P-Methyl-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 . 

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)... 

Feuillat, F., Moio, L., Guichard, E., Marinov, M., Fournier, N., and Puech, J.L. (1997). Variation in the concentration of ellagitannins and cis- and trans-p-methyl-y-octalactone extracted from oak wood (Quercus robur L., Quercus petracea Liebl.) under model wine cask conditions, Am. J. Enol. Vitic., 48(4), 509-515. 

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 29 Direct SBSE sampling of volatile flavor components from one whole grape. Peaks are as follows 1, hexanol 2, 2-nonanone 3, furfural 4,5-methylfurfural 5, phenylacetaldehyde 6, y-hexalactone 7, cyclotene 8, y-octalactone, 9, 2-phenylethyl alcohol 10, furaneol , p- and m-cresol 12, norfuraneol 13, y-decalactone 14, 3,5-dihydroxy-6-methyl-2,3-dihydro-pyran-4-one 15, 2-formyl-5-hydroxymeth-ylfuran.

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