Coconut aroma

Among the many volatile substances released by wood in wine, volatile phenols, /S-methyl-y-octalactones and phenol aldehydes are the principal compounds responsible for the wood aroma of barrel-aged wines. Volatile phenols, in particular eugenol, give wine smoky and spicy aromas. Cis-and fran.y-methyl-y-octalactones are responsible for the coconut aroma. Volatile phenols, essentially vanillin, produce vanilla notes. Furanic aldehydes have grilled aromas but their perception threshold is much higher than concentrations found in wine. Their olfactory impact is thus negligible. 

Twenty-nine odour-active compounds were detected by using aroma extract dilution analysis (AEDA) [60]. The results of AEDA together with GC-MS analysis showed ethyl 2-methylbutanoate (described as fruity flavour), followed by methyl 2-methylbutanoate and 3-methylbutanoate (fruity, apple-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (sweet, pineapple-like, caramel-like), d-decalactone (sweet, coconut-like), l-( ,Z)-3,5-undecatriene (fresh, pineapple-like), and a unknown compound (fruity, pineapple-like) as the most odour-active compounds. 

The closely related 5-decanolide (5-decalactone), not only found in many fruits but also found in dairy products, exhibits a creamy-coconut, peach-like aroma [49] and can be synthesised from the corresponding a,(3-unsaturated lactone 2-decen-5-olide found in concentrations of up to 80% in Massoi bark oil using basidiomycetes or baker s yeast [229]. After about 16 h of fermentation, 1.2 g 5-decanolide was obtained. At the same time, the minor lactone in... 

In addition, y-nonalactone 4, (S)-(-)- and (R)-(+)-4-pentylbutan-4-olide, shows weak to strong sweet coconut notes, as well as peach and apricot aromas. 

There is increasing evidence that the interaction of lipids with the Maillard reaction is relevant to the generation of flavor in many cooked foods. For instance, the removal of lipids from coconut has been shown to cause flavor changes in the roast material (12). Uncooked coconut contained significant amounts of lactones as the main aroma components on roasting pyrazines, pyrroles and furans were also found in the aroma volatiles which added a strong nut-like aroma to the sweet aroma of the unroasted coconut. When ground coconut was defatted and then roasted, the sweet aroma due to lactones disappeared and the product possessed a burnt, nut-like aroma. A marked increase in the number and amount of Maillard reaction products, in particular pyrazines, was found. 

Lactones are cyclic compounds formed through the intramolecular esterification of a hydroxy fatty acid. 7-Lactones and 8-lactones, with fivesided and six-sided rings, respectively have been found in cheese (Jolly and Kosikowski, 1975 Wong et al., 1975 Collins et al., 2004). The origin of the precursor hydroxy fatty acids has been ascribed to a 8-oxidation system in the mammary gland of ruminants (see Fox et al., 2000), the reduction of keto acids (Wong et al., 1975) and/or the action of lipoxygenases and other enzymes present in members of the rumen microflora (Dufosse et al., 1994). Lactones have low flavor thresholds and while their aromas are not specifically cheese-like (their aromas have been described variously as peach, apricot and coconut ), they may contribute to the overall flavor of cheese (see Collins et al., 2004). 

The two oak lactone isomers cis- and fran -p-methyl-y-octalactone) were first identified in oak wood by Masuda and Nishimura (1971). They are one of the main volatile components present in the extractible fraction of oak wood. Smdies have revealed the detection thresholds for these two isomers to be 0.092mg/L for the cis isomer and 0.49mg/L for the trans isomer in white wines (Chatonnet 1991). Their aroma has been identified as the source of the typical odour of oak barrel aging and has been described as oak or coconut . 

Whereas the glucose ester 9 has been identified for the first time as a natural wine constituent, glycoconjugates of its reduced form, i.e. of the monoterpene diol 11, are known Riesling wine constituents (2). Under acidic conditions, diol 11 was partially converted into the bicyclic ether 12, the so-called dillether (2). In analogy to the formation of ether 12 from terpene diol 11, a likely formation of lactone 10 from acid 9A could be be expected (cf. Fig. 5). This so-called wine-lactone 10, first identified as an essential oil metabolite in the Koala (55), has recently been established by Guth (34) as a major aroma contributor in two white wine varieties. The 35,3a5,7aR-configured isomer of 10, which has been identified in wine, is reported to possess an unusual low flavor threshold of 0.01-0.04 pg/L of air and a sweet, coconut-like aroma (55). 

In this context it should be mentioned that y-lactones do not occur as genuine constituents of coconuts [83], Thus, it seems to be rather clear, that aroma-relevant amounts of y-lactones in coconut products are of non-natural origin and there is no reason to look for their stereoanalysis in the low ppb-range [82],... 

A fungus widely distributed in the soil, Trichoderma viride, produces an interesting compound with a coconut, peachy aroma in a non-agitated liquid medium containing potato extract and salts(52). After three to four days cultivation, the culture sporulates releasing the metabolite 6-pentyl-alpha-pyrone. The maximum level reported, however, is 0.17 gram/L. 

C9Hi602, Mr 156.22, pi.7kpa 136 °C, c%° 0.9676, H50 1.446, occurs in many foods and is a pale yellow liquid with a coconut-like aroma. It has numerous applications, similar to those of y-octalactone, in aroma compositions and perfumery. 

Ci0Hi8O2, Mr 170.25, bp3 Pa 117-120°C, r/f 5 0.9540, ng 1.4537, is a flavor constituent of many types of fruit, cheese, and other dairy products. It is a colorless, viscous liquid with a creamy-coconut, peach-like aroma. 

Benzothiazole is a colourless liquid, bp 227°C, sparingly soluble in water. It is an aroma constituent of cocoa beans, coconuts, walnuts and beer. 

Sn-beta, combined with hydrogen peroxide as oxidant, has the potential to substitute classical oxidants, for example peracids, in BV oxidations. As an example, the oxidation of delfone (2 pentylcyclopentanone) to d-decalactone (tetrahydro-6-pentyl-2H-pyran-2-one) is currently achieved using the corrosive peracetic acid. The resultant lactones have a creamy coconut-and peach-like aroma and are important flavor constituents of many types of fruit, and cheese and other dairy products. The lactones are also used in fragrances the two enantiomers have different aromas. Sn-beta was tested for this BV transformation in a stirred reactor. The desired lactone product was obtained in 86% yield in the presence of the Sn-beta catalyst. (302) This result demonstrated clearly that the combination of Sn-beta and hydrogen peroxide is an environmentally friendly alternative to the commonly used organic peracids, even in asymmetric synthesis. Instead of a stoichiometric amount of carboxyHc acid waste, water is produced as a side product from the oxidant. 

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