for analysis. The main drawback is the contamination of the sample with the solvent (or impurities in the solvent) that must be completely removed either to characterize the olfactory qualities of the oil or to study its biological activity. Unfortunately, often many low-molecular-weight species are lost during solvent evaporation, thereby changing, in some cases very dramatically, the aroma balance of the essential oil. 

Research in olfaction hats been impeded by a lack of knowl-ege concerning the physicochemical properties of molecules which lead to specific olfactory qualities. A diverse range of theories exists which have related quality with physicochemical properties. Factors such as molecular size and shape ( f ) low energy molecular vibrations ( ), molecular cross-section and desorption from a lipid-water interface into water ( ), proton, electron, and apolar factors (, 6 ), profile functional groups... 

Substances found by Wright and Michels to be highly correlated are located proximate to one another in this space and are expected to have similar olfactory quality. The more pleasant stimuli are located in the subset on the left, while the more unpleasant stimuli are located in the subset on the right. Siee Refs. 19 and 20. 

Figure 3. The olfactory qualities traditionally associated with (a) the stimuli in Figure 2a and (b) the stimuli in Figure 2b.

Thus, this methodology can be useful in discovering physicochemical variables relevant to olfactory quality in that it strictly relates quantitative psychophysical measures with quantitative psychophysical chemical measures. 

A predictive relationship of low energy molecular vibrations to olfactory quality utilizing a similar range of Raman spectra as in the previous example was found for this set of stimuli. 

Schiffflian, S.S. Physicochemical correlates of olfactory quality. Science, 197l I85, 112-117-... 

Computer-Assisted Studies of Chemical Structure and Olfactory Quality Using Pattern Recognition Techniques... 

Molecular structure and biological activity (olfactory quality) are related. 

Mackay-Sim, A., and Kubie, J. L., 1981, The salamander nose A model system for the study for the study of spatial coding of olfactory quality, Chem. Senses 6 249-257. 

Mackay-Sim, A., Shaman, P., and Moulton, D. G., 1982, Topographic coding of olfactory quality Odorant-specific patterns of epithelial responsivity in the salamander, J. Neurophysiol. 48 584-596. 

The olfactory qualities of the Narcissus flower have made it a valuable component of luxury perfumes since time immemorial, although the main components of the volatile part of narcissus absolute are not of alkaloidal origin. However, alkaloids are present, together with essential oils, in some iVarc 5M5-derived perfumes, such as jonquil absolute (408-410). 

Apart from their outstanding olfactory qualities, the scented compounds readily find application as fixatives. The price of Amforox is in the range of 1000 dollars per kilogram the worldwide annual production of Amfcrox and its analogues are in excess of 30 tonnes. [208]... 

An early application of a pattern recognition method to the prediction of olfactory qualities from physicochemical data was reported by Schiffman C2623. A set of 39 odorants was represented by 25 parameters (including Raman spectral information). Non-linear mapping revealed correlations of the chemical structure and smell. 

Saint-Eve, A., Pa9i Kora, E. and Martin, N. (2004). Impact of the olfactory quality and chemical complexity of the flavouring agent on the texture of low fat stirred yogurts assessed by three different sensory methodologies. Food Quality and Preference, 15, 655-668. 

Amounts. The part which esters play in the olfactory quality of wines inspired the classical studies of Berthelot on esterification. Some claim that esters are important, but others admit only that ethyl acetate is a spoilage product and detracts from the quality. Reis s (1946) results (see Tables XIV and XV) lend some support to those who believe quality and... 

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