Odour profiling

Sensory profiling techniques are designed to produce stable and reproducible data, but difficulties arise when trying to compare data obtained from different laboratories. Often the methods of sensory assessment differ and there is no universally accepted odour language or list of odour standards to clarify this problem. 

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Seventeen compounds were present only in boars and reproductive females giving their complex odour-profile a specific character. However, some of these compounds have been found in one of the non-reproductive females. This female also shows a much higher number of compounds compared to the other two non-reproductive females which suggests that this animal may have been at an early (undetected) stage of pregnancy. 

Xu, Y., Dixon, S. J., Brereton, R. G., Soini, H. A., Novotny, M. V., Trebesius, K., Bergmaier, I., Oberzaucher, E., Grammer, K., Penn, D. J. Metabolomics 3,2007,421-dSl. Comparison of human axillary odour profiles obtained by gas chromatography/mass spectrometry and skin microbial profiles obtained by denaturing gradient gel electrophoresis using... 

Petersen, M. A., Poll, L., Larsen, L. M. (1998). Comparison of volatiles in raw and boiled potatoes using a mild extraction technique combined with GC odour profiling and GC-MS. Food Chem., 61,461 66. 

To test the potential of PLS to predict odour quality, it was used in a QSAR study of volatile phenols. A group of trained sensory panelists used descriptive analysis (28) to provide odour profiles for 17 phenols. The vocabulary consisted of 44 descriptive terms, and a scale fiom 0 (absent) to S (very strong) was used. The panel average sensory scores for the term sweet were extracted and used as the Y-block of data, to be predicted from physico-chemical data. 

Owing to the limitations of the isolation procedures, it has to be examined sensorially whether the odour profiles of the concentrated extract and of the starting material agree (cf discussion in [8]). In the SPME procedure this check demands an extraction of the odorants from the fibre as reported in [19]. 

In the case of pineapples, the 12 odorants listed in Table 16.7 were dissolved in water in concentrations equal to those determined in the fruit [50]. Then the odour profile of this aroma model was evaluated by a sensory panel in comparison to fresh pineapple juice. The result was a high agreement in the two odour profiles. Fresh, fruity and pineapple-like odour notes scored almost the same intensities in the model as in the juice. Only the sweet aroma note was more intense in the model than in the original sample [50]. In further experiments, the contributions of the six odorants showing the highest OAV (Table 16.7) were evaluated by means of omission tests [9]. The results presented in Table 16.8 show that the omission of 4-hydroxy-2,5-dimethyl-3(2H)-furanone, ethyl 2-methylbutanoate or ethyl 2-methylpropanoate changed the odour so clearly that more than half of the assessors were able to perceive an odour difference between the reduced and the complete aroma model. Therefore, it was concluded that these compounds are the character-impact odorants of fresh pineapple juice. 

A substance is said to be chemically pure when it is made up of identical atoms and molecules. This means that the concept of purity can only apply to a single element or compound. As essential oils are made up of mixtures of organic compounds, they cannot be strictly chemically pure. Chemical purity and composition have to be related to an odour profile and be free from any contamination. Standard samples are used for reference when considering the purity of an essential oil, and the analytical techniques of GC-MS, refractive index and other methods previously described are applied. A standard sample or standard oil is a sample of a product that conforms to a specification for that product. It is kept for purposes of comparison with batch samples and used in quality evaluation. 

Figure 3B.5 shows the odour profiles of three wines as obtained using the OAV classification scheme. The example illustrates the differences between three types of wine in terms of volatile components, which have been classified into seven aroma series. 

Fig. 3B.5 Odour profiles of fino, amontillado and oloroso wines. For a better visualization the values of the fatty, fruity and spice series are divided by 5...

The intensely fruity, juicy, slightly woody and sulphurous, tropical odour profile of this oil also features a pronounced nootkatone note. 

Table 6.28 Headspace odour profiles of a baguette and the corresponding aroma model [34]...

Sulphurous and fatty odour notes predominated in the odour profile of boiled pork. It is assumed [37, 38] that the sulphurous (e.g. methanethiol) and fatty odorants (e.g. octanal, nonanal) are clearly perceptible in pork due to the much lower concentration of furaneol (Table 6.29). Although when compared to pork, the levels of octanal and nonanal were twice as high in beef (Table 6.29) the fatty odour note was weak. In particular the fourfold higher concentration of furaneol might have reduced the intensity of the fatty odour. 

The odour profile differed somewhat because the nutty, sweet and pungent odour notes were more intense in the model and the buttery note was weaker. However, the taste profile of the model matched that of the corresponding Swiss cheese sample very well ]53]. Omission experiments supported the conclusion that methional (no. 6 in Table... 

