Production of Sparkling Wines

 Among all styles of wine, the ones who are capable of catching the attention for the charming effect they can create, certainly are sparkling wines. These wines, whose charm mainly derives from the joyous chain of bubbles which develops in the glass as well as from its social prestige, are the result of a complex wine making technique capable of trapping carbon dioxide in the wine - responsible for bubbles and froth - while enhancing its organoleptic complexity. Among the most famous representatives of the wines belonging to this category there is Champagne, certainly the one who was capable of giving this wine the prestige and charm which is repeated every time a bottle of “bubbles” is being uncorked. The production of sparkling wine can be made by using many techniques, each of them having proper qualities and peculiarities and with which can be obtained different results and suited for the many styles of grapes and wines.

 All sparkling wines - no matter the technique used for their production - have a common characteristic: they all are the result of an elaboration made on a “normal” wine and produced according the usual and common wine making techniques. It is then a wine re-elaborated by using specific techniques and that produce as a result, or at least as the most evident result, an effervescent wine. For this reason sparkling wines belong to the category of the so called special wines. The most common sparkling wine types are however produced with a white or rose wine, very rarely with red wines. The reason for which are not produced sparkling wines with red wines - or at least the production is very low - it is to be found in the balance of the finished product. Carbon dioxide - responsible for effervescence - enhances the perception of astringency - which in red wines is practically always present - and therefore the result would be not balanced and scarcely agreeable.

 Just like any other type of wine, the production of sparkling wines begins in the vineyard and by choosing the best grapes suited for the production of this style of wines. Grapes - soon after harvesting - are being pressed and with the must is produced a “still” wine that will be later used for the assembling of a base wine. Base wines used for the production of sparkling wines - in particular non aromatic sparkling wines - are the result of an assemblage, that is of the union of many wines - even of different vintages - having proper characteristics and qualities and however suited to the type of sparkling wine to be produced. A fundamental difference between “regular” wines and sparkling wines is represented by this aspect. Whereas in still wines the finished product is obtained - saved the exception of particular cases - by the must produced with grapes coming from a single harvesting, the base wine for sparkling wines is generally made from tens of different wines - even belonging to different vintages - usually a number from 30 to 60.

	Bottles of Franciacorta on pupitres

 One of the main goals of sparkling wine producers - and in particular for quality sparkling wines - is to ensure a constant recognizability and identifiability of their wines year after year, therefore the assembling of base wine is - as a matter of fact - a fundamental and determinant phase of the production. The base wine - that in French is defined with the famous term cuvée - is prepared by a group of expert and qualified technicians whose job is to analyze the organoleptic qualities of each wine, to choose it for its specific qualities and according to its contribution to the cuvée to be processed and transformed into a sparkling wine. The hard task of these experts is also to imagine the transformation of the organoleptic qualities of the cuvée at the end of the production of the sparkling wine in order to obtain a product which identifies the style of the producer. Wines used for assembling the base wine can also belong to different vintages in case the sparkling wine is not millesimée - also known as sans année or non vintage - whereas for vintage sparkling wines - that is the ones stating the year of vintage in the label - the cuvée can be made only with wines belonging to the same vintage written in the label.

 Wines used for the preparation of the base wine - no matter this could sound strange and paradoxical - do not have organoleptic qualities such to be defined as agreeable. Of course the quality of these wines - in a strictly enological sense - is absolutely equal to the quality of the sparkling wine to be produced, however their gustatory qualities cannot be considered truly agreeable when drunk before the beginning of the sparkling wine making process. The assembling of the cuvée used for the production of sparkling wines is made of pretty neutral wines, very acid and with low alcohol. These wines will be then transformed in a substantial way by the sparkling wine making process - in particular by classic method - not only by adding effervescence but also - and above all - by adding organoleptic complexity, structure and a small quantity of alcohol. Base wines used for the production of rose sparkling wines can be assembled by using a blend of white and red wines - this is the only case where blending these two types of wine is permitted - as well as blending many rose wines usually produced with the bleeding technique (saignée). According to the style and type of sparkling wine to be produced, base wines could also undergo a malolactic fermentation as well as an aging in cask, a practice which is usually used for wines destined to the production of classic method sparkling wines.

 The classic method is the most important system for the production of sparkling wines and with which can be usually obtained the best results in terms of elegance, organoleptic complexity and finesse. This system - also known as metodo tradizionale, metoto classico, méthode Champenoise, méthode traditionnelle or méthode classique, in South Africa méthode Cap Classique - is mainly used with wines produced with non aromatic grapes and in particular with Chardonnay, Pinot Noir, Pinot Meunier and Pinot Blanc. The classic method basically consists is favoring a second fermentation of the wine which is done inside a bottle, a process which is also called bottle refermentation. A particular aspect of this technique is represented by the bottle which accompanies the wine from the moment of the refermentation to the moment of consumption. In other words the bottle containing a classic method sparkling wine is exactly the very same used for the production of that sparkling wine.

 The charming journey of the wine towards the transformation in classic method sparkling wine begins by adding to the cuvée a mixture - made of the same base wine, cane sugar, selected yeast and other substances useful for making the rémuage easier, explained later. In most of the cases are being added 24 grams of sugar per liter (a little less than one ounce) in order to develop a pressure of 6 atmospheres (about 85 psi) to the inside of the bottle (4 grams of sugar develops, during the fermentation, a pressure of about one atmosphere) and for this reason the thickness of bottles to be used for sparkling wines is usually greater in order to prevent their explosion. The wine is then bottled and bottles are capped with special crown caps having a special container - called bidule - which will be useful for keeping the sediments at the end of the fermentation process. Alternatively the bottles can be capped - according to the tradition - with a cork tied to the neck of the bottle by means of a robust metallic clamp. In both cases the closure must ensure an excellent sealing capacity to the internal high pressure of the bottle.

