Odor measurement

Methods of Odor Measurement and Assessment (R. H. Feimer, R. M. Stuetz)... 

Two different types of odor measurements can be performed, either analytical measurements or sensory measurements (cf. Section 7.1.4). Sensory measurements are either performed by the human nose or electronic detectors and, therefore, relate to the effects of the odor (Sneath and Clarkson, 2000 Stuetz et... 

In order to harmonize an odor measurement technique, national guidelines or recommendations from Germany, France, the Netherlands and the United Kingdom are compared with respect to selection and treatment of panelists. Different methods of mathematical treatment of threshold data are also presented. 

Odor measurements must be carried out with the help of a team leader, who instructs the panelists and operates the measuring equipment. Communication between the team leader and the panel has to be kept to an absolute minimum. Because of fatigue, the duration of a test series as well as the time of the whole session should be limited. Breaks of at least the same duration as the proceeding test period should be provided. 

MANNEBECK, H., (1974). A practical portable method of odor measurement. Proceedings of the 1974 Cornell Agric. Waste Manag. Conf. Rochester, N.Y. 

Infants are able to acquire odor preferences on the first day of life. In one experiment, 12 male and 12 female white, healthy, full-term neonates were exposed to the odors of cherry or ginger on a pad taped to the inside of their crib for 24 hours. After this exposure, they were tested for preferences during active sleep (stage II). The behavior was videotaped and the duration of time oriented to each odor measured. Only the female neonates showed a preference for the familiar odor (Balogh and Porter, 1986). Therefore, even on the first day of life, females outperform males, as often described for children and adults (e.g. Yousem etal, 1999). 

Dravnieks. A. Comparison of Theories on Relations between Odor Parameters and Other Properties of Odorants, NATO Advanced Study Institute on Odor Theories and Odor Measurements. Robert College. Blebes. Istanbul. Turkey. 1966 Dyson, G.M. Raman Effect and Concept of Odor, Perfume. Essential Oil Record, 28(1937). 

Determination of the odor character and intensity of enantiomers relies heavily on complete separation of the components of the sample where there is no coelution and baseline separation of enantiomers is seen (see Fig. Gl.4.4). If these ideal conditions are not met, considerable errors will be incurred in making odor measurements, particularly in cases where both enantiomers have similar odors, or where one is odorless. Traces of odorants coeluting with analytes under investigation, tailing of peaks, and low resolution all seriously affect chromatographic odor data. If the retention times of two enantiomers differ by <1 min, quantitative odor data may be inaccurate. 

Laffort, P. "Theories of Odor and Odor Measurement Tanyolac, N.N., Ed Robert College Bebek, Istanbul, 1968 pp. 247-270. 

Wolkoff, P., Wilkins, C.K., Clausen, P.A. and Nielsen, G.D. (2006) Organic compounds in office environments-sensory irritation, odor, measurements and the role of reactive chemistry. Indoor Air, 16, 7-19. 

Special problems are related to odor measurement, its quantification and to odor policy (Frechen, 2000). Odors usually consist of many different compounds of very low concentrations that may exert synergistic or antagonistic effects. Four generally accepted dimensions of odor exist which include the concentration of odorants, the intensity of odor, its character, and its hedonic tone (i. e. its pleasantness or unpleasantness). It is extremely difficult to relate conventional analytical measurements (e. g. gas chromatographic determinations or sensor array measurements with an electronic nose ) to the intensity, character, and hedonic tone of an odor perceived by the human nose. 

It is obvious that this method of odor measurement is a very time-consuming and expensive method. However, Stuetz et al. (2000) were able to correlate the global parameters BOD, COD and TOC of sewage samples by headspace measurements of odor using a commercial sensor array system. Thus, the electronic nose seems to have several interesting applications in wastewater treatment technologies. 

To understand olfaction at a chemical level, it is necessary to have good data that link chemical structure to odor properties. This task is much more difficult than it would seem, for instance, to a chemist who sniffs a sample that he has just synthesized in the laboratory and applies an odor descriptor to the molecular structure of his synthetic target. These difficulties stem from both chemical and sensory issues. Techniques for odor measurement and the difficulties involved have been reviewed by Neuner-Jehle and Etzweiler (20). 

