Wine In Wood And Wood In Wine: Latest developments in oak alternatives

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WINE IN WOOD AND WOOD IN WINE
Latest developments in oak alternatives
by Charl Theron
Oak alternatives have been used in the wine industry for many years, one of the reasons being price when compared with traditional oak barrels. This motivation obviously inspires innovative thoughts and actions to adapt existing oak alternatives or develop new ones.
As with oak barrels there are no standard directions for the use of oak alternatives, considering that circumstances and wine styles differ. However, certain basic guidelines apply:

European oak compared to American oak results in more ellagic tannins, but fewer methyl octalactones in the treated wine.
Increased toasting of American oak causes a marked increase in vanillin until a peak in concentration, whereafter it decreases drastically; European oak on the other hand usually has a more constant vanillin quality as a result of milder toasting.
The toasting and source of the oak impact on the formation of the volatile phenols in the oak. The formation of smoky or spicy flavours is more intense, for example, with toasted American oak.
Experiments have been conducted in which wine was respectively fermented without oak, fermented and left on oak chips for four weeks and fermented without oak, then left in contact with oak chips for four weeks. In general this confirmed that fermentation in contact with oak promotes better integration of wood flavours and polyphenols. The dimensions of the oak alternatives compared to oak barrels obviously benefit the reaction. The simultaneous presence of lactic acid bacteria and oak also improves the release of oak related flavourants. In the case of cultivars such as Sauvignon blanc and Riesling the oxidation influence of the oak products may cause a reduction in the pronounced cultivar character. In the case of oak contact during red wine fermentation this may result in the earlier stabilisation of the red colour.
The type of oak alternative will also impact on the wine that is being treated. Untoasted oak, for example, is considered to promote the expression of fruit in the wine, because it contains more ellagic tannins, but fewer oak flavours than toasted oak. Due to the greater sensitivity of the ellagic tannins to oxidation, the flavour compounds in the wine are protected against oxidation. Oak with a high ellagic tannin content is preferred for Botrytis wines, as it reduces the risk of enzymatic oxidation.
Untoasted oak is sometimes used to remove undesirable sulphur compounds such as hydrogen sulphide and mercaptans, although favourable sulphur compounds associated with certain cultivar wines may also be removed. The use of untoasted oak is also risky as it may result in undesirable characteristics in the treated wines such as bitterness, lignin character, green character and mould character. The shape and dimensions of oak alternatives also play a vital role. Small oak particles are preferable early in the vinification process, being easy to use and obviously offering greater contact surface. Staves on the other hand will impart a slower, less intense oak character, but more complexity.
The selection of a particular oak alternative is also determined by the oak strategy of the winemaker. Different products will be used depending on whether the purpose of the addition is increased flavour, colour stability or greater complexity. The latter could be obtained for example by using a combination of American and French oak, since the characteristics of these two woods differ considerably. The character of white wines necessitates lower dosages of the products and the addition of American oak chips or powder after maturation may enhance the fruity character of certain cultivars. The use of oak alternatives in unfined red wines will improve the integration of grape tannins and oak and lower dosages are recommended for a longer contact period (Penn, 2008).
There are different physical types of oak alternatives, some of which are already established on the market, but new products are still being developed. Oak powder is very fine and gets blown in all directions, which favours the choice of staves placed in tanks and barrels. Although oak alternatives may impart oak character to wines more quickly, the same preparation of the oak than with barrels is required. Natural open air leeching and the toasting process of the oak are vitally important. Toasting of the alternatives over an open fire, for example, imparts a toasting character which approximates toasted barrels more than when using convection heating in ovens. Winemakers who previously used barrels exclusively may consider a gradual switch to oak alternatives by blending wines that were matured in barrels with wine that has been treated with oak alternatives (Dolan, 2008).
More information about oak alternatives may be obtained from the following websites:
www.innerstave.com
www.stavin.com
www.oaksolutionsgroup.com
www.nadalie-usa.com
www.tonnelerieradoux.com
www.bouchardcooperages.com
www.worldcooperage.com
www.cantoncooperage.com
References
Penn, C. 2008. Pascal Chattonet: Achieving great wine with oak alternatives. Australian & New Zealand Wine Industry Journal 23(5): 47 - 49.
Dolan, T.C. 2008. Update on Barrel Alternatives. Trends Accelerated by Rising Cost of Oak Barrels. Vineyard & Winery Management, July/August 2008: 62 - 67.
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