Winegrowers Supplies  -  Making Quality Sparkling Wine (by the méthode Champenoise)

1) Pressing:

   It is usual to press whole bunches, without crushing or de-stemming, to extract the juice without maceration of the fruit; resulting in a wine with less grapey flavours. With a horizontal press, use a maximum of 1.5 bar pressure and rotate the press-cage with as few rotations as possible; or use a large vertical press.
   In Champagne the best quality 'Cuvée' is restricted to the first 510 litres of juice per tonne of grapes (51 % 'extraction'). The maximum extraction should be 66 %, although I have never reached this %; the extra 15 % is the 'press fraction'.

   The amount of berry-botrytis infection must be well below 5 %; since the low sulphur dioxide level used throughout the winemaking will not restrict laccase activity. Selective picking may be necessary to achieve this.
   SO2 can be added at 4 (up to 10) grams per 100 litres, although it is better to avoid this by careful selection of the grapes.
   It is particularly important that care is taken to minimise oxidation, throughout the winemaking process. Pinot Gris and Freisamer are especially prone to oxidation.

   Immediately after pressing: measure the volume of must in the holding tank.

   Add 'white wine' pectolytic enzymes (to improve clearing etc): 3 ml to 5 ml of Erbslöh Trenolin per 100 litres of must.

   Leave for 12 - 24 hrs to settle.

2) Next day:

a) Measure the acidity of the must with a test such as the Sulfacor. The measurement gives the 'tartaric equivalent' acidity.

   If acidity is above 12 g/l then de-acidify with Neoanticid down to 12 g/l (or 11.5 g/l if not a classic variety); the desirable acidity of the must is in the range 10.5 to 12.5 g/l; de-acidification procedure.

   If no de-acidification is necessary then simply rack off the clear must into a clean tank, then use Trub-ex to clarify the cloudy must remaining in the bottom of the holding tank, adding this clarified must to the rest of the clear must.

   Ideally the suspended solids should be very low indeed (less than 0.2 grams per litre).
Settling/racking ('débourbage') can be followed by coarse filtration, if necessary, to further clarify the juice.

b) Measure the specific gravity (°Oechsle) of the clear must, with a must refractometer (or must hydrometer and trial jar).

   Calculate the predicted 'natural' alcohol of the must.
   Add granulated sugar (beet sugar is thought preferable to cane sugar for Sparkling wine) to increase 'total' alcohol ideally to 10.5 %vol (the minimum allowed for Quality Sparkling Wine by EC regulations is 9.5 %vol); enrichment procedure.

   Add yeast nutrients; should be added before the addition of the yeast.

   Rehydrate the selected yeast: rehydration procedure.
   Add to the must, rouse and leave to ferment (primary fermentation).

3) After the end of primary fermentation:

   Sodium bentonite can be added, to remove excess protein; it also assists in colour removal with Pinot Noir.

4) Racking: about 8 to 10 days after the addition of bentonite:

   Normally racking is carried out through the flap-valve. If a tank is without a man-way door it is possible to rack off through the bottom outlet of the tank, although this is not normal practice; if the yeast-lees are compact enough only a small amount of lees is carried through. The first litre or so can be run off into a large jug or bucket, the juice from this can then be poured into the receiving tank leaving the solid sediment to be discarded.

   It is particularly important to minimise the aeration which occurs when racking; make sure there is no leak on the suction side of the pump. The colder the temperature the more oxygen the wine can dissolve (leading eventually to greater oxidation).
   Each racking will reduce the ultimate quality of the wine, so plan to rack only the minimum number of times necessary (once only if possible).

   Pump into the bottom inlet of the receiving tank (clean and sterile); if using a variable capacity tank put the floating lid inside (with pneumatic seal deflated, and any cooling plates removed) so that it rides up with the wine.

   Before starting to rack, take a sample of the wine and measure the level of free SO2 with a test such as the Sulfacor.

   Calculate the amount of wine sulphur needed to raise the free SO2 to 17 mg/litre.
Put the calculated amount of wine sulphur into the receiving tank before starting to rack.

5) Cold stabilisation:  in January/February:

   Once sufficient time has gone by and low enough temperatures have achieved tartrate stability (excess tartrate has precipitated on the walls of the tank). A cold room can be used to facilitate this.
   The level of free SO2 should be as low as possible, less than 20 mg/litre.

   Acidification of the base wine is permitted by up to 1.5 grams per litre (expressed as tartaric). Acidifying the wine with tartaric acid may affect the tartrate stability, so if this is done the wine should be left for a further period of cold stabilisation.
The desirable acidity for the base wine is 10 to 11 grams/litre with a pH of between 2.9 and 3.3.

