Creating A Smoky Aroma In Wine: The Secret Techniques

Wine is a complex beverage with a multitude of aromas and flavours that can be attributed to various factors such as grape variety, terroir, vinification, and ageing. One intriguing aspect of wine appreciation is the presence of smoky aromas, which can elevate a wine's complexity and intrigue. While some may find the idea of smoky wine unusual, it is a sought-after quality in certain wines, adding savoury characters and intriguing secondary and tertiary notes. In this article, we will delve into the world of smoky wines, exploring how they attain this unique characteristic and where to find them.

Toasting oak barrels

Toasting an oak barrel involves exposing the inside of the barrel to varying degrees of heat over a specific amount of time. This process can be done using different methods such as fire, infrared waves, or convection, with fire being the traditional method. The amount of heat and time of exposure are the two key factors that determine the flavour profile of the barrel.

The toasting process causes chemical changes in the wood, creating or destroying flavours. A skilled cooper can manipulate these flavours by controlling the heat and time, similar to how a chef adds spices to a dish. The type of oak used also plays a crucial role in the toasting process, as different species of oak have distinct flavour characteristics. For example, Allier forest oak is known for its delicate and refined aromas, while Troncais or Limousin forest oaks have more robust flavours.

There are generally three levels of toasting: light, medium, and heavy. Light toasting, with temperatures ranging from 120-180 °C (248-356 °F), gives the barrel a spongy appearance and imparts flavours like vanilla, coconut, and cinnamon. Medium toasting, at temperatures of approximately 200 °C (392 °F), results in a warmer, sweeter character with strong vanilla overtones. Heavy toasting, exceeding 15 minutes of exposure and temperatures of 230 °C (446 °F), produces a blistered and cracked surface on the barrel and contributes flavours such as vanilla, espresso, smoke, and crème brûlée.

The choice of toasting level depends on the style of wine being produced. For instance, medium plus toasting, which falls between medium and heavy toasting, is considered ideal for red wines as it offers aromas of honey, roasted nuts, and a hint of coffee and spices. On the other hand, light toasting is often used for white wines, as it imparts more aroma than flavour, with notes of French oak, coconut, and fruit.

Terroir

The concept of terroir was developed by French winemakers over centuries, through observing the differences in wines from different regions, vineyards, or even different sections of the same vineyard. Winemakers in ancient times also recognised that different regions could produce very different and distinct wines, even from the same grapes.

The components of terroir often described include:

• The interaction of climate and terroir, which can be broken down from the macroclimate of a larger area to the mesoclimate of a smaller subsection, and even to the microclimate of a particular vineyard or row of grapevines.
• The element of soil, including its composition and intrinsic nature, such as fertility, drainage, and ability to retain heat.
• Geomorphology, or the natural landscape features like mountains, valleys, and bodies of water, which affect how the climate interacts with the region, including the aspects of aspect and elevation.
• Other organisms, flora, and microflora growing in, on, and around the vine plots, which can include region-specific fauna and microbial populations.

While the term 'terroir' originally referred to earthy notes in many Old World wines, today it is used more broadly to describe practically every wine region. The traditional notion of terroir is also challenged by modern winemaking techniques, such as oak influences, over-ripened fruit, cultured yeast, micro-oxygenation, and colour pigment additives, which can obscure or eliminate the influence of terroir in making wines from different regions unique.

When it comes to giving wine a smoky aroma or flavour, this can be achieved through various means, including the amount of toasting an oak barrel receives before ageing the wine. A medium or heavier toasted barrel can impart smoky aromas or flavours that are particularly noticeable in the bouquet. Smoky flavours can also be added through cheaper alternatives, such as oak substitutes or smoke-flavoured liquid additives. However, these substitutes may result in unbalanced flavours, whereas flavours derived from oak are typically more integrated and balanced.

Smoke taint is another factor that can contribute to smoky flavours in wine. Vineyards and grapes exposed to smoke, such as those affected by bushfires, can result in wines with smoky, burnt, ashy, or medicinal notes. While smoke taint can add character to the wine in small doses, it can become a fault if it dominates the other flavour profiles.

