Damascenones

Of all these, probably P-phenethyl alcohol (2) comes closest to the odor of fresh rose petals however, mixing all these components does not reproduce the total fine character of the natural oil. It has been determined that a number of trace constituents representing less than 1% of the volatiles are critical to the development of the complete rose fragrance (10). These include cis- and trans-i.ose oxide (1), nerol oxide (12), rose furan (13), /)i7n7-menth-l-en-9-al (14), P-ionone (15), P-damascone (16), and P-damascenone (3). 

Rose. Rose is one of the most important florals ia perfumery, the most valuable derivatives of which are produced from Rosa damascena, which is grown principally ia Bulgaria, but also ia Russia, Turkey, Syria, India, and Morocco. The concrete, absolute, and steam-distilled essential oil (rose otto) are particularly valuable perfume iagredients. Careful handling and processiag of freshly picked flowers are required to produce these materials of warm, deeply floral, and rich odor quaUty. They are complex mixtures of which citroneUol (9), geraniol (8), phenethyl alcohol [60-12-8] (21), and P-damascenone [23726-93 ] (22) (trace component) are important odor constituents. 

Scheme 4.46 Synthesis of glucosidic damascenone by the Stg2 reduction.

In contrast to the rather simple cases of wintergreen and grape aromas, that for roses is complex. Rose oil contains at least 275 chemical constituents, of which citronellol is the major one. However, two of the minor constituents make the major contribution to rose aroma—p-damascenone and P-ionone ... 

Of the 400 volatiles detected in the tomato, only 17 have a positive impact on the flavor profile. Two of the most important ones are also key players in the aroma of roses p-ionone and p-damascenone. Another player is methyl salicylate, a compound we previously encountered in oil of wintergreen. Some of the most important flavor elements are present in very small concentrations but can be perceived by us at these extremely small concentrations. 

In addition to the major components mentioned above, rose oil also contains a number of components which, although present in low concentrations, contribute to the characteristic fragrance [725-73 lb]. Among these are /3-damascenone (see p. 68) and rose oxide (see p. 143). 

Ethyl 2-methylbutanoate, 2-methylbutyl acetate and hexyl acetate contribute most to the characteristic aroma of Fuji apples [49]. In Red Delicious apples, ethyl butanoate, ethyl 2-methylbutanoate, propyl 2-methylbutanoate and hexyl acetate contribute to the characteristic aroma as determined by Charm-Analysis and/or AEDA [50, 51]. In a comparative study of 40 apple cultivars, the highest odour potency or Charm value was found for -damascenone [52]. This compound usually occurs in a glycosidically bound form and is present primarily in processed products owing to hydrolysis of the glycoside bond after crushing fruit cells [53]. -Damascenone has a very low odour threshold with a sweet, fruity, perfumery odour and is not typical of apple aroma in gen-... 

Important aroma compounds of black currant berries have been identified mainly by GC-O techniques by Latrasse et al. [119], Mikkelsen and Poll [115] and Varming et al. [7] and those of black currant nectar and juice by Iversen et al. [113]. The most important volatile compounds for black currant berry and juice aroma include esters such as 2-methylbutyl acetate, methyl butanoate, ethyl butanoate and ethyl hexanoate with fruity and sweet notes, nonanal, /I-damascenone and several monoterpenes (a-pinene, 1,8-cineole, linalool, ter-pinen-4-ol and a-terpineol) as well as aliphatic ketones (e.g. l-octen-3-one) and sulfur compounds such as 4-methoxy-2-methyl-butanethiol (Table 7.3, Figs. 7.3, 7.4, 7.6). 4-Methoxy-2-methylbutanethiol has a characteristic catty note and is very important to blackcurrant flavour [119]. 

The characteristic elderberry odour has been shown to be correlated to -damascenone, dihydroedulan and ethyl 9-decenoate with elderberry-like notes, and to some extent also to 2-phenylethanol, phenylacetaldehyde and nonanal with elderflower-like notes [127,128,130,131] however, only nonanal. 

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