Vineyard & Winery Management

September/October 2012

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WINERY SOIL & CELLAR Fermentation oving away from using stock stainless steel tanks, both commercial and artisan wine- makers are able to customize and elaborate their fermen- tation plans and create diversity and distinction through the use of an array of fermentors. Some are choosing to embrace ancient mate- rials, and in some cases, are repur- posing them for use in modern winemaking facilities. Wood fermentation vessels are experiencing a renaissance in mod- ern winemaking. Although it is impossible to sterilize wood, and difficult to sanitize it, the benefits of using wood fermentation vessels are outweighing these challenges for many winemakers. Barrels have often been used for white-wine fermentation, especially for oak- influenced wines such as chardon- nay, to achieve more integration and complexity earlier in the life of the wine. However, they have recently SHORT COURSE Stainless steel tanks are now joined in the cellar by wood, con- crete and clay fermentors. Today's technology is applied to ancient materials, giving wine- makers more control over fermen- tations. Vintners choose the types and shapes of their fermentors based on the style of wines to be pro- duced. Amphorae vessels are popular with non-interventionist winemakers. WWW.VWM-ONLINE.COM REMI COHEN Innovation Wood, concrete and clay vessels are back, with modern twists become more popular for red-wine fermentations. Barrels have the advantage of serving as a fermentor for small vineyard lots, either small blocks or a section of a block that may have different attributes than the rest of the block. In barrel fermentation, cooling only occurs through passive heat radiation to the walls of the barrel. Therefore, it's more difficult to con- trol temperatures with barrel fer- mentations; they may heat up more than desired and dissipate acetate esters more readily than in a cooler fermentation. In certain aromatic whites, this can be problematic but the problem can be solved by keep- ing the barrel in a cool room for a slow white-wine fermentation. Alternatively, barrel fermenta- tions of red wines may not gener- ate enough heat for extraction and lead to a gentler extraction, which could be favorable; heaters or warm- er rooms can help maintain hotter fermentation temperatures. It is important to note, as fermentor size increases, the heat generation rate during fermentation increases more rapidly than the dissipation rate, and the maximum must temperature increases accordingly. Advantages of barrel fermenta- tion include earlier tannin polym- erization and earlier integration of oak tannins, making for improved concentration of tannins and a smoother tannin mouthfeel. The characters imparted to wine from oak are different if the oak is pres- ent during the fermentation than if the wine is added to the oak post- fermentation, because yeast can metabolize or transform certain Remi Cohen is a vineyard and winery con- sultant based in Napa Valley whose primary areas of expertise include viticulture, sus- tainable vineyard management, winemak- ing, grower and winery relations, and stra- tegic business development. She writes a wine industry blog, which can be found at blog.vinestowine.com. characters present in the oak. Furan aldehydes, for example, are reduced to furfuryl alcohols and yeast also metabolize vanillin, resulting in less vanilla aroma in an oak-fermented wine compared to an oak-aged wine. The impact of oak decreases dramatically each year of its use, so a barrel being used for a third or fourth fermentation may serve as a small vessel for fermentation with lees contact and oxygen ingress, but with minimal oak flavor impact. INCREASED COSTS Barrel fermentation comes with increased costs of managing and monitoring many small, individual fermentations. Additionally, there may be costs associated with removing and replacing barrel heads. A winery will have to remove and replace barrel heads if it chooses to ferment with the barrel upright, using punchdowns for extraction. Fermentation in puncheons delivers early oak integration without over- whelming wines with oak character. SEPT - OCT 2012 VINEYARD & WINERY MANAGEMENT 33

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