The contribution of wood to the flavor of alcoholic beverages

112

Background and Aims: The chemical composition and sensory properties of smoke-affected grapes and wine has been the subject of several recent studies. However, while this research has addressed early knowledge gaps surrounding the effect of smoke on grapes and wine, to date, no practical solutions that mitigate the incidence or severity of smoke taint have been reported. The current project therefore aimed to identify winery processing methods that minimise the sensory impact of smoke taint in wine. Methods and Results: Different winemaking techniques were used to process smoke-affected grapes, i.e. cold maceration, the use of different yeast strains for primary fermentation and the use of oak and tannin additives. The extent of smoke taint in the resulting wines was determined by quantification of volatile phenols using GC-MS, followed by descriptive sensory analysis. Conclusions: Applied winemaking practices showed significant impacts on reducing the negative implications of smoke exposure on the chemical composition and sensory properties of wines. Winery processing methods that reduced skin contact time enhanced fruit character, produced wines with reduced 'smoke' aromas and flavours and less apparent taint. Selected yeast strains can be used as a tool for altering smoke-related aromas, flavours, colour and chemical composition of wines. The addition of oak chips and tannin enhanced the complexity of wines thereby reducing the perception of smoke-related attributes. Significance of the Study: These findings will enable winemakers to make more informed decisions when processing smoke-affected grapes, in order to minimise the severity of smoke taint perception in resulting wine.

Section: Oak Chips and Tannin Trialmentioning

confidence: 99%

The effect of winemaking techniques on the intensity of smoke taint in wine

Ristić

Osidacz

Pinchbeck

et al. 2011

112

“…The production of these substances varies with the combustion conditions such as moisture and oxygen availability, temperature and fuel composition (Maga 1988b, Hays et al 2002, Simon et al 2005. Fuel composition can also vary depending on the fuel type and source and it is generally comprised of lignin (18-35%), cellulose (40-45%) and hemicellulose (20-35%;Maga 1989). To date, there are no published reports on the effect of different fuels and fuel pyrolysis conditions on the development of smoke taint in wine.…”

Section: Introductionmentioning

confidence: 99%

Effect of smoke application to field-grown Merlot grapevines at key phenological growth stages on wine sensory and chemical properties

Kennison

Wilkinson

Pollnitz

et al. 2011

Background and Aims: Smoke exposure of grapevines and development of smoke taint in wine are issues of increasing incidence and severity. There is limited understanding of the effect of phenological stage at the time of smoke exposure on taint development. The aim of this study was to demonstrate the variation in smoke uptake and taint development between and within seasons. Methods and Results:Smoke was applied to field-grown Merlot grapevines at 12 stages of vine development over three growing seasons. Key periods of vine sensitivity to smoke taint in wine were (i) from shoots at 10 cm to full bloom (low levels of smoke taint); (ii) from berries at pea size to the onset of veraison (variable levels of smoke taint); and (iii) between 7 days post-veraison and harvest (high levels of smoke taint). Conclusions:The severity of taint in wine varied depending on the phenological timing of grapevine smoke exposure. Taint was elevated when exposure occurred between 7 days post-veraison and harvest. The carry-over of smoke constituents the following season was not detectable in wine but yields were reduced. Significance of the Study: This is the first study to demonstrate the timing of smoke exposure to critically affect wine chemical and sensory characters. These effects were consistent and reproducible over three seasons.

“…Guaiacol and 4-methylguaiacol are lignin degradation products (Maga 1984, Wittkowski et al 1992. These are commonly found in wines that have been aged in oak barrels (Towey andWaterhouse 1996, Pollnitz et al 2000).…”

Section: Introductionmentioning

confidence: 99%

Guaiacol and 4-methylguaiacol accumulate in wines made from smoke-affected fruit because of hydrolysis of their conjugates

Singh¹,

Chong

Pitt³

et al. 2011

Background and Aims: Taint in smoke-exposed grapes have been associated with elevated levels of guaiacol and 4-methylguaiacol. Previous research has reported guaiacol and 4-methylguaiacol in both fruits and wines. In some cases, these compounds were not detected, or were detected at low levels in the fruit while high levels were subsequently identified during or after winemaking. Later research indicated that this was due to the presence of glycosidic conjugates. Here we report a method for the routine analysis of guaiacol and 4-methylguaiacol released after acid hydrolysis of glycoside precursors. Methods and Results: Chardonnay, Merlot, Shiraz, Sangiovese and Cabernet Sauvignon fruits were collected following bushfire events in 2006-2007 in the King Valley wine region of NE Victoria, Australia. Gas chromatography-mass spectrometry (GC-MS) was used to detect free guaiacol and 4-methylguaiacol in both fruits and wines. Low levels of free and bound forms were present in fruit not exposed to smoke. Substantial levels of free guaiacol and 4-methylguaiacol were detected in the wines made from the smoke-affected fruits. These compounds increased during bottle storage. Acid hydrolysis of wines and berries resulted in a several-fold increase in free guaiacol and 4-methylguaiacol. Conclusions:The validated GC-MS method is suitable for monitoring free and glycosidically bound guaiacol and 4-methylguaiacol after acid hydrolysis in both fruits and wines. Acid hydrolysis of wines provided evidence that bound volatiles, most probably glycosidically, act as reserve for guaiacol and 4-methylguaiacol, which are released during ageing of wines. Significance of the Study: This is the first study published in a refereed journal to demonstrate that smoke taint-associated volatiles increase during ageing of wine and bound forms of guaiacol and 4-methylguaiacol represent an aroma reserve for smoke taint in ageing/bottled wines.