• TECNODOR^© General Method

The TECNODOR Olfactometer is the only instrument offering the capability for a human being to objectively quantify the perceived odor's intensity of any pleasant or unpleasant odor.

The TECNODOR's operation is based on an "Olfactory Matching" Method developed a few decades ago, but largely improved in early 1990s by METEOGLOBE.

This method consists of comparing by various means, the ambient odor's intensity with a referencing odor's intensity, which is varied in concentration until both intensities are perceived as equal by a panelist. The intensity is therefore expressed in equivalent of ppb of the referencing odor's concentration. 1-butanol is the referencing substance largely used by olfactometry specialists around the world for comparing odors intensities.

Instead of using static and discreet means of comparing odors' intensities, METEOGLOBE has developed a fully automated apparatus for generating the referencing odor concentration, from 5 ppb up to 50 000 ppb (50 ppm) with an increment of 1 ppb, providing a very large spectrum of odor intensity going from under the threshold limit of detection of 1-butanol, up to very strong odor intensities.

The TECNODOR can generate very rapidly any 1-butanol concentrations within that spectrum with a high accuracy. An embedded PC, not only used for controlling the apparatus, provides a friendly user's interface, making it easy for the panelist to focus solely on the goal of comparing the two odors' intensities, reporting each time a new concentration is generated, the relative answer. The answer is recorded by the PC for further reporting and analysis.

Due to a high performing automated iterative process, a panelist generally matches odors' intensities just after a few comparisons, normally 4 to 6.

• TECNODOR^© Detailed Method

Ultra pure air (odor free), is first presented to the panelist, under TECNODOR's Control through a specially designed cone, during 40 to 60 sec. (programmable by the operator) in order to zero down the nose excitation level, before the panelist briefly (1,5 sec) inhales the ambient odorant air, followed by the inhalation of the referencing substance.

The panelist immediately accesses the relative odors' intensities and provides its evaluation, by clicking on any one of the following buttons which appear on the screen at the end of the measurement cycle.

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Depending upon the answer given, the TECNODOR will generate during the next cycle a new concentration unknown to the panelist. In order to avoid any «memory effect» an efficient flushing process of the referencing substance's circuit takes place, before the new concentration is generated, but in parallel to the Ultra pure air presented from the other circuit to the panelist.

This cycle of referencing odor generation and odors' intensities comparison, is repeated (about every minute) until the panelist finds a good match. A panelist's test result is obtained after a few minutes. The result is expressed in ppb «equivalent of 1-butanol».

• Panel

To make sure that the final result obtained is representative, four panelists normally participate to the odor intensity evaluation.  A geometric mean is then generated by the TECNODOR. In some circumstances, like assessing product' odor under development, a well trained and experimented juror can work alone, the same if we are looking for intensity ratios downward with respect to upward of an odor reducing system. Experiments not published yet, have shown that although the absolute downward and upward values vary amongst panelists, the ratios are rather close.

• Panelists' Selection

Another important TECNODOR's function, is support for the panelists' selection process and olfactory assessment capacity's follow-up.

This is done by assessing the referencing substance perception threshold of each panelist and by verifying their capacity to properly rank different intensities. It is also possible if a mean of diluting an ambient odor is available, to obtain the «panelist's olfactory profile» (or Stevens' Slope) built upon measurements of the ambient odor's intensities at different odor's relative concentrations.

The profile which should be a straight line on a log-log graph shows the relationship between the relative Odor Intensity (I/Io) and the relative Odor Concentration (C/Co), where Io is the now well accepted «population» 1-butanol odor threshold of 40 ppb, and C/Co is the Dilution to Threshold (D/T) factor or Odor Units.

(See the TECNOGRAPH^©-Stevens' Software presentation examples for a better understanding of this concept). Sorry, not available at this moment