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Tuesday, December 7, 2010

Viniviticulture in the Medoc and Graves

Grape growing and winemaking in Bordeaux is classical in the sense that most of the core viniviticultural processess predominant in the world today can trace their roots back to Bordeaux.  On the left bank vines are planted at high densities to induce stress and are trained low to take advantage of heat reflected from the gravelly terrain.  The better chateaus have a higher percentage of old vines and implement rigorous replanting regimes in order to optimize vineyard potential.  Yields are closely managed through actions such as pruning and green harvesting.  For the most part, grapes are machine harvested with hand-harvesting reserved for the finest wines.

Once in the winery, grapes are subjected to scrutiny at a sorting table where unsatisfactory fruit and unwanted objects are removed.  Both black and white grapes are crushed to break the skins and stems are removed from the white grapes; black grapes may or may not be de-stemmed.  White grapes are pressed to remove the skins and are then shunted to the fermentation tanks for the initiation of that process.  Black grapes are allowed to macerate for between 15 and 21 days -- including fermentation and post-fermentation -- in order to extract tannins, color, and flavors from the skins.  White wines will ferment for 12 - 15 days between 10 degrees and 20 degrees Celsius while red wines ferment between 8 and 10 days at 28 to 30 degrees Celsius.  Fermentation is carried out in temperature-controlled, stainless-steel tanks or epoxy-lined concrete vats. The choice of yeast to ignite the fermentation process is the winemaker's decision but many winemakers opt for cultured yeasts in order to reduce uncertainty.  During and after fermentation the must is kept in contact with the skins through a pumping-over process (Punching down of the cap is also utilized but pumping-over is more prevalent.).

Post the red-wine fermentation process, the free-run juice is bled-off into storage vats while the remaining engorged skins are pressed to extract the remaining juice.  This pressed juice is stored separately from the free-run juice.  Red wines undergo malolactic fermentation wherein the hard malic acid is converted into softer lactic acid.  This process is optional for white wines which may, instead, go directly from fermentation to racking.  Both red and white wines are racked to vats or oak barrels for cellar ageing.  Sulfur is added at this time to stabilize the wine and combat oxidation.  The oak barrels are 225 liter in volume and can range from neutral to 100% new oak.  The best wines will be placed in 100% new oak barrels and will be resident therein for 24 months.

In many cases, plots and varietals have been vinified and stored separately and blending these separate wines into the final product prior to bottling is one of the critical tasks of the winemaking team.  Based on the results to date, it is a task that they are especially well-equipped to handle.

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