Christian E. Butzke

Analysis of 2,4,6-trichloroanisole in wines using solid-phase microextraction coupled to gas chromatography-mass spectrometry.

Cork taint in wine is a serious problem which is exacerbated by the difficulty of its assessment. Current analytical procedures are costly, time consuming and require the use of large amounts of solvents. We developed and evaluated a rapid method for the detection of the cork taint compound, 2,4,6-trichloroanisole (TCA), in wine samples. The method employs solid-phase microextraction, a solventless, automated sampling procedure, coupled to GC-MS-selected ion monitoring analysis. Quantification is enabled by a fully deuterated [2H5]TCA analog used as an internal standard. Accuracy (+/- 8%), precision (R.S.D. 5-13%), and limit of quantification (5 ng/l) are comparable to existing methods.

Analysis of brandy aroma by solid-phase microextraction and liquid–liquid extraction

Headspace solid-phase microextraction (SPME) and continuous liquid–liquid extraction (LLX) with Freon were used to extract and analyse aroma volatiles in brandy. In general, SPME using a non-polar polydimethylsiloxane coating was more selective for esters and acids than was LLX. LLX using Freon 11 extracted the higher alcohols more efficiently than SPME. Relative differences in volatiles between brandies made from Vitis vinifera L cv Colombard and Vitis vinifera L cv Ugni blanc were observed, particularly for hexanol, 3-methylbutylacetate, 3-methylbutanol and 3-methylbutyloctanoate. In addition, a combination of SPME with GC–olfactometry was used to provide more detailed information on sensory characteristics of varietal brandies. © 2000 Society of Chemical Industry

The characterisation of a novel Pichia anomala β-glucosidase with potentially aroma-enhancing capabilities in wine

The production and characterisation of β-glucosidase from an isolated yeast strain classified as aPichia anomala MDD24 were studied. The result shows that cellobiose is a good inducer for extracellular β-glucosidase production and optimum concentration is 1.5 percent cellobiose in yeast peptone dextrose medium. The purified β-glucosidase fromPichia anomala MDD24 exhibited a specific activity of 614±14 U mg−1 of protein and a molecular mass of 42 kDa. This enzyme was slightly inhibited by fructose and sucrose in the range of 4 to 20% (w/v). An ethanol concentration between 4 and 20% (v/v) activated β-glucosidase activity, at presence 16% (v/v) ethanol, β-glucosidases obtained maximum relative activity around 150%. The optimum pH and optimum temperature for β-glucosidase activity were 4.5 and 40 °C, respectively. Although the activity under the pH and temperature of wine production (pH 3.5–4.0 and 15–20 °C) was quite low, the enzyme was stable and the relative activities were higher than commercial enzyme under those conditions. The extracellular β-glucosidase fromPichia anomala MDD24 makes it possible to release glucosidically-bound monoterpenes, which are the major contributors to floral and fruity aromas in wines fromMuscat-type varieties, at final stage of alcoholic fermentation.

Effects of heat exposure on wine quality during transport and storage

The exposure of wine to elevated temperatures has a profound impact on its aging reactions and its sensory quality, shelf life and healthfulness. This study monitored the exposure of wine to heat during commercial shipments through the national distribution chain from wineries to wholesalers across the USA under extreme but realistic conditions. The results document the exposure of wine shipments in regular non-refrigerated containers with different types of external and internal insulation. During the months of summer and early autumn, wines shipped to or via hot geographic locations were frequently exposed to temperatures above 24°C and often for extended periods of time. Under the most extreme shipping conditions, wines would have been exposed to temperatures of up to 44°C. Notable diurnal fluctuations (4–21°C) were observed. The accumulated heat exposure of the wines was calculated using ethyl carbamate formation as a wine quality indicator and different kinetic models for wine aging were applied to make a comparison with wine storage under empirically ideal cellar conditions. These calculations suggest that some wines were exposed to heat during transport that corresponded to an added bottle age between 1 and 18 months when compared with conventional cellar storage.