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A Technical Guide for Wine Producers
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RECENT ARTICLES | WYNBOER HOME
Wine In Wood And Wood In Wine
Specific Barrels for Specific Cultivars
Charl Theron, extraordinary lecturer in Oenology, Tim Rypstra, professor in Wood Science and Jan Swart, director: Wood and Fibre Institute.
Together with the grapes that are being used, the wood that is selected for vinification or maturation plays the most important role in the flavour and taste characteristics of wine. In addition to the unique and expressive compounds that may be extracted from the wood, the interaction between the grape compounds, fermentation compounds and the oxygen uptake during maturation or micro-oxygenation result in specific flavour and taste characteristics. These characteristics might possibly be increased or decreased by using specific barrels for specific cultivar wines.
The toast flavours of Chardonnay, the spiciness of Zinfandel and the cedar or tobacco character of Cabernet Sauvignon are largely derived from the wooden barrels in which the wines are vinified or matured. Barrels consequently account for an integral part of the mystique and romance of wine.
The cooperage industry has been applying new technologies and chemical analyses to address specific wine requirements in conjunction with coopering tradition. Cooperages agree on the importance of the oak species being used, the necessity to age the wood for at least 18 to 24 months and the grain of the wood, but the toasting practices of individual cooperages could ensure a bigger variation of barrels.
Various important compounds occur in wood. Cis G-Octalactone is the dominant flavour compound of untreated wood and smells like coconut. Vanillin is responsible for the vanilla character that derives from the wood and eugenol has a clove-like flavour. Ellagic tannins are the tannins that occur naturally in wood. The above-mentioned flavour compounds, apart from tannins, are concentrated during the natural ageing of wood before construction of the barrels. During the toasting process of the barrel the quality thereof is practically doubled. The ellagic tannins are reduced by the wood ageing process, however, and so too by increased toasting of the wood.
The toasting management of individual cooperages with regard to toasting method, toasting temperature and degree of toasting may impart an individuality to barrels that has the biggest influence on wine style and quality. Which means that the purchase of barrels should no longer be determined by tradition and romance, but rather by their suitability for a specific cultivar or even vineyard.
As a result, different cooperages recently began to focus their research on more specific application of barrels.
World Cooperage developed a system known as "Barrel Profiling" to monitor the different flavour and tannin levels during toasting. The toasting process is applied by means of a computer network which manages the humidity of the wooden staves, air flow, time and toasting temperature. Cellars are therefore able to indicate their cultivar and desired wine style, whereafter the cooperage supplies barrels with different profiles to the cellar for the necessary experimentation and possible adjustments to the toasting process before a final barrel order is placed. By so doing barrel differences may be limited to a minimum.
Radoux has also experimented with cultivar specific barrels for white wines by using chemical analyses combined with sensorial evaluation. Their research confirmed the importance of wood grain. Wood with a finer grain results in more flavour and less tannin in wines and wood extraction by the wine also takes place more slowly. The opposite is true for wood with an increasingly coarse grain. Furthermore they focussed on the toasting process by dividing it into three phases. Firstly a pre-toasting process, when water and heat are used to render the wood supple. This is followed by a slow toasting process at a constant temperature. The final process, known as "bousinage", is applied by placing a lid over the barrel so as to concentrate the toasting process. This last phase has the biggest influence on the flavour profile imparted to wine by barrels. By using different grain and toasting combinations, Radoux offers winemakers 800 different choices.
Nadalie is more secretive regarding their research, although they do offer barrels that impart a fruity or spicy character to the wine.
The Oak Tradition Cooperage experimented with white wine barrels made from acacia (Robinia pseudoacacia) in order to accentuate the floral character of white wines. This apparently imparts a predominant honey character to the wine.
The representative of Francois Frères and Taransaud is nevertheless sceptical about this approach, since it may be interpreted as a marketing gimmick. This view is shared by StaVin, a California-based supplier of alternative wood products.
Reference:
Cutler, L. 2006. Can Varietal-Specific Barrels Make a Difference? Wine Business Monthly May 2006: 20 - 23.
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