The three compounds presented in Table 6.34 are the key odorants of butter [63]. A comparison of the odour profiles of five samples of butter (Table 6.35) with the results of quantitative analysis (Table 6.34) show that the concentrations of these three odorants, which were found in samples 1 and 2, produce an intensive butter aroma. In samples 3 and 5, the concentration of 2,3-butanedione is too low and, therefore, the buttery odour quality is weak. In sample 4, the excessively high butyric acid concentration stimulates a rancid off-flavour. 

The key odorants of two olive oils, I and S, with very different odour profiles (Table 6.36) are listed in Table 6.37. The apple-like and green odour qualities, which are characteristic for oil I, are caused by aldehydes nos. 5 to 7 and 15 (Table 6.37). Their concentration is higher in oil I than in S. The very potent odorant no. 10 occurred only in oil S. As a result of its high OAV and its blackcurrant-like odour quality, it is the character impact odorant of this oil [64, 65]. 

Table 6.36 Odour profiles of virgin olive oils and their aroma models [64]...

Table 6.37 Key odorants of two olive oils with different odour profiles [64, 65]...

The odour intensities of volatiles showing similar odour qualities are partially additive [68]. To substantiate such additive effects, three groups of odorants (terpene hydrocarbons, esters or aldehydes) were omitted from the aroma model for orange juice. For all groups, a significant difference from the complete model was observed (Table 6.39). Omission of esters nos. 12,14 and 15 with ethyl butanoate (no. 13) still present was clearly detectable. This indicates that the fruity quality in the odour profile is enhanced by additive effects. In contrast, no difference was perceivable when (R)-a-pinene (no. 17) and myrcene (no. 18) were omitted. The concentration of the odorants in juice differs depending on the variety. Thus, the weaker citrus note of Navel oranges compared with the above discussed variety Valencia late is due to a 70% lower content of (R)-limonene [67]. 

The most important odorants of parsley leaves are listed in Table 6.48. An aroma model formulated on the basis of the quantitative data (Table 6.48) was described as clearly parsley-like [88]. Differences between the odour profile of the model and that of parsley leaves were observed for the spicy and the green-grassy notes which were stronger and weaker, respectively, in the model. The parsley-like character of the aroma model was completely lost when p-mentha-l,3,8-triene (no. 1 in Table 6.48) and myrcene (no. 2) were omitted [88],... 

What does this odour smell like The tests used to describe odour quality are known as odour profiling tests. These are the most complex of the sensory tests and, to ensure good quality, accurate and reproducible data are only carried out by highly trained and experienced sensory panellists. 

Each odour is smelled by the panellist, who then scores the perceived intensity of each odour character that she or he can detect (referring to the set of standard odour references for clarification if necessary), which results in a sensory profile for that odour. A minimum of at least 20 profiles is usually collected for each sample and an average profile is then calculated. A set of typical odour profiles is shown in Figure 8.3. These profiles show the differences in perceived intensity of 13 odour characteristics identified in seven perfume materials, and immediately it is possible to see that although all of the materials are floral or muguet in character, one material is far more fruity (cyclamen aldehyde) and another (Mayol ) is far more herbal than the other materials. 

Figure 8.3 Odour profiles of a selection of muguet perfumery materials Statistical Techniques...

Odour can be described using a number of different dimensions, each of which can be measured using different sensory tests threshold, intensity and quality (odour profile or qualitative descriptive analysis). 

The Saratoga Springs Symposium provided a forum for the clarification of some newly emerging fundamental questions such as the suitability of the concept of "pheromones" in work with mammals, the question of learning in chemical communication, of diet in shaping odour profiles and the effects upon chemical communication of the multisensory context in which it must operate. Also, the question of the chemical complexity of odour signals received attention. 

Biasioli,F.,Gasperi,E,Aprea,E.,Endrizzi,I.,Framondino, V, Marini, E, Mott, D., Mark,T.D. (2006) Correlation of PTR-MS spectral fingerprints with sensory characterisation of flavour and odour profile of Trentingrana cheese. Food Quality and Preference, 17, 63-75. 

Odour profile A combination of top, middle and back notes which collectively give a... 

The wide range of plant materials which have been extracted with CO2 is illustrated in the appendix which consists of a review of published literature on the yields, major components, odour profile, perceptable odour threshold and major applications for 42 botanical extracts. 

This section reviews the published literature of CO2 extraction yields, major components, odour profile, minimum perceptible threshold, major flavour and fragrance applications of 42 natural botanical extracts. 

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