Learn About White Wine Production: Part II

Date January 17, 2009

Let’s continue to learn about white wine production, shall we?

If you missed the first part of this series you can find it here:
Learn About White Wine Production: Part I

On to Primary Fermentation.

Once the wine must is prepped, settled, acidified and/or chaptalized, it is ready for fermentation.

It is typical today for winemakers to use large fermentation tanks for the primary (or alcoholic) fermentation of white wine. Smaller winemakers use wine making kits and ferment their wines in eight gallon buckets cooled in keg coolers or something similar. The larger steel tanks are artificially cooled between 50-60° F in order to preserve the natural aromatics of the white wine grape. It’s an extensive process and usually takes two to six weeks, however, in extreme instances it can go on for much longer.

Old school winemakers continue to use wine casks to ferment their white wines in cool storage areas not unlike the fabled Area 51 in Nevada. Just kidding. The insulating properties of wood casks enable fermentations to successfully progress in barrels because the heat that is generated by the yeasts is trapped and keeps the temperature warm enough for the process to continue, even in cool climates. Likewise, in warm climates barrel fermentation temperatures can be maintained by placing casks in cool basement wine cellar, a cave, or an air-conditioned winery.

Secondary Fermentation, Racking, Sur Lie Aging, Bâttonage, and Sulfur Adjustment

Secondary fermentation, also known as malolactic fermentation is an optional step that winemakers can opt to take place along with alcoholic fermentation or after primary fermentation is complete. In this stage of fermentation, lactic bacteria is added to soften the harsh malic acid astringency by converting the green apple flavors of malic acid to the butter, butterscotch, toffee and caramel flavors of lactic acid.

When the fermentation stage reaches its end, carbon dioxide production halts. As the gas dissipates, yeast cells die and settle to the bottom of the tank or barrel as sediment (better known as lees). From there the wine goes through racking (removal of the lees) or it can be left on top of the dead yeast cells for further aging. This is known as sur lie aging. Sur lie aging imparts rich toasty and nutty characteristics to a finished wine. Bâttonage is the process of lees stirring. This intensifies the toasty, nutty flavors while adding a “creamy mouthfeel” to the wine.

Sometimes a wine goes through several rackings after fermentation or sur lie aging to let the wine “fall bright” or become clear, meaning simply that all the sediment is removed. Sulfur levels are adjusted at this point. While wine naturally produces sulfites during fermentation, most winemakers add extra sulfur to prevent microbial spoilage, browning of the wine and oxidation.

The final part of the series, Learn About White Wine Production: Part III, will talk about clarification of the wine, stabilization, bottle aging, blending and bottling. Learn about wine and what this is, next.

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Related posts:

  1. Learn About White Wine Production
  2. Learn About Wine Fermentation
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