Fragrance components

Table 4.2 Selected floral fragrance components of Cypripedium (top panel) and classes of compounds (bottom panel) (after Bergstrom et al., 1992)...

In this equation x, is the liquid perfume concentration, Mt the molecular weight, R the ideal gas constant, and T the absolute temperature. Equation 2 relates the liquid perfume composition, x, with the human sensory reaction of the evaporated perfume. A key factor of Equation 2 is the activity coefficient, y, because it represents the affinity of a molecule to its neighboring medium. High value of y means an increased inclination for a given substance to be released from the mixture and low value of y means a low concentration in the headspace. This means that the OV values of a particular component can change if it is diluted in different solvents or mixed with different fragrance components. 

Jeff Quigg says the mixing of a perfume is "a trial and error process." An experienced perfumer must memorize a vast library of hundreds or even thousands of individual scents and combinations of scents. Perfume ingredients can be divided into natural essential oils (derived directly from plants) and aromatic chemicals (synthetically produced fragrance components). 

Very metallic fragrance, agressive, not sweet as (S) and (Ff) citronellol, rosis fragrance component is almost fully... 

Hills, H. G. (1989). Fragrance cycling in Stanhopea pulla (Orchidaceae, Stanhopeinae) and identification of trans-limonene oxide as a major fragrance component. Lindleyana 4 61-67. 

Safety Aspects in Handling and Exposure. Pyridine compounds are ubiquitous in the natural environment, and are often found in foods as minor flavor and fragrance components. Some synthetic pyridines are used as food additives. A high proportion of pyridine compounds shows some type of bioactivity, albeit mostly minor, such as herbiddal, insecticidal, or medicinal activity. Therefore, all the normal precautions should be exercised when handling pyridines that would be used when handling other organic products that are potentially bioactive. 

Another example employed Mitsunobu reaction for the inversion reaction (Figure 10(b)).A single enantiomer of a (stereo)chemically labile allylic-homoallylic alcohol was obtained in 96% yield and 91% ee from the racemate through a lipase-catalyzed kinetic resolution coupled with in situ inversion under carefully controlled (Mitsunobu) conditions. Using this reaction, the algal fragrance component, (S)-dictyoprolene, was synthesized. 

The Linstead variation of the Knoevenagel condensation catalysed by a series of supported guanidines prepared via different routes, was also investigated by us in collaboration with Macquarrie s group, and revealed excellent results. This condensation reaction can be used for the synthesis of the precursor of coconut oil lactone, a fragrance component ( Scheme 9.8).11741... 

Polyunsaturated aliphatic alkohols, aldehydes, ketones, and esters occur as fragrance components in fats, oils, fruits and plants 158). As an example the synthesis of ethyl (2 ,4Z)-2,4-decadienoate (232, pear ester ), which is responsible for the aroma of bartlett pears 161) is given. 2,4-Diunsaturated ester 232 may be obtained by a number of highly stereoselective syntheses, a lot of them making use of the Wittig reaction. Ohloff and Pawlak condensed 4,5-epoxy-( )-2-pentenal 228 with the ylide generated from 229 (butyllithium/ether) to the alkadiene epoxide 230 which was oxidized with periodic acid to the 2,4-decadienal 231. 231 is subsequently converted with MnOj/NaCN in ethanol to the pear ester 232162) [75 % (Z)-amount of the C-4 double bond] (Scheme 44). 

Barbe, A.M., et al. Retention of volatile organic flavor/fragrance components in the concentration of liquid foods by osmotic distillation, J. Membr. Sci., 145, 67, 1998. 

Osmotic distillation is unique among concentration processes in that feeds containing thermally labile or shear-sensitive components, and those with appreciable volatility, can be concentrated with little or no loss of product integrity. This characteristic is particularly important for the concentration of fruit juices and other liquid foodstuffs, such as vegetable juices, and tea and coffee extracts. These feeds contain a complex mixture of essential volatile hydrophilic flavor, and fragrance components in very low concentrations. Substantial depletion of these components by direct destruction or evaporation may render the product... 

Osmotic distillation is a relatively new membrane separation process, which is used primarily for the dewatering of liquid food products. The majority of reported applications have involved the production of fruit juice concentrates. The main advantage of OD over vacuum distillation, which is the conventional method for concentrate production, is the preservation of product integrity. Osmotic distillation is operated at mild temperatures (typically ambient), and thereby produces concentrates that are free from the effects of thermal degradation. Also, the delicate volatile flavor and fragrance components that are essential to consumer acceptance of fruit juice concentrates are largely retained. 

Walker DFG, Bartle KD, Breen DGPA, Clifford AA, Costiou S. Quantitative method for the analysis of flavour and fragrance components from lavender and rosemary for studying the kinetics of their supercritical fluid extraction. Analyst 1994 119 2789-2793. 

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