Sparkling Wine - Production

Production

The viticultural and winemaking practices of making sparkling wine have many similarities to the production of still wine with some noted divergence. At the vineyard, grapes are harvested early when there is still high acid levels. In areas like Australia, winemakers aim to harvest the grapes at 17 to 20° brix. Unlike still wine production, high sugar levels are not ideal and grapes destined for sparkling wine production may be harvested at higher yields. Care is taken to avoid tannins and other phenolic compounds with many premium producers still choosing to harvest by hand rather than risk mechanical harvesting which may split the berries and encourage maceration between the skins and juice. The press house is often close by the vineyard to where the grapes can be quickly pressed and separated from their skins. Red wine grapes like Pinot noir can be used in the production of white sparkling wines because their juice is initially clear and is only later tinted red through exposure to the color pigments in grape skins. While some skin exposure maybe desirable in the production of rosé sparklers and some blanc de noirs (white of blacks), most sparkling wine producers take extended precautions to limit the amount of skin contact.

The primary fermentation of sparkling wine begins like most other wines, though winemakers may choose to use specially cultivated sparkling wine yeasts. The wines may go through malolactic fermentation, though producers wishing to make fruitier, simpler wines will usually forgo this step. After fermentation the base wines are then blended to form a cuvee. While there are examples of varietal sparklers, such as blanc de blancs (white of whites) made from 100% Chardonnay, most sparkling wines are blends of several grape varieties, vineyards and vintages. Producers with wide access to grapes will use wines from several hundred base wines to create a blend that reflect the "house style" of their non-vintage wine. It is through the initiation of a secondary fermentation that distinguishes sparkling wine production and gives the wine its characteristic "bubbles". One of the by products of fermentation is the creation of carbon dioxide gas. While this gas is able to be released during the first fermentation, efforts are taken during the second fermentation to retain the gas and have it dissolve into the wine. This creates a high pressure within the wine bottle (on average around 5 atmospheres) and wine producers take care to package the wine in strong glass bottles. When the wine is open and poured into a glass, the gas is released and the wine becomes sparkling.