Odor lactone

Hofmann and Schieberle (1996) suggested hydroxyacetaldehyde and 2,3-butanedione as possible precursors of this odorant lactone. A mechanism of formation (in vin jaune ) has been proposed by Guichard et al. (1998) by transformation of threonine (present in coffee) into 2-oxobutyric acid (which can also be derived from carbohydrates), condensation with acetaldehyde and cyclization. 

Of the 11 compounds which constitute approximately 86% of jasmin volatiles, only benzyl acetate, i7t-jasmone (18), and methyl jasmonate possess the characteristic odor of jasmin. Trace components including i7t-j asrnin lactone [34686-71-0] (20) (0.9%) andmethyl ( /-jasmonate (6) (0.1%) are the key contributors to the jasmin odor. 

Following a report that male P. hybneri were attractive to both sexes [99], males were found to produce a mixture containing the sesquiterpene 6-sesquiphellandrene, (R)- 15-hexadecanolide 114, and methyl (Z)-8-hexade-cenoate [100]. Odors from live males were attractive to adults of both sexes, with males also becoming sexually stimulated. Each component alone had some slight activity, with the 3-component blend being the best attractant in laboratory bioassays. The (S)-enantiomer of the macrolide lactone component was not inhibitory. 

The impact of MOX upon reductive odors was included in the study of McCord (2003) for MOX at 5-10 mL/L/month over 5 months on a Cabernet Sauvignon wine in commercial scale tanks. Lower concentrations of methyl mercaptan and ethyl mercaptan were observed in the oxygenated wines, but no impact was seen upon disulfides, in spite of the suggestion that concentrations of the disulfides could increase due to direct oxidation of sulfides. Dimethyl sulfide concentrations were not affected, except that lower concentrations were seen in wines with added toasted oak staves or segments, with or without MOX. The concentrations of various oak extracted compounds were also measured in this study, with similar levels seen with and without MOX alongside appreciable increases due to the presence of the oak staves or segments in some cases (e.g., lactones and vanillin), oxygenation appeared to enhance aroma extraction. 

CioHigO, Mr 154.25, J20 0.887-0.893, 1.446-1.450, is a colorless liquid with a complex floral, aromatic and fruity odor, and a lactonic undertone. It is not found in nature. 

The lactones are the intramolecular esters of the corresponding hydroxy fatty acids. They contribute to the aroma of butter and various fruits. 15-Pentadeca-nolide is responsible for the musk-like odor of angelica root oil. Of the naturally occurring bicyclic lactones, phthalides are responsible for the odor of celery root oil, and coumarin for woodruff. 

The macrocyclic esters hold a special position among the industrially produced lactone fragrance materials. Like the well-known macrocyclic ketones, they have outstanding odor properties as musks. However, the lactones can be prepared more easily than the ketones, for example, by depolymerization of the corresponding linear polyesters. Since replacement of a methylene unit by oxygen affects the odor of these compounds very little, oxalactones with 15-17-membered rings... 

Major mono- and sesquiterpene hydrocarbons in the oil are (+)-limonene (58-79%) and /3-selinene [17066-67-01], 5-20%. Its typical, long-lasting odor is caused primarily by two lactones, 3-butylphthalide [6066-49-5] and sedanenolide [62006-39-7] (1.5-11%) [328-334]. 

In addition to mating-disruption pheromones, there are a number of naturally occurring, nonpheromonal attractants and repellents. Many are typically used as food additives or in cosmetics or perfumes, and are derived from diverse plant and animal sources. Capsaicin [44], the spicy component of chili peppers, is used in several bird, deer, and rodent repellents. Maple lactone [45], a common food additive and flavoring, is used in traps to attract cockroaches with its stale beer odor. Methyl... 

LACTONE. An inneresler of a carboxylic acid formed by intramolecular reaction of Itydroxylated or halogenerated carboxy lic acids with elimination of water. They occur in nature as odor-bearing components of various plant products, also made synthetically. 