 At this point bottles are laid horizontally in the cellar at a constant temperature of about 10°C (50°F) and in this phase begins the fermentation inside the bottle done by yeast. It is the beginning of the prise de mousse - a phase in which the effervescence begins to form - that is the real and proper refermentation of wine. In this phase carbon dioxide, having no possibility to exit the bottle, remains “trapped” inside therefore creating effervescence. The refermentation process usually lasts one or two months and at the end the alcohol level will be raised of about 1,2 - 1,3%. During the refermentation process bottles are periodically rotated in order to avoid the sediments to stick to the side of the bottle. When the refermentation is over - that is when the sugar has been transformed by yeast into alcohol and carbon dioxide - bottles are allowed to age in the cellar and it is during this slow phase the wine will increase its organoleptic complexity. At this point yeast cells begin to release their aromatic substances to the wine - aminoacids, proteins and volatile compounds - that will enrich the qualities of wine. This process is called autolysis of yeast which usually takes place after eight or ten months from the end of refermentation.

 The amount of time in which the wine is left in contact with the yeast inside the bottle is usually of 15 months for non vintage sparkling wines and of 30 months for vintages, however the best classic method sparkling wines are left in this condition even for ten years and sometimes more. When the producer decides to end the aging of the wine, it is necessary to eliminate the sediment of yeast from the bottle in order to obtain a limpid and presentable wine. Bottles are then placed in special racks called pupitre where qualified personnel shake and rotate the bottles by using a particular technique which favors the gathering of sediments to the neck of the bottle. This procedure is called rémuage and a skilled remueur can also shake 40,000 - 50,000 bottles a day. Despite how much this professional figure can be admired, this procedure is today done by using computer controlled machines called gyropallettes. The automatic procedure of rémuage does not affect the quality of the finished product. The complete procedure of manual rémuage can also lasts six weeks and at the end the bottle on the pupitre is on a vertical position and with the sediment gathered in the neck near the cap.

Manual rémuage in a Franciacorta cellar

 At this point it is necessary to eliminate the sediment in order to have the wine limpid and presentable, a phase which is called dégorgement, or disgorgement. The traditional way consists in uncorking the bottle with a very spectacular gesture - called à la volée - in order to have the internal pressure pushing the sediment out from the bottle. This technique - although spectacular - is scarcely used today because with the expulsion of the sediment is also spilled out a pretty large quantity of wine. The most used technique today is the so called à la glace consisting in plunging the neck of the bottle is a refrigerating brine at a temperature of about -25°C (-13°F) in order to freeze the sediment. The bottle is then turn upside and uncorked, the internal pressure pushes the sediment out and the loss of wine is very low while leaving the content of the bottle perfectly limpid. At this point it is added the so called liqueur d'expédition - liqueur de dosage or simply dosage - having both the function of refilling the bottle as well as defining the level of sweetness of the wine. This mixture is usually made of reserve wines, cane sugar and other “secret” ingredients, typically brandy or other distillates. The exact composition of the liqueur d'expédition is secretly kept by every producer and represents - as a matter of fact - the stylistic mark of every producer. The level of sweetness in sparkling wines is shown in table .

After the liqueur d'expédition has been added, the bottle is capped with a cylindrical cork whose diameter is about twice the one of a regular cork and that will get the usual “mushroom” shape. The cork is then fixed to the neck of the bottle with a wire cage in order to prevent its expulsion because of the internal pressure. The next phase is called poignetage and consists in shaking the bottle in order to perfectly blend the wine with the liqueur d'expédition. After the last check on the limpidity of the sparkling wine inside the bottle - a phase called mirage - bottles are being labeled and after a short period of time spent in the producer's cellars - usually few months - the sparkling wine is now ready to be released in the market.

 This method - which was invented by the Italian Federico Martinotti and French Eugène Charmat - is also called bulk process or Cuvée Close in French. The method is particularly suited for wines produced with aromatic grapes - such as Muscat Blanc and Brachetto - because this method favors the keeping of fresh and fruity aromas of grapes. As opposed to the classic method, it allows the production of sparkling wines within two or three months, however the result is qualitatively lower. A mixture of yeast and sugar is added to the base wine and then it is transferred in a sealed container in which the wine begins the refermentation process. At the end of the refermentation the wine is filtered and then bottled. All these procedures are done in isobaric conditions, that is at the same pressure present in the container in order not to lose any carbon dioxide or effervescence. The Martinotti or Charmat method usually lasts two or three months and in case the wine is left in contact with the yeast for about six months, it is called long Charmat. The quality of these sparkling wines in term of perlage is lower than classic method sparkling wines - a characteristic which is easily recognizable by the greater size of bubbles - and the aromatic complexity of these wines is lower as well.

 There are other methods for making effervescent a wine and of which the most simple one - and less noble - is carbonation, that is the same method used for sparkling water and soda pops. The quality of this method is rather low and it is destined for sparkling wines of very low quality. Another method - usually forbidden for the production of classic method sparkling wines regulated by specific disciplinary - is the so called transfer method. The initial phase is similar to classic method whereas at the moment of rémuage bottles instead of being shaken, are being uncorked and the content is transferred in a pressurized container where the wine is filtered - in order to eliminate sediments - and then bottled. Another method - which is occasionally used for the production of classic method sparkling wines - is called transversage. Soon after disgorgement (dégorgement), the content of bottles is being transferred in a pressurized container and then it is added the dosage. At this point the wine is bottled under pressure and then labeled. This system is generally used for classic method sparkling wines sold in small sized bottles (half bottle and split) or large sizes greater than magnum. For this reason classic method sparkling wines taste better and have a higher quality when sold in regular bottles or in magnums, that is the very same bottles in which they have been made.