When one see this magical elixir bubbling away with almost no color or at most, a very light straw color, few would suspect that up to 60% or more of the grapes used to produce it are red wine grapes. The red wine grapes used are Pinot Noir and are treated as a white wine grape with no skin exposure. In addition the fruit is very gently pressed removing only a portion of the juice. This gentle press is sometimes called a basket press. A ton of wine grapes may produce 160 gallons or more, yet the sparkling wine producer may extract only the first 100 to 110 gallons, thus preventing the leaching of color from the skins.
Brix is a term which refers to a measurement made of the refractive index of the total dissolved solids found in the juice, or must, most of which are sugars. An instrument called a refractometer or hydrometer is used to do this measurement. Most wine grapes used in the production of sparkling wines are picked when the brix in the juice reaches around 19 brix. This compares to most other wine grapes being harvested at 22 &Mac185; brix to as high as 30 brix in some cases.
A cool fermentation is achieved in tanks equipped with cooling jackets. Malolactic fermentation often follows.
Prior to bottle fermentation (methode champenoise,) the cuvee is blended. The blend is created based on tasting and may include wines from various years and growths. Following blending, the wine is clarified by fining and filtering. The addition of the tirage syrup is made. The tirage syrup consists of 24 to 26 grams of sugar per liter, yeasts, and nutritive additives to help fermentation. Bentonite, a type of clay is added to aid the clarification and settling of the solids still present in the wine. The secondary fermentation takes place in the same bottle from which the sparkling wine is eventually consumed. This secondary fermentation is slow and takes place at about 55 degrees Fahrenheit.
The bottles are then capped with special caps which have a small container which fits into the neck of the bottle. The secondary fermentation takes several months and then the wine ages several years on the yeast sediment. Riddling on racks, or remuage, is a process destined to get the sediment to sink into the cap in the neck of the bottle. Riddling involves the slow rotation and turning of the bottle at specified time intervals. By the end of the riddling process the bottles end up standing on end, caps down. The disgorging of the sediment in the caps is done at almost freezing temperatures, generally after freezing the necks of the bottles. The caps full of sediment are removed, a dosage of sweetener is added and the bottles are topped off with wine to replace any loss in volume, then corked. A brut champagne may have 8 to 12 grams of sugar added per liter, whereas a demi-sec champagne may get 35 to 45 grams per liter.
Since you probably now have more information than you are interested in already, my discussion of wine making will conclude with a brief mention of the bulk process of making more ordinary sparkling wines, or Charmat process. In this case, rather than bottling the wine, the secondary fermentation takes place in large stainless steel pressure tanks.