Sparkling Wines – Ways and Styles
This edition of Carl’s Corner was inspired by McPherson Cellars Sparkling Wine currently available and often enjoyed at the Texas Wine Collective tasting room. Sparkling wines are very popular in the wine world today, including Texas. Making sparkling wines can be technically challenging and time-consuming, but for those who enjoy the final product, it certainly seems worthwhile. There are actually a number of methods used to produce sparkling wines, and this post will explore five (5) primary methods, each providing a level of carbonation and a particular style of wine.
The traditional method, called Methode Champenoise in France, is the most technically challenging, time consuming, and costly. In this method, the transformation of a still wine to a sparkling wine occurs inside the bottle. Grapes are picked, typically a bit less ripe to provide higher natural acidity, and made into a dry, still wine. Often different batches of still wines, or cuvées, are blended together to create a stylistically consistent base wine. A carefully measured amount of sugar (or grape concentrate) and yeast are then added to the base wine (called tirage), and this is bottled with crown caps. The secondary fermentation takes place in the sealed bottle producing a bit more alcohol and carbon dioxide (the bubbles). The yeast eventually dies, but can be left to interact with the bubbly wine to enhance flavor during aging.
The time-honored process of gently turning the bottles and tilting them until they are upside down is called riddling, and moves the yeast sediment to rest on the cap in the neck of the bottle. Eventually the winemaker will disgorge the wine, removing the sediment by freezing the liquid at the cap, thus capturing sediment in an ice plug. The crown cap is removed and the ice plug pops out of the bottle. The amount of wine removed during disgorgement is then replaced with a dosage of wine, often sweetened with sugar, to generate the final wine which is then finished with cork, capsule, safety wire, and label. This process will produce about 75-95 psi pressure that the thick sparkling wine bottle is designed to hold. This traditional method involves a lot of steps and a lot of work, but is used to produce many of the top-tier sparkling wines.
A different tank or Charmat method generates pressure in a tank rather than in individual bottles. In this case, a carefully measured amount of sugar (or grape concentrate) and yeast are added to the base wine (tirage), in a pressure-holding tank. As the second fermentation occurs in this tank, yeast sediment falls to the bottom. Eventually the dosage is added and the final wine is filtered from the tank and bottled, usually with little or no aging. These Charmat sparkling wines often have a fresher character with a bit less carbon dioxide pressure, in the 30-60 psi range. This process is more affordable than the traditional method, but is still used to produce much higher quality sparkling wine - such as the delicious McPherson Cellars Sparkling Wine that uses Chenin Blanc grapes from Texas High Plains vineyards.
An option to eliminate the need for riddling and disgorgement is called the transfer method, or transversage. Like the traditional method, sparkling wine is made in bottles which are then opened and emptied into a pressurized tank. The yeast sediment settles and the wine is filtered under pressure into a pressurized bottling system. This method is most often used for non-standard sized bottles, like splits and larger magnum or jeroboam bottlings. The pressure in bottle is still typically in the 65-95 psi range.
The Methode Ancestral or Ancestral Method has been used for hundreds of years to produce sparkling wines around the world. There seem to be two key variations for this method. In some cases, cold temperature and/or filtration are used to pause the fermentation process before all the sugar is converted to alcohol. Later, the wines in bottle are allowed to warm, thus restarting fermentation that will consume all remaining sugar, raising the alcohol level and capturing carbon dioxide. The wines can be further chilled, riddled, and disgorged like the traditional method, or emptied into a pressurized tank and filtered before finishing, like the transfer method. However, purists typically do not add any sweetened dosage before finishing with cork, capsule, safety wire, and label.
Another variation on the Ancestral Method is used to produce many of the Petillant Naturel (Pet-Nat) wines that have become very popular here in the Lone Star State. In this case, a still wine fermentation is allowed to almost reach the finishing point, leaving just the right amount of sugar and some residual yeast in the wine. This is then bottled, and usually sealed with crown caps, wherein the final bit of fermentation takes place in the bottle. This will produce carbon dioxide pressure, but will leave a bit of yeast sediment to be dealt with when the botte is finally opened for consumption. All variations of the Ancestral Method tend to produce wines with 30-60 psi carbon dioxide pressure.
The final method mentioned in this post is direct carbonation. In this case, still wine is contained in a pressurized tank and carbon dioxide gas is injected until an appropriate level of pressure, typically 45 psi, is reached. This lower-cost method is most often used for lower quality, bulk-distribution sparkling wines, but there is no reason why a higher quality base wine could not be used to produce a better final product.
The information in this post is based on the author’s personal experience in producing sparkling wines and the following excellent reference article by Madeline Puckette. https://winefolly.com/deep-dive/how-sparkling-wine-is-made/, 6-Jun-2016, updated 10-Sep-2019.