Olfactory fingerprints

Schaefer, M.L., Yamazaki, K., Osada, K., Restrepo, D. and Beauchamp, G.K. (2002) Olfactory fingerprints for major histocompatibility complex-determined body odors II relationship among odor maps, genetics, odor composition, and behavior. J. Neurosci. 22, 9513-9521. 

The artificial intelligence systems to which sensor arrays are coupled supply the closest likeness to the human olfactory system. Some of the recent theories on olfaction require that the human nose has only relatively few types of receptor, each with low specificity. The activation of differing patterns of these receptors supplies the brain with sufficient information for an odour to be described, if not recognized. As a consequence of this belief, the volatile chemical-sensing systems commercially available only contain from 6 to 32 sensors, each having relatively low specificity. Statistical methods such as principal component analysis, canonical discriminant analysis and Euclidian distances are used for mapping or linked to artificial neural nets as an aid to classification of the odour fingerprints . 

Electronic noses are vapour detection systems that mimic key principles of biological olfaction [1]. The functioning principles of biological, olfactory systems do not rely upon selective interactions with specific analytes, but rather on cross-reactive receptors [2]. The receptors respond to many odours, generating unique response patterns, which serve as fingerprints for each odour. 

The electronic nose is a technology that tends to replace/complement the human olfactory system The tool does not analyze the chemical composition of the volatile fraction, but it identifies the olfactory fingerprint. 

Thanks to special algorithms, derived from the discipline called pattern recognition, the system is able to build an olfactory map in order to allow a qualitative and quantitative analysis, discriminating a foodstuff simply by its olfactory fingerprint. 

The principle of working which operates the electronic nose is distinctly different from that of commonly used analytical instruments (e.g. gas chromatograph). The e-nose gives an overall assessment of the volatile fraction of the foodstuff that is, in large p>art responsible for the perception of the aroma of the investigated sample, without the need to seprarate and identify the various components. All the responses of the sensors resulted from the electronic nose creates a "map" of non-sp>ecific signals that constitute the profile of the food product, also called olfactory fingerprints. 

Schaefer, M.L., D. A. Young, D. Restrepo, Olfactory fingerprints for major histocom-patibUity complex-determined body odors, /. NeuroscL, 2001(21) p. 2481. 

---