Smell classification

Four characteristics of odor are subject to measurement by sensory techniques intensity, detectability, character (quality), and hedonic tone (pleasantness-unpleasantness) (16). Odor intensity is the magnitude of the perceived sensation and is classified by a descriptive scale, e.g., faint-moderate-strong, or a 1-10 numerical scale. The detectability of an odor or threshold limit is not an absolute level but depends on how the odorant is present, e.g., alone or in a mixture. Odor character or qualit) is the characteristic which permits its description or classification by comparison to other odors, i.e., sweet or sour, or like that of a skunk. The last characteristic is the hedonic type, which refers to the acceptability of an odorant. For the infrequent visitor, the smell of a large commercial bread bakery may be of high intensity but pleasant. For the nearby resident, the smell may be less acceptable. 

Classify each of the following as an intensive or extensive property of the wood samples a. color b. smell c. grain pattern of the wood d. mass e. volume and f. density. Provide justification for your classification. 

AmooreJE, Odor theory and odor classification, iniTheimer ET (ed.). Fragrance Chemistry, The Science of the Sense of Smell, Academic Press, New York, USA, pp. 21-IS, 1982. 

Hydrocarbons are divided into two main classes aliphatic and aromatic. This classification dates from the nineteenth century, when organic chemistry was devoted almost entirely to the study of materials from natural sources, and terms were coined that reflected a substance s origin. Two sources were fats and oils, and the word aliphatic was derived from the Greek word aleiphar meaning ( fat ). Aromatic hydrocarbons, irrespective of their own odor, were typically obtained by chemical treatment of pleasant-smelling plant extracts. 

Every morning students should be given unmarked smelling strips of ten or more materials selected from those to which they have already been introduced. Those that a student fails to recognize should be discussed with the teacher and fellow students and notes made in the classification. At times the materials selected by the teacher should be as different in odor type as possible at other times they should be taken from the same olfactory group, such as the rose notes, woody materials, or chemically related materials such as the acetates. Once the basic materials have been learned and understood, it is easier to add new materials. In this way the intelligent student will even be able to name materials not previously encountered. For example, the student may identify phenylethyl phenylacetate from its characteristic rose note combined with the honey note typical of the phenylacetates. 

Perfumers determine volatility by observing the behavior of perfume materials on the smelling blotter. All of the traditional classifications of volatility (Jellinek 1954 Poucher 1955 Carles 1961), and at least one more recent one (Sturm and Mansfeld 1975), are based on this approach. However, the process of evaporation from a paper strip... 

Science is not, as so many seem to think, something apart, which has to do with telescopes, retorts, and test tubes, and especially with nasty smells, but it is a way of searching out by observation, trial, and classification whether the phenomenon investigated be the outcome of human activities, or of the more direct workings of nature s laws. Its methods admit of nothing untidy or slipshod, its keynote is accuracy and its goal is truth. 

Amines are compounds in which one or more of the hydrogens of ammonia have been replaced by alkyl groups. Smaller amines are characterized by their fishy odors. Fermented shark, for example, a traditional dish in Iceland, smells exactly like trieth-ylamine. There are primary amines, secondary amines, and tertiary amines. The classification depends on how many alkyl groups are bonded to the nitrogen. Primary amines have one alkyl group bonded to the nitrogen, secondary amines have two, and tertiary amines have three. 

The sense of smell can sometimes be of use in ascertaining that the TLV of a hazardous substance has been exceeded before it is too late. J.E. Amoore and E. Hautala (Journal of Applied ToxicologyS, No. 6 (1983) 272ff) have developed an Odor Safety Factor classification with five categories the have also compiled a list of mean odor limits for 214 volatile substances based on various sources. These limits indicate the atmospheric concentration at which 50% of the test subjects, having been given prior warning, were just able to identify the odor. 

Test has been conducted for the five varieties of mango fruit only, but can be extended for other fruits where there are reasonable changes in skin color texture occur with maturity. The variations of classification performances with the variation of other factors like changes in ambient light, camera resolution, and distance of the camera were not studied. The study shows that, machine vision based system performance, is closer to the manual experts, where experts judge the mangoes maturity level not only by the skin color but also with firmness and smell. 

It is useful to be able to classify waters from the viewpoint of corrosion. Simple classifications by salt content, appearance, smell, taste, and biological properties are not sufficient. Electrical conductivity is useful, especially in relatively nonionized waters, and information on the hydrogen ion concentration (pH value) is most valuable. The major survey on zinc by Wiederholt (1965) has been supplemented by later work [e.g., Burkard and Revelly, 1979 (in French)], and there are many general accounts [e.g., Wagner, 1977 Morbe and Werner, 1978 (in German)]. 

Since the characterization of odor is critical to the technical development of medical textile materials for odor control, it is important to have a quantitative assessment method that can offer a detailed classification of body odor. In this respect, many attempts have been made to establish qualitative description and quantitative grading of body odor. For example, six descriptive terms can be used to describe axillary sweat extracts acid, chicken broth, onion, sweat (acrid), butter, and floral. The intensity of the different types of smells can be graded on an 11-point intensity scale from 0 (none) to 10 (very strong), using which a highly trained panel of assessors can carry out a reasonably accurate assessment of body odors. 

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