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Odour perception is an important phenomenon in the animal-world. It seems worthwhile to discuss the main aspects of odour perception, such as the detection of an odour, the recognition or discrimination, the intensity and the preference.


Every living organism needs information for the maintenance of its life and species. To gather this information animals, including human beings, possess senses. By means of these senses they can communicate with their environment. With the senses of smell and taste the animal-world communicates via chemicals.

Chemical communication plays an important role in finding food and in inter-individual relations (social and sexual) and in detecting danger. With the chemical senses one may assume that a chemical substance (or mixture) interacts with a biological system resulting in a response.

The main aspects of the responses are:
- detection of the substance(s) (yes or no);
- recognition or discrimination of the odourant (qualitatively);
- rating of the intensity of the odour (weak or strong);
- determination of the preference (agreeable/disagreeable, like or dislike).

For centuries attempts have been made to correlate the structures of odourant molecules with their olfactory responses.

The odour perception by human beings, so-called human olfaction, is a part of chemoreception.
Chemoreception covers the whole field of effects resulting from the stimulation of the senses of smell and taste by chemical substances. It is a multidisciplinary science studied by chemists, physicians, biologists, physiologists, neurologists, entomologists and psychologists. Every year several thousands of publications about chemoreception appear.
Chemoreception may concern molecular processes at receptor sites, biochemical and physicochemical properties of the stimuli (odourant molecules) and of the receptors. In the case of human olfaction the responses can be verbal.

During human olfaction the main aspects of odour perception can be determined by:
- measurement of detection or recognition threshold value;
- scaling of the olfactive quality or similarity-rating of the odourants;
- intensity rating in different concentrations;
- rating of the hedonics on a preference-scale from very disagreeable to agreeable.

Sensory analysis concerns the aspects of odour determination. It covers the measurements during olfaction (odour perception through the nose) as well as those during organolepsis (perception via mouth and nose). Measurements of human olfaction are often called determinations of organoleptic qualities.

In forthcoming issues the sensory properties, such as the olfactive and organoleptic qualities, and the structural features of molecules with the following odour-types will be discussed: aromatic, green, fruity, floral, woody, musky, erogenic etc.

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