Smoke taint

Several factors influence the level of smoke impact on grapes, including the stage of berry development, grape variety, smoke type and concentration, and duration of exposure. Wildfires in forested areas release volatile phenols into the atmosphere, which can then be absorbed by developing grapes in nearby vineyards. These bound phenols, or glycosides, typically have no taste or smell until the bond with the sugar is broken during winemaking processes or ageing. When the volatile phenols are released, the characteristic "smoky" flavour becomes detectable. This bond can also be broken upon tasting when the affected wine comes into contact with enzymes in saliva.

The primary volatile compounds responsible for smoke taint include guaiacol and methylguaiacol, with others such as ortho-, meta-, and para-cresol, as well as syringol and methylsyringol. There are enological laboratories that can analyse the presence of these compounds and help wineries interpret the results.

If grapes have tested positive for smoke effects, there are measures that can be taken to minimise, remove, or counterbalance the impact of smoke taint at various stages of the winemaking process. Common treatments include minimising skin contact and maceration, adding oenological tannins and/or oak chips to contribute structure and counterbalance the smoke taint, and using fining and/or filtration techniques to remove or reduce smoke compounds.

Barrel alternatives

The use of oak barrels to age wine and impart a smoky aroma is a time-honoured tradition. However, there are several alternatives to oak barrels that can be used to achieve similar results. These alternatives offer winemakers new opportunities, mimicking the best aspects of oak casks while giving customers the desired oak-influenced flavour profile. Here are some of the most common barrel alternatives:

Oak Staves

Oak staves are oak planks that are bolted into stainless steel tanks. They add wood character to the wine without allowing oxygen in. To compensate for the lack of oxygen, winemakers use micro-oxygenation, a simple process where a pump dribbles oxygen into the wine. This step may require extra work but saves space and money compared to using barrels.

Oak Chips

Oak chips are small chunks of oak that would look at home in a backyard smoker. They have a high surface-to-volume ratio, infusing wine with flavour more quickly than a long, thick stave. Oak chips are often added to the grape must during fermentation. The molecules in the wood interact with the juice to stabilise colour and tame vegetal aromas, such as bell pepper.

Oak Dust/Powder

Oak dust or powder is made from oak shavings, similar to those created by a pencil sharpener. These fine flecks are mixed with grape juice during fermentation. While they do not impart a strong oak character, the molecules in the wood interact with the juice to stabilise colour and tone down vegetal aromas.

Oak Bottles

There is even a product called the Oak Bottle, which is a 750 ml oak wine bottle that sells for $80. It is marketed as being able to make a $3 bottle of wine taste like a $20 bottle of wine.

Other Alternatives

Other alternatives to traditional oak barrels include oak pieces in various shapes and sizes, such as oak cubes and oak fans. These alternatives offer a faster way to impart oak flavours to wine due to their increased surface area in contact with the liquid. They are also more cost-effective, as more of the oak tree can be used, and there is no need for a skilled cooper to craft a barrel.

While some may view the use of barrel alternatives as a shortcut or stigma, they offer several benefits to winemakers, including cost savings, consistency in flavour, and environmental sustainability.

Aging

During the aging process, the wine extracts volatile compounds from the oak, which contribute to its sensory characteristics. The most prominent of these compounds are lactones, particularly cis- and trans-methyl-octalactones, which are known for their oak and coconut aromas. Additionally, vanillin and its derivatives lend a vanilla flavour, while small phenolic compounds like eugenol and guaiacol contribute spicy, clove, and smoky notes. Furfural and 5-methylfurfural, derived from oak, impart almond and toasted almond aromas.

The amount of time wine spends aging in oak barrels also affects its flavour and aroma profile. Prolonged exposure to oak can result in unbalanced flavour profiles with strong oak aromas. On the other hand, shorter aging periods may not allow enough time for the desired compounds to be extracted from the wood. Therefore, finding the right balance is crucial.

Another factor to consider is the level of toasting applied to the oak barrels. A medium or heavier toast can add smoky aromas to the wine, while a lighter toast may result in less pronounced smoky notes.

Furthermore, the species of oak used for aging can also make a difference. American white oak (Quercus alba) and two European oaks, sessile oak (Quercus petraea) and pedunculate oak (Quercus robur), are commonly used for wine aging. Each type of oak has a unique chemical composition that will impart distinct flavours and aromas to the wine.

In conclusion, aging wine in oak barrels is a complex process that requires careful consideration of various factors. By manipulating the type of oak, level of toasting, and aging duration, winemakers can create wines with desired sensory characteristics, including smoky aromas.

Frequently asked questions