As is the case with all wines, the quality of fruit is critical in determining the ultimate quality of the wine. For premium sparkling such as Champagne in France, the varieties used are Chardonnay, Pinot Noir and Pinot Meunier. However, other internationally recognized sparkling regions may use other varieties eg. Asti Spumante uses Muscat Blanco.
At the very commercial, high volume end of sparkling wine production, the varieties used becomes more diverse with varieties such as Colombard, Shiraz, Sultana and Chenin Blanc.
Cooler climates bring out the best features of Chardonnay, Pinot Noir and Pinot Meunier for the making of premium quality sparkling wines.
Cool climates are considered ideal for sparkling wine production due to the fact that higher natural acidity is retained and a higher intensity of varietal characters is developed at lower sugar levels. The structure of the resultant wine is more suitable for fine, elegant sparkling wines with a propensity for longer maturation.
Generally, it is agreed that grapes for sparkling wine will be picked earlier than those
destined for table wines. This is done:
The Primary Fermentation
In the first instance, a base wine is produced the same way as a still white wine. However, the differences are generally that the grapes for premium sparkling wines are hand picked, whole bunch pressed with no skin contact and all pressing factions kept separate. The base wines for a sparkling are generally high in acid and delicate in flavour. The ultimate base wine (Cuvee) is generally a blend of many different components in order to achieve the right balance and desirable "house" style.
The Secondary Fermentation
The overall equation for fermentation is:
C6H6O6 Þ 2C2H5OH + 2CO2
Sugar (Glucose) + Yeast Alcohol (ethanol) + Carbon Dioxide
When making the base wine, the carbon dioxide produced in the fermentation process is not required and therefore released into the atmosphere. When producing a sparkling wine, the carbon dioxide is the prime reason for the fermentation. The amount of sugar required to create the desired amount of carbon dioxide is calculated by using the above equation. This, together with yeast specifically selected and propagated to ferment under the harsh conditions of pressure fermentation, is mixed with the Cuvee.
Méthode Champenoise, or Traditional Method, is a method developed in the Champagne region of France, where the 'sparkle' is created in the same bottle in which the wine is sold.
Traditionally about 24 grams/litre of sugar is added which will ferment to approximately 1.3% vol/alc and give sufficient carbon dioxide to create five to six atmospheres of pressure. The yeast used has been selected due to the fact that it is particularly good at flocculation and also easy to shake (riddle) to the neck of the bottle for extraction.
This mixture, together with possibly an additive to assist the remuage process, is bottled and sealed with a crown. This is called the "tirage" process, and the bottles are stacked on their sides in cool, dark cellars.
Secondary Fermentation
Secondary fermentation takes place within the bottle, leaving sediment, which is
subsequently removed.
The bottles are normally stored horizontally at about 12ºC and the secondary fermentation takes around four to eight weeks.
Ageing
When secondary fermentation is complete, the wines are left to mature, resulting in the wine gaining aroma and flavour. The ageing on lees is a major contribution to the style of the wine. The longer the time, the more chance of picking up characters released from the decaying yeast cells in the process known as yeast autolysis.
Remuage
Remuage, or riddling, is the method used to move sediment toward the necks of the bottle, prior to its removal. Historically, this is done by hand using A-shaped wooden frames specially designed to allow the bottles to gradually be turned and brought from the horizontal to the vertical position. As this occurs, the sediment is moved from the side of the bottle to the neck. This very labour intensive system takes around 20-30 days to complete. Today, many companies have moved to mechanical processes using gyropallets. Large crates are electronically rotated and shaken from the horizontal to the vertical in a few days using this process.
Dégorgement and Bottling
Once the bottle has been inverted, the next process is called dégorgement (or
disgorgement), the removal of lees now collected in the neck of the bottle. The neck
containing the sediment is snap frozen by immersing it in a solution of around -30ºC. Once this has occurred, the bottle is up-ended, opened and the ice plug (containing the deposit) is ejected by the gas pressure. As the wine is cold, there is minimum gas lost from solution during this process. The bottle is then topped up with the same wine and normally sweetened with liqueur d'expédition to give it the desired balance. Even wines designated as "brut" are sweetened and contain 5-12 grams/litre of residual sugar. The bottle then has the cork inserted and the wire (muselet) is applied. The bottle is then dressed for the market.
This process differs from the Méthode Champenoise in that the remuage and dégorgement processes are dispensed with. Once the wines have been given the desired time on lees, the contents of the bottle are removed under counter pressure into a pressurised tank. The wine is then filtered to remove the deposit formed during the secondary fermentation. The liqueur is added and then, once again under counted pressure, the sparkling wine is bottled.
This process allows for more uniformity in the finished product and can allow for the
blending of different batches and vintages after the secondary fermentation and lees ageing process. As the bottle is not submitted to the rigours of the complete
Méthode Champenoise, the bottle used in the final bottling is often a lighter weight than those used in the traditional process.
Wines made from the transfer process may be labelled as "Bottle Fermented".
Wines made under this process tend to be commercial sparkling wines and not produced from premium varieties. As the wine has not spent the same amount of time in contact with the carbon dioxide, the bubbles tend to be large and dissipate at a faster rate.
The base wine is blended, sweetened and chilled. Carbon dioxide is infused into the
pressure tank until the required amount of pressure is achieved. The wine is then bottled under counter pressure. Once again, the bubbles are larger and diffuse more readily. These wines must be labelled as "carbonated".
Cellaring
It should be noted that all sparkling wines are ready to consume on release. Some bottle age after disgorgement may add some extra characters to a sparkling wine, however, generally speaking most should be consumed within 2 years of packaging.
Bottle Sizes
| Size | 750ml Equivalent |
| Magnum | 2 |
| Jeroboam | 4 |
| Rehoboam | 6 |
| Methuselah | 8 |
| Salmanazar | 12 |
| Balthazar | 16 |
| Nebuchadnezar | 20 |
