4. Analysis of the characteristics of the wine from each growth
 

      The final step in wine making is blending, or the combination of several wines. This process aims to provide the consumer with the consistent taste they expect in a brand. It is a delicate phase evoking the notion of a great orchestra, with each soloist playing his part, bringing his own qualities to achieve the perfect performance.
      Nonetheless, before they are joined, each soloist must work independently to define his own identity. The grape juice undergoes this process between October and December. During these three months, the different juices (cuvée and taille) will evolve and become more refined in advance of the final blending. All of this of course takes place under the watchful eye of the wine maker. 
 

1) The 'chaptalisation'

      If, after the fermentation, the wine does not contain enough alcohol, the wine maker will undertake a process known as chaptalisation. This consists of adding either sucrose (beet or cane sugar) or a concentrate of rectified must (concentrated liqueur of grape sugar) to the wine.

      In this way, the wine maker intervenes to ensure the best possible fermentation and produce a wine with an alcohol content between 10.5° and 11.5°. These levels must not be exceeded in order to comply with the current legislation which allows a maximum alcohol content of 13° for sale. This takes into account the increase of 1.2-1.3° during the "creation of the sparkle". On the other hand, it is necessary that these levels are not lower either as they enable the fixing and encourage the appearance of secondary aromas.

      Chaptalisation is sometimes unnecessary during exceptionally sunny years when the grape can reach full maturity. 

      The natural acidity of the grape juice must be preserved or even increased to allow it sufficient ability to age. The natural acidity is amended by natural oenological procedures, such as 'malolactique' fermentation, which turns malic acid into lactic acid through a perfectly natural process.

      There are several different species of fermentation agents (or indigenous yeast) in the grape skin, all of which have different qualities. To conserve both the quality and the specificity of each wine, it is vital that the majority of yeast strains contribute towards the best possible production. This explains why natural yeast (selected and multiplied) is added to the vats of must. This process is known as 'yeasting' (or yeast addition).

      The most frequently used strain is developed by the CIVC technical services and marketed by a group of oenological laboratories. These strains, scientifically known as 'Sacchaomyces cerevisiae', are used either directly with a dose of 10 to 20 g/hl after re-hydration in the must, or through the intermediary of a starter yeast prepared in reserved wine. Some important Houses (e.g. Moët & Chandon) create their own strains of selected yeast.

     This first phase in the production of a wine lets us observe two natural phenomena. In the end we obtain a 'still' wine (natural/clear), which is a non-sparkling white wine from Champagne, with the same appearance as a Chablis, an Alsace or a Muscadet.

      - the first phenomenon is biological. It is the alcoholic fermentation resulting from the natural transformation of grape sugar into alcohol.

      - the second is physico-chemical. This finishes with the clarification of the wine after the alcoholic fermentation.

      These two phases will now be presented in further detail.

Primary fermentation

Vidéo 1'05 min

B) The Alcoholic Fermentation   

      Alcoholic fermentation, observed and used for a very long time, only found a rational explanation in the middle of the 19th century, with the work undertaken by Louis Pasteur. He was the first to demonstrate that it was not due to the action of air on the sugar, but rather to the presence of micro-organisms, notably the yeast carried by the wind and the insects. We will now take a look at this process.

      The enzymes contained in the yeast break down into ethyl alcohol, carbon dioxide and secondary products such as natural sugars (glucose and levulose) and any sugar eventually added. This chemical reaction, which can be defined as a natural biological phenomenon, lasts for around fifteen days and is accompanied by the production of great heat.

      In 1815, Louis-Joseph Gay-Lussac posed the following equation: "One molecule of sugar gives two molecules of ethyl alcohol and two molecules of carbon dioxide, as well as a strong emission of heat".

Applied to wine, it is written as: "C6 H12 O6 + yeast ---------> 2 C2 H6 OH + 2 CO2 + Q".

      In 1860, Pasteur demonstrated that this reaction is only viable for about 95% of transformed sugar and that secondary products are formed from the remaining 5% - glycerol, superior alcohol, lactic acid, acetic acid and succinic acid and superior esters.

		For a long time, the alcoholic fermentation of the must took place in wooden casks or tuns, in glassed cement or enamelled steel vats. Today, it takes place in temperature controlled, stainless steel vats containing 50 to 1,000hl.
Tun room				Thermo-regulated vat room

      During the first five or six days the fermentation takes the form of effervescent grape juice, which gives the impression of boiling - giving rise to the expression 'bouillage' (boiling) used by wine makers. This whirlpool is provoked by the large quantities of carbon dioxide bubbles, which rise up from the fermenting lees to the opening. These bubbles carry with them solid particles forming an notable quantity of foam. It is essential therefore that an appropriate space must be left when filling the containers

      The wine maker then uses different techniques to control the temperature (cooling down the room, running water, circulating a refrigerating liquid, etc). He must constantly maintain a temperature of 16 to 20° C to encourage regular fermentation without evaporating the aromas. It eventually calms down and the transformation of the last grams of sugar finishes within a fortnight. The volume of the vats is topped up with a supply of the same wine, which is known as 'ouillage' (topping-up).