It should be stressed that it is a prerequisite of successful flavor precursor studies that the contribution of the odorant under investigation to a food flavor or off-flavor has been established. Sometimes the structure of a precursor can be assumed on the basis of structural elements in the odorant. In such cases, additions of the respective isotope-labelled precursor to the food system is commonly used to elucidate the precursor and to clarify reaction pathways governing the formation of the odorant. This method has been frequently applied, especially, in studies on the enzymatic generation of odor-active aldehydes (e.g., (Z)-3-hexenal in tea leaves) or alcohols (e.g., l-octen-3-oI in mushrooms) [cf. reviews in 84, 85] as well as lactones [86] from unsaturated fatty acids. 

From the wine aromas of Pollux, Castor, and Riesling grapes, Rapp et al. and Schreier and Paroschy have isolated an undesirable strawberry aroma by GC-MS (80V13, 81MI112). This lactone was characterized as 2,5-dimethyl-4-hydroxy-2,3-dihydro-3-furanone 8 ("furaneol") having an odor threshold of 50-100 ppb. 

Numerous y- and 8-lactones were identified in Tokaji aszu grapes (Miklosy and Kerenyi, 2004 Miklosy et al., 2004). The odor notes of the y-lactones were described as resin- and caramel-like, roasted, or honey, while the 8-lactones exhibited characteristic notes of coconut, chocolate, and peach. The same lactones had been identified earlier from botrytized wines but not from normal wines (Schreier et al., 1976). Lactones are mostly found in oxidatively aged wines but seem to develop in fruit due to the oxidizing effect of B. cinerea, water loss, or Maillard reactions (Miklosy et al., 2004). 

The main aroma compounds identified as specific botrytized odorants are indicated in Table 6.6. It seems that while the terpene content decreases, numerous hydroxy-, oxo-, and dicarboxylic acid esters, acetals, and lactones form, all typically in lower concentrations or absent in normal wines (Miklosy and Kerenyi, 2004 Miklosy et al., 2000, 2004 Schreier et al, 1976). 

In a more recent study, Bailly et al. (2009) investigated the stability of key odorants during bottle aging in Sautemes wines. Except for 3SH, polyfunctional thiols were found unstable. However, most other key odorants (e.g., sotolon, phenylethanol, esters, y-lactones, p-damascenone, etc.) were still detected within 5-6 years. 

The nature of the Botrytis aroma compounds has been subjected to extensive research. In addition to the older findings about the importance of hydroxy-, oxo-, and dicarboxylic acid esters, acetals, and some special y- and 8-lactones, the role of volatile thiols has recently been elucidated. Nonetheless, additional research is needed to identify odor active compounds that are specific for botrytized wines. 

The powerful potentialities of SBSE followed by thermal desorption and GC-qMS methodology to characterize Madeira wine was also explored by Perestrelo et al. (2009). This methodology provided higher ability for profiling traces and ultratraces of compounds in Madeira wines, including esters (80.7-89.7%), higher alcohols (3.5-8.2%), Ci3 nor-isoprenoids (1.7-6.5%), carboxylic acids (1.6H-.2%), aldehydes (0.9-3.7%) pyrans (0.2-1.7%), lactones (0.3-2.7%), and mono (0.1-1.4%), and sesqui-terpenoids (0.1-0.8%). The authors reported that the concentration of some of them is above their odor threshold, and therefore can probably play a remarkable impact on the aroma complexity of the corresponding wines. 

A model wheat bread was prepared by a straight dough procedure from wheat flour, salt and water using glucono-delta-lactone as leavening agent (Schieberle, P., in preparation). The bread crust showed an odor note reminiscent of day-old bread and, specifically the cracker-like, roast odor note was lacking. 

Figure 7-25 Flavor Character of Some Lactones. Source From R. Teranishi, Odor and Molecular Structure, in Gustation and Olfaction, G. Ohloff and A.F. Thomas, eds., 1971, Academic Press.

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