Organoleptic purity

Chemical purity and organoleptic purity are not synonymous. For example, the aldehyde (Structure 1) was discovered when a sample of the alcohol (Structure 2) was found to have the expected muguet (lily of the valley) odor (21). The alcohol was prepared from 4-f-amylcyclohexanone (Structure 3) by the scheme shown in Fig. 2. The reduction product contained mostly the desired alcohol (Structure 2) but with some of the isomeric material (Structure 4) in which the double bond had moved into the ring. Flowever, gc-sniffing revealed that neither of these was responsible for the muguet odor of the sample, but rather that it was caused entirely by a tiny trace of aldehyde (Structure 1). Unless organoleptic purity is verified by such techniques, a risk of mistaken attribution of an odor... 

Sample purity is always important when measuring properties for SAR work. In the field of olfaction, the organoleptic purity (i.e. odour purity) is even more important than chemical purity, especially when measuring odour character. A small trace of an impurity with a very intense odour is likely to lead to incorrect results in the odour measurement and thus render the data, and hence any resultant SAR, invalid. For example, 1 ppm of thiomethanol will distort the odour of geraniol far more than would 10% of citronellol. Therefore any SAR on odour will be suspect if the data originates from a source which is unfamiliar with measurement of organoleptic purity. 

Genuine chemical methods were preceded by techniques such as the touchstone,26 and also by the direct investigation of the material or object by the use of the senses. A material could be felt, it could be tasted, its colour could be observed, it could be smelt, and the noise it could be induced to make could be listened to. The use of such methods of organoleptic analysis in the work of the Georgian King, Vakhtang VI (1675-1737) have been described.27 Probably the first demand for a quantitative analytical method arose from a desire to estimate the purity of samples of gold. While... 

Vanilla essence comes in two forms the actual extract of the seedpods and the far cheaper synthetic essence, basically consisting of a solution of synthetic vanillin in ethanol. Natural vanilla is an extremely complicated mixture of several hundred different compounds, versus synthetic vanillin which is derived from phenol and is of high purity. Many commercial vanilla extracts are now actually blends of natural and synthetic vanillin. The occurrence of several non-vanillin aroma and flavour components in minor or trace amounts in beans is the reason for their organoleptic superiority over synthetic vanilla and blends. Natural vanilla has a delicate, rich and mellow aroma and aftertaste, while the synthetic material is quite heavy, grassy and less pleasant. 

These higher purity slips are characterized by lower organoleptics, or taste and odor components. A company recently introduced a low organoleptic erucamide slip product called Incroslip that has advantages for the bottled water and beer industries. 

The thorough study of essential oils is based on the relationship between their physical and chemical properties and is completed by the assessment of organoleptic qualities. The earliest analytical methods applied in the investigation of an essential oil were commonly focused on quality aspects, concerning mainly two properties identity and purity [17]. 

Oxidation of beta acids is a vast field yielding dozens of compounds all of which have been discussed in this book. LC analysis of the mixtures from which they were isolated, their purity check, establishing their capacity ratios and searching for them in beer would all be most important and interesting. In this context, the lupoxes, lupdols and lupdeps come to mind since they were isolated from beer. Their organoleptic evaluation, once LC proves purity, should be carried out in the best conditions possible to further the search for the origin of harsh bitterness of some beers. 

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