The follow-up to the fermentation is carried out daily with measurements of density and temperature. One must also oversee the release of carbon dioxide.       The alcohol transforms the liquid into wine with an alcohol content from 7° to 7.5° for the appellation.       At the end of the fermentation, the wines are either left on their lees to undergo a new fermentation, known as the malolactic fermentation, or racked and clarified.
		Fermenting room of Piper and Charles Heidsieck

 
C) The malolactic fermentation

      The malolactic fermentation, or 'malolactic retrogradation' became widely used in Champagne from the 1950s onwards, with the standard use of fermentation vats.

      This is a biological process, which transforms, through bacterial means, the malic acid of the wine into lactic acid with an emission of carbon dioxide. This operation greatly reduces the acidity of the wine. This is due to the fact that malic acid is a diacid with two acidic functions, while lactic acid only has one. There is, therefore, a retrogradation of malic acid by decarboxylation of one of its functions. The chemical equation is as follows :

"(COOH)² - CH2 - CHOH --------> CO2 + CH3 - CHOH - COOH"

      For a long time, this second fermentation was poorly controlled. It started just after the alcoholic fermentation, was suspended by the first cold weather of winter, and then restarted as soon as the temperature rose. If the wine was already bottled, it became 'petillant'. It was said to be 'working'.

      The wine maker now manages this phenomenon quite well. After the alcoholic fermentation, he knows how to maintain the wine at a minimum temperature of 18 to 20° C. He proceeds with bacterial inoculations based on lyophilised Leuconostoc oenos coming either from batches, which have already undergone this fermentation or from an intentionally developed culture.

      The activity during the malolactic fermentation is less intense and less visible, but lasts much longer than the alcoholic fermentation and requires from four to six weeks. This fermentation gives a wine less acidity, more suppleness, refined aromas and ensures a great future stability.

      On the other hand, wines that have kept their malic acid are fresher, more acidic and fruitier. They keep for longer. These wines can survive for years without showing signs of age.

      Once the alcoholic and malolactic fermentations have taken place, the wine is progressively chilled to 10 or 12° C. At this point it needs to be clarified.

D) Different clarification procedures

      The action of yeast on the must creates a deposit of lees formed from both the last organic waste and the tartaric crystals at the bottom of the fermentation vats.

      Before any other operations, it is now necessary to carry out a test of exposure to air on the wine for 48 hours. This is to check that it neither oxidises nor browns. Next, an initial tasting takes place to detect any eventual 'false taste' and to appreciate the colour. When all these tests are positive, a first racking takes place in November-December in order to separate the new wine from the fermentation lees. Subsequently these are sent to the distillery to make alcohol ('fine de Champagne').

      Once racked, the wine is still opalescent because of the material held in suspension. This explains why it must be clarified using one of the three following technical processes:

- Fining

      This very ancient practice goes back to Roman times. It consists of introducing a quantity of exogenous substances, such as egg white, into the wine. In modern times, casein (milk powder) is frequently used. These protein compounds characteristically coagulate when in contact with tannins. In this way, they carry the solid particles held in suspension in the wine towards the bottom of the vat. This generally takes 10 to 15 day

- Filtration

      The filtration can either perfect the fining or replace it. It consists of passing the wine through a porous mass in order to remove any undesirable particles through two simultaneous techniques - straining and absorption. Four different processes can be identified.

- Centrifugation

      The leftover material held in suspension is accelerated when it takes place under the constraint of centrifugal force. The classic centrifuges (5-8,000 times gravity) and high performance models (14-15,000 times gravity) give excellent results in a very short time period. They are programmed to preserve the limpidity of the wine.

            The filtration and centrifugation stages have the advantage of speed, but they do require expensive equipment.

      Once this phase is completed, each wine has reached a certain level of maturity. As we mentioned earlier, each of the soloists is now ready. It is effectively from this moment onwards that the specific tasks for the Champagne wine start. Although Champagne can be produced with the grapes from one single growth, it is more frequently the fruit of a selection of wines coming from several growths, grape-varieties and years. It is this craft of union and harmonisation that ensures a consistent taste over the years. This phase, known as blending, must combine the different growths into a harmonious choir producing the perfect concert.