Sharma NC, Galaustians HJ, Qaquish J, et al. The clinical effectiveness of a dentrifice containing triclosan and a copolymer for controlling breath odor measured organoleptically twelve hours after toothbrushing. / Clin Dent 1999 10 131-134. 

These chemosensors represent the simplest of gas sensors in that their chemical reactivity is directly transduced into an electrical signal. Changes in resistance, capacitance, voltage, or current indicate the presence of a particular analyte. These types of sensors are widely used for gas and odor measurements in commercial e-nose sensor arrays. 

Van Harreveld, A.P. (Ton) Odor regulation and the history of odor measurement in Europe. In Ed. N. a. V. Office of Odor, Environmental Management Bureau, Ministry of the Environment, Government of Japan),State of the art of odour measurement, pp. 54—61 (2003) Yuwono, L. Odor Pollution in the Environment and the Detection Instrumentation, the CIGR Journal of Scientific Research and development 6 (2004)... 

It has to be remarked that in spite of the widely accepted term electronic nose, current devices are still far from the structure and functions of natural olfaction sense. The unique common feature between artificial and natural system is that both are largely based on arrays of nonselective sensors. The concept underlying electronic nose systems has been demonstrated to be independent on the particular sensor mechanism indeed during the last two decades almost all the available sensor technologies have been utilized as electronic noses. Clearly, all these sensors are very different from the natural receptors. These dissimilarities make the perception of electronic nose very different from that of natural olfaction, so that the instrumental perception of the composition of air cannot be called odor measurement because odor is the sensation of smell as perceived by human olfaction. Nonetheless, the term odor analysis with electronic noses is now largely adopted, but it is important to keep in mind, especially in medical applications, that the electronic nose measurement may be very distant from the human perception. 

Figure 1. The correlation between the mean per litter birth weight of pups and the attractiveness of the father s odor (measured as an average time per 5 min. test that females investigated their stimuli).

Example of odor determination in industrial plants Odor measurement in an industrial varnishing plant... 

Bledzki, A.K. et al. (2003) Odor measurement of natural fiber filled composites used for automotive parts. Proceedings of the 9th Annual Global Plastics Environmental Conference Plastics Impact on ihe Environment, Detroit, Ml, Society of Plastics Engineers. 

Properties Properties defined by types of chemical changes possible Description by senses such as color, shape, odor Measurable properties such as density, boihng point... 

Typical dryer exhaust emissions are sulfur compounds such as hydrogen sulfide, carbon disulfide, carbonyl sulfide, and methyl and w-propyl mercaptans. In addition to ammonia, the only amine present is trimethyl amine. Since the emissions from the dryers contain considerable moisture at temperature of about 95°C, necessary means should be provided to remove most of this moisture and to cool the air before further odor treatment. Also, there may be dust particles in the cyclone exhaust that should be removed before effective odor measures can be applied. This is normally accomplished by either direct or indirect contact (e.g., shell and tube) water-cooled condensers. The direct-contact type includes cocurrent flow venturi scrubbers and countercurrent... 

A wound-odor measurement scale offering greater discriminatory ability is a 10 cm line scale labeled numerically along the scale from 0 to 10 (0 corresponding to no wound odor, 1-4 to mildly offensive, 5-8 to moderately offensive, and 9-10 to extremely offensive ). This method can be used to monitor wound odor on a daily basis, but it can often be difhcult to compare ratings across different time periods, sessions, or settings as sensory measurement can be affected by the context in which a stimulus is assessed. In this respect, the discriminative capability of a four-point scale is better suited for assessing the improvement of wound odor in clinical practice. 

MH Woskow. Multidimensional scaling of odors. In N Tanyola9, ed. Theories of Odor and Odor Measurement. Istanbul Bebek, 1968, pp 147-188. 

A Buettner, P Schieberle. Exhaled odorant measurement (EXOM)—a new approach to quantify the degree of in-mouth release of food aroma compounds. Lebensm Wiss Technol 33 553-559, 2000. 

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