Sensorially-active compounds

M. Schlosser, D. Michel, About the physiological size of fluorine substituents Comparison of sensorially active compounds with fluorine and methyl substituted analogues. Tetrahedron 52 (1996) 99-108. 

Many materials used for food and beverage packaging have characteristic odors or sensory active compounds (Torri et ah, 2008). The intensity and description of the odor may be affected by the number and type of volatile compounds that are released under environmental conditions at the time of evaluation. Chemical composition of the material and polymer morphology may play a role in the sensory characterization. Sensory descriptors do not define a specific chemical compound but may be related to different compounds, a blend of compounds, and even a limited concentration range of a compound or class of compounds. For example, frans-2-nonenal in water changes in sensory (taste) description from "plastic (0.2 gg/1) to "woody" (0.4-2.0 p.g/1), "fatty" (8-40 pg/1), and "cucumber" (1000 gg/1) (Piringer and Ruter, 2000). Such terms are descriptive of the sensation and perception by human response to the chemical stimuli (Table 2.1). 

As a consequence of this state of the art, the need and justification for establishing a conventional method for reproducible inertness testing of refill-bottle materials was identified in our laboratory a few years ago. In our opinion, a practical, cost-efficient and relatively quick standard test procedure which could also be used by surveillance labs was worth development. Within an European project (Castle 1997, Jetten et al. 1999), an investigation was undertaken to elucidate the feasibility of such a quick test method for refillable PET bottles, with respect to evaluating their inertness concerning the uptake and subsequent release of chemicals and sensory-active compounds. Before starting method development, the following considerations were made and... 

Derivation of threshold concentrations of sensory-active compounds... 

Enantioselective differentiations of optically and sensorially active compounds point out new possibilities in structure-function relationships and biogenesis of chiral volatiles ]49, 22],... 

In order to further resolve GPC fraction III into distinct sensory active compounds and to rate them in their relative taste impacts, this fraction was then separated by RP-HPLC (Figure 2) into 16 subfractions. Application of the comparative taste dilution analysis using sucrose as the basic tastant revealed the highest TD factor for sweetness for fraction III-5, thus indicating the presence of a sweetness enhancing compound in that fraction. 

Another important group of reactions are those in which the hydrocarbon chain of the alkoxyl radicals cleaves to form low molecular weight products, mainly volatile and sensory active compounds. The cleavage takes place on both sides of the alkoxyl radicals (Figure 3.45). The composition of reaction products formed from alkoxyl radicals derived from unsaturated fatty acids depends on which carbon, next to the hydroperoxide group, the double bond is located. In addition to non-volatile oxoacids and hydroxy acids. 

The benzodiazepines are probably the most clinically important class of GABA-active compounds. Benzodiazepines modify affective responses to sensory perceptions specifically, they render individuals less responsive to anxiety-producing stimuli and therefore exert a strong anxiolytic action. In addition, benzodiazepines exert sedating, anticonvulsant, and muscle relaxant effects. 

Nitz, S., Kollmannsberger, H., Drawer , F. (1989) Determination of sensorial active trace compounds by multidimensional gas chromatography combined with different enrichment techniques. f Chromatogr. 471 173-185. 

Trace compounds without any sensorial relevance (odour activity value much less than 1) should not be evaluated in the sense of authenticity assessment, as the fraudulent addition of a sensorially ineffective compound makes no sense. 

Measuring the content of primary oxidation products is limited due to the transitory nature of peroxides. Yet, their presence may indicate a potential for later formation of sensorially objectionable compounds. The peroxide content increases only when the rate of peroxide formation exceeds that of its destruction. In cases where peroxide breakdown is as fast as or faster than peroxide formation, monitoring lipid peroxides is not a good indicator of oxidation. This can occur in frying oils and sometimes in meat products, particularly in cooked meats where iron is very active and peroxide breakdown is quite rapid. Because the acceptability of an oil or lipid-containing food product depends on the degree to which oxidation has progressed, the simultaneous detection of primary and secondary lipid oxidation products helps to better characterize lipid quality. It is... 

