Odoriferous components

Many cycHc ketones occur in natural oils. Jasmone [488-10-8] (3-meth5l-2-(2-pentyl)-2-cyclopenten-l-one) (4) is an odoriferous component of the oil obtained from jasmine flowers. /-Menthone [14073-97-3] (5) is the most frequently occurring of four optically active isomers, and is a colorless Hquid with a minty odor obtained from Mentha species of plants. Muscone [541-91-3] (6) and civetone [542-46-1] (7) are expensive animal products. 

Pinaceae needle oils from Pinaceae species contain (—)-bornyl acetate as their main odoriferous component. Other main constituents are monoterpene hydrocarbons such as a- and /3-pinene, limonene, 3-carene, and a- and /3-phellandrene [713-718b]. The oils are used in perfumes for soap, bath products, and air fresheners and in pharmaceutical preparations. 

In one of the experiments in this chapter, you isolate the naturally occurring fat trimyristin from nutmeg, a valuable spice. In other experiments in this textbook, you have the opportunity to isolate citral, the odoriferous component of lemongrass oil (Sec. 4.6), and to separate different pigments found in green leaves (Sec. 6.2). You may also examine the two enantiomers of carvone, one of which is found in spearmint and the other in caraway seed oil (Sec. 7.4). The techniques you will use in these experiments serve as an introduction to the methods that are used in research laboratories to isolate natural products having potential value to society. 

Flavors are never attributed to a single aroma compound rather, foods are flavored by multitudes of odoriferous components frequently present in trace concentrations. Thus, for instance, the volatile components of fruits only rarely exceed a quantity of 10 ppm (441) (Table 1). The isolation of the original aroma without any substantial modification requires special methods which have to be adapted with great care to the specific food 472). Some cases are known where a natural flavor impression is dominated by one single substance (character impact compound) (270) (Table 2) or a small number of compounds mostly of... 

Cedarwood oil Atlas contains as its major odoriferous components a- and y-atlantone. Other constituents include acetone, a-ionone, and a-caryophyllene, among others. 

The number of synthetically produced fragrance and flavor chemicals has since expanded continually as a result of the systematic investigation of essential oils and fragrance complexes for odoriferous compounds. Initially, only major components were isolated from natural products their structure was then elucidated and processes were developed for their isolation or synthesis. With the development of modern analytical techniques, however, it became possible to isolate and identify... 

In subsequent studies the simple terpenes EJi-a- and -/3-farnesene (3 8 and 39, respectively) were identified in dominant male urine.128 These odoriferous terpenes had long been recognized as components of cues released by a variety of other organisms (red fire ants, aphids, wild potato plants, fruit flies, and springbok). Because neither was detected in male bladder urine, attention was focused on the preputial glands as the source. Volatile components from dissected, fat-free preputial glands of dominant male mice were, again, preconcentrated on Ten ax. Subsequent GC analysis readily allowed identification of known 37 and 38. None of the earlier two components 36 or 37 was observed in the preputial volatiles, but both were present in the bladder urine of the same animals. 

Males of neotropical euglossine bees (Apidae), called orchid bees, collect odoriferous substances from flowers of orchids and other plants. The floral scents of these species display relatively simple chemical compositions dominated by one or two major components, mostly terpenoids and aromatic compounds such as cr-pinene, 1,8-cineol, eugenol, -dimethoxybenzene (35), 2,3-epoxygeranyl acetate (36), nerolidol, 4-methoxycinnamaldehyde (37), and benzyl benzoate.113 Since the orchid bees have odor preferences, their collection of fragrances leads to specialized pollination of particular plant species. Male bees absorb the floral volatiles with their tarsal hairs, form species-specific bouquets, and finally accumulate them in their hind tibial pouches. These bouquets have potential roles in courtship displays and marking territories.114 115... 

Deodorization. The neutralized/bleached oil is pumped into a deaerator operated under a pressure of 500 Pa to evacuate entrained air. From the deaerator, the oil passes through a shell and tube economizer and is heated to a temperature of 240°C by means of a thermal oil heater. The stripper and deodorizing column operates under a pressure of 600-1000 Pa volatile components such as low-molecular-weight fatty acids, ketones, aldehydes, and other odoriferous substances are stripped off by live steam. The rising vapors laden with volatile components pass through a cyclone scrubber where fresh fatty acid oil is sprayed on top of the vessel to recover outgoing fatty acids. 

Choline, supplied as dietary PC or as free choline, is required in the diet by rats. Although it has not been established that choline is required by humans, it is probably an essential nutrient and may, in the future, be classified as an essential amine or vitamin, Its possible requirement is a concern to clinicians feeding patients by total parenteral nutrition (TpN), In this type of feeding, which may be used for a year or longer, the patient is sustained intravenously with an artificial, chemically defined diet. The choline in foods occurs mainly as PC rather than as free choline. PC is a more desirable dietary component because, when free choline is consumed in large amounts, it is degraded by the gut bacteria to produce trimethylamine, an odoriferous compound (Magil et ai, 1981). 

The first molecule found to be a characteristic component of the aroma of Sauvignon Blanc wines was 4-mercapto-4-methyl-pentan-2-one (Figure 7.9a) (Darriet et al., 1993 Darriet, 1993 Darriet et al., 1995). This extremely odoriferous mercaptopentanone has a marked smell of... 

In the presence of sodium cthoxide, these dienoic acids can be isomerized in high yield to conjugated 2,4-dienoic acids. Surprisingly 6 is isomerized to a mixture of the (2E, 4Z)- and the (2E, 4E)-isomers in a 2 1 ratio. This mixture can be equilibrated mainly to the more stable (2E, 4E)-isomer (867o) by treatment with Ihiophenol in the presence of AIBN (6, 585-586). The ethyl (2E, 4Z)-decadienoate obtained by rearrangement of 6 is a component of the odoriferous principle of Bartlett pears. 

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