Y-Octalactone

Wines are biologically aged in old casks which, unlike those used for vintage aging, are rarely emptied or scrubbed. As a result, biologically aged wines contain minimal amounts of lactones from wood such as p-methyl-y-octalactone (Chaton-net et al. 1990) and only in the scales holding the oldest wine. 

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 . 

FeuiUat, R, Moio, L., Guichard, E., Marinov, M., Fournier, N., Puech, J. L. (1997). Variation in the concentration of ellagitannins and cis- and rrani-/i-methyl-y-octalactone extracted from oak wood (Quercus robur L., Quercus petraea Liebl.) under model wine cask conditions. Am. J. Enol. Vitic., 48, 509-515. 

Masson, E., Baumes, R., Le Guemeve, C., Puech, J. L. (2000a). Identification of a precursor of yS-methyl-y-octalactone in the wood of sessile oak Quercus petraea (Matt.) Liebl.). J. Agric. Eood Chem., 48, 4306 309. 

Otsuka, K. I., Sato, K., Yamashita, T. (1980). Structure of a precursor of (i-methyl-y-octalactone, an aging flavour compound of distilled liquors. J. Fermen. Technol., 58, 395-398. 

Sefton, M. A., Francis, I. L., Pocock, K. R, Williams, P. J. (1993). The influence of natural seasoning on the concentrations of eugenol, vanillin and ciT-tTOns-/l-methyl-y-octalactone extracted from French and American oak wood. Sci. Aliments, 13, 629-643. 

Figure 5. Evolution of (3S,4R) trans (a) and (3S,4S) cis p-methyl-y-octalactone during oak seasoning...

Hydroxy-6-methoxy-2//-benzopyranone cw-P-Methyl-y-octalactone Dihydro-2(3H)furanone (y-butyrolactone)... 

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. 

Finally, oak releases lactones into wine during barrel aging. The cis and trans isomers of 3-methyl-y-octalactone (Figure 2.13) are known as... 

Untreated oak contains a certain number of volatile substances with specific odors (Figure 13.9). As previously described, these lactones, in particular /S-methyl-y-octalactone, with four enantiomers (Figure 13.10), two geometrical isomers and two optical isomers, are produced by the breakdown of complex polymers. The cis(—) isomer has an earthy, rather herbaceous character with... 

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