: Ester concentrations in the headspace inÑuence the aroma character of alcoholic drinks. Activity coefficients for esters showed log-linear decreases as ethanol concentration was increased from 17% (v/v), with rates inversely related to ester acid chain length. At concentrations below 17% (v/v) the activity coefficient remained constant. This could be related to structural changes in ethanol/ water mixtures. Below 17% (v/v), ethanol forms a monodispersed aqueous solution. Above 17% (v/v), ethanol molecules cluster to reduce hydrophobic hydration and esters partition into these ethanol-rich clusters, where the lower ester interfacial tension reduces the free energy of mixing and hence the activity coefficient. The increased solubility of the ester reduced the headspace concentration of the esters, and hence total ester content may not be a good indicator of their Ñavour impact.1998 SCI. ( Sci Food Agric 77, 121È126 (1998) J

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Thirty samples of virgin olive oil were analysed by sensory and instrumental methods. Free-choice profiling and quantitative descriptive analysis were used for odour analysis, and GC-MS for the analysis of headspace volatiles. Principal component analysis and partial least squares regression analysis were used for relating sensory and instrumental data. Similar clusters of samples were obtained from principal components analyses of both data sets. Partial least squares regression made good predictions from headspace data of some of the descriptors used in quantitative descriptive analysis. The prediction of cut grass odour was obtained in particular from five unidentified compounds. The five compounds had similar mass spectra, but GC-sniffport analysis showed that only one of them (possibly isomers or homologues) gave an aroma that could be related to the cut grass descriptor.

Cask staves, prepared from American white oak, Quercus alba, were obtained from unused, new charred Bourbon, used Bourbon, first-fill Scotch and exhausted Scotch casks. The aim of the experiment was to determine the effect of repeated maturations of whisky on concentration and location of phenolic extractives in the cask wood. Contents of vanillic and syringic acids and the respective aldehydes, arising from hydrolysis of guaiacyl-syringyl lignin, and whisky lactones (cis-and trans-8-methyl-y-octalactone), arising from charring, were determined. Staves were sampled at 5 mm intervals from the inner char surface to 25 mm depth and wood extracted with chloroform, heptane and aqueous ethanol. Contents of material absorbing at 520 nm, total phenols and vanillic and syringic acids, vanillin and syringaldehyde, were determined by highperformance liquid chromatography ; both isomers of whisky lactone were quantified by high-resolution gas chromatography. New cask wood had a maximum for coloured material in the char layer, but maxima for other compounds at 5mm below the char. As casks were reused in maturations of whiskies, the contents of aromatic aldehydes and acids were reduced in the first 20 mm of the wood and maxima for both acids and aldehydes shifted towards the centre of the staves. This suggested that repeated exposure to aqueous ethanol resulted in compositional changes in the lignin in the wood. The newly charred wood had a maximum for cis-8-methyl-y-octalactone at 5 mm below the char and the trans isomer at 15 mm. In the first Bourbon maturation both isomers were largely depleted and with successive extractions the maxima moved into the cask until in the exhausted cask wood no lactone was detected.