Among the various methods used to detect volatile compounds emitted by a sample, the one which is most widely used is the human nose within sensory panels. Although the human nose can be used in this way for product design, it cannot be used routinely for 100% product control in applications such as tbe monitoring of perfumes in soaps and cosmetic bases, the monitoring of body odors in deodorant development, and the monitoring of aromas in the food industry. For this reason, a few laboratories have developed “electronic noses” based on an array of gas sensors and suitable artificial intelligence. This article discusses one such electronic nose—the FOX 2000—as a new fast analytical techniqe.
The Human Nose
The outstanding capabilities of the human nose can be used either at the outlet of a gas chromatography column or directly on a product sample. To detect the volatile substances, the olfactory system uses an array of nonspecific biological sensors, the selectivity of the nose coming largely from the signal processing. Some studies have shown that the odor detection process leads at the olfactory bulb level to a spectral signature characteristic of the type of odorants, This signature, which is a kind of Fourier transform of the olfactory signals, involves the entire transduction mechanism. The patterns detected in the olfactory bulb strongly resemble the olfactory images described in some previous articles.
The odor classification is done with some oral descriptors or some subjective associations. The language used stays somewhat imprecise and is closely linked to the personal experience of each member of the sensory panel, Certain activities try, however, to use a restricted number of descriptors precise enough to describe the olfactory space associated with the studied products. Tables like those of Arctander and Moncrieff give numerous descriptors limited only by the verbal language.