EXTENSIONS AND COMMENTARY Why would there be interest in this particular compound The track record from the comparison of active compounds that are primary amines, and their N-methyl homologues, has shown that, in general, the stimulant component might be maintained, but the psychedelic contribution is generally much reduced. MDMA is, of course, an exception, but then, that particular compound is a one-of-a-kind thing which simply defies all the rules anyway, and I drop it from this kind of reasoning. And as 4-MA is a pretty pushy stimulant with little if any sensory sparkle, why bother with the N-methyl compound at all ... 

Materials science associated with fracture mechanics has mainly been confined to composite materials such as concrete, ceramics and metals. Much of the emphasis of the research has been on preventing fatigue and failure rather than designing for it to occur. The way a structure deforms and breaks under stress is crucial for properties such as flow and fracture behaviour, sensory perception of structure, water release and the mobility and release of active compounds. In the case of foods, the ability to break down and interact with the mouth surfaces provides texture and taste attributes. The crack propagation in a complex supramolecular structure is highly dependent on the continuous matrix, interfacial properties and defects and the heterogeneity of the structure. Previous structure-fracture work has dealt with cellular plant foods, and it has been demonstrated that the fracture path differs between fresh and boiled carrots due to cellular adhesion and cell wall strength as well as cell wall porosity and fluid transport (Thiel and Donald 1998 Stoke and Donald 2000 Lillford 2000). 

In wines, peptides are the least known nitrogen compounds, in spite of the fact that they are involved in diverse properties such as tensioactivity (Gonzalez-Llano et al. 2004), sensorial activity (Desportes et al. 2001) and antihypertensive activity (Pozo-Bay6n et al. 2005), among others. Also they can act as nutrients for yeasts... 

Cabernet wine comparison. One of the objectives of the study was to identify the odoi active compounds of wines with "Brett" flavor through sensory analysis and gas chromatography-olfactometry (GCO). Wines identified by their respective winemakers as having "Brett" character were evaluated by a trained expert sensory panel also, using the technique CharmAnalysis (92-94) for GCO analysis, along with gas chromatography-mass spectrometry (GC-MS), odor-active compounds were identified by their respective Kovats retention indices (95). Contained below is a... 

Table 5 shows the sensory evaluation by Schieberle et al. (30) of the different kinds of butter, namely, Irish sour cream (ISC), cultured butter (CB), sour cream (SC), sweet cream (SwC), and farmer sour cream (ESC). It revealed ISC butter and ESC butter with the highest overall odor intensities. Table 5 shows that 19 odor-active compounds were detected by aroma extract dilution analysis (AEDA) in a distillate of the ISC butter. The highest flavor dilution (ED) factors have been found for 5-decalactone, skatole, i-6-dodeceno-y-lactone, and diacetyl followed by trany-2-nonenal, cw,c -3,6-nonadienal, c/i-2-nonenal, and l-octen-3-one. 

Gas chromatography-olfactometery (GC-O) provides a sensory profile of odor active compounds present in an aroma extract by sniffing the GC effluent. Several techniques have been developed to collect and process GC-O data and to estimate the sensory contribution of individual odor active compounds, including dilution analysis (29, 30), time intensity (31), and detection frequency (32) methods. GC-O has successfully been used to evaluate the odor active compounds of olive oil (33), soybean oil (34), and fish oil enriched mayonnaise (35). 

Process flavourings are more related to cooking than to chemical synthesis. The reactions that occur are chemically very complex with hundreds of volatiles and nonvolatiles being formed. The final process flavouring is defined by the sum of the sensory effects of all aroma-active volatiles and taste-active compounds. 

Finally, regarding the 12-13 s-type sensilla, electrophysiological recordings are scarce. Hiroi et al. (2002) reported responses to sucrose and other sugars from a few sensilla, but obviously the range of activating compounds for the four gustatory sensory neurons in these sensilla still needs to be examined in more detail. 

Although there has been much study of the relationship between the structure and the sensory activity of odorous molecules, it frequently appears impossible to predict the odour from its chemical structure. In other words, very similar chemical structures can have quite different smells (e.g. the para versus the meta form, optical isomers). Contrarily, different compounds in terms of functional group, shape, etc can have similar smells [2]. 

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