6) Clarifying ('collage', fining): with gelatine, or a coarse (or sterile) filtration:

Preparation for secondary fermentation in bottle:

7) Sugar addition ('liqueur de tirage'):

   Addition of beet sugar at 23 to 26 grams/litre, depending on the alcohol content and pressure required; the higher the alcohol and the greater the pressure required, the more sugar needs to be added.  
For base wine with between 9 % and 12 % alc by volume, with pH between 2.9 and 3.3:-

Alc %vol.       Sugar (grams/litre) to obtain:

                    5.0 bar      5.5 bar      6.0 bar

    9                 19             21            23

   10                20             22            24  **

   11                21             23            25  **

   12                22             24            26

The normal pressure in bottle-fermented sparkling wine is approximately 6 atmospheres (5.9 bar, 88 psi) which is equivalent to 8.4 grams/litre of CO2 at 20 °C.

   A further consideration is that under EC regulations the maximum allowed at this stage is 1.5 % increase in alcohol. The Wine Standards Branch of the Food Standards Agency specifies 16.5 grams of sugar per litre as = 1 % increase in alcohol by volume, although this differs from French, Australian and German figures of 17.0, 16.95 and 16.85 g/l.
   16.5 x 1.5 equates to 24.75 grams of sugar per litre of wine; although 16.85 g/l is considered to be the most accurate figure: 16.85 x 1.5 = 25.27 g/l, maximum addition.

   It is very important to rouse continually while any sugar is being added, else the sugar may form a solid lump on the tank bottom, instead of being dissolved in the wine.

8) Addition of yeast nutrients:

   Since the primary fermentation reduces the quantity of yeast nutrients in the wine, it is important to add 5 to 20 grams per 100 litres of diammonium phosphate. Combined yeast nutrients are normally used, although there is usually sufficient thiamin present, so it is cheaper to add only diammonium phosphate. It should be added before the addition of the yeast.

9) Yeast rehydration and addition ('levurage'):

   Use a selected 'active dry wine yeast' of the species Saccharomyces bayanus; following the rehydration procedure.

   If the base wine is heated to above 15 °C it is possible to add the rehydrated yeast directly to the wine; making sure of really good mixing by rousing thoroughly.
After adding the yeast, 24 hours should be allowed for the yeast to multiply, before filling the bottles.

   Alternatively, especially at lower temperatures, a process of acclimatisation is recommended:-
10% volume of the base wine is drawn off and 5 % of the total sugar requirement is mixed in. The necessary yeast quantity for the complete volume is then rehydrated as above and added to this separate 10 %, at around 20 °C.
The fermentation is allowed to progress until around half of the available sugar has been fermented. This pre-culture is then mixed thoroughly with the other 90 % of the base wine, just prior to bottling.

10) Addition of a riddling aid:

    Riddling aids comprise sodium bentonite (3 to 8 grams per 100 litres), isinglass (0.5 to 6 grams per 100 litres), alginate (0.5 to 2.5 grams per 100 litres), tannin (0.5 to 5 grams per 100 litres) in some combination. A proprietory product such as Sekt-Klar (50 to 70 ml per 100 litres) can be used. Continuous rousing before and during bottling is required to assure an even distribution.

11) Bottling ('tirage'):

   Rinse the inside of the sparkling wine bottles with sterile water and put the bottles on a 'tree' to drain. It is not normally necessary to sterilise the bottles before rinsing as the subsequent fermentation process will achieve this.

   Fill the bottles; to about 30 mm below the fill height embossed on the bottom of the bottle, in order to allow sufficient space for the substantial increase in volume that occurs during secondary fermentation. Then seal with a crown cap.

   If bottling has been carried out immediately after adding the yeast, the filled bottles should be kept initially in a room at above 15 °C so as to assist the start of fermentation.

12) Stacking ('entreillage'):

   The bottles are then put away for fermentation and storage on the yeast deposit. They may be stacked horizontally or vertically.

   The secondary fermentation usually takes place at between 11 °C and 16 °C in Australia, or 11 °C and 14 °C in Champagne. It lasts for 4 to 6 weeks according to temperature; it is necessary for fermentation to go to dryness, the alcohol produced in yielding 8 g/l of CO2 is 1.0 % by volume.

   EC regulations are that there shall be a minimum time of 9 months 'on the yeast'.

   Ideally, the bottles should be taken out and shaken up after 6 months in storage (or after 12 months if the storage period is 3 years).

   After the second fermentation has ended, the dead yeast cells break down by autolysis. This usually lasts for 4 to 5 years, but can last longer. The compounds that are released have anti-oxidative properties, and protect the wine during this period. Amino-acids and other nitrogenous compounds are released. These contribute to the finesse. Acetal compounds that are produced contribute 'biscuity' flavours. The duration of maturation in the bottle will affect these flavours.

13) Riddling ('remuage'):

   After 9 months or preferably much longer, when the bottles are ready for yeast removal, various methods may be used to shake the yeast down on to the crown cap of the inverted bottle. Oak pupitres are the traditional means, turning the bottles by hand. Using a gyropalette is a much faster and easier method taking only 7 days.

   Procedure for using a pupitre: remove the bottles that have been stored horizontally ('sur lattes') and give them a quick shake (called 'poignetage'). If the bottles have been laid down for many years since bottling then the lees, which will have settled on the side of the bottle, may stick. This initial shake should dislodge the sediment.
Then insert the bottles into the pupitre; termed 'pointage'. The bottles are inserted almost horizontally, and then given one twist each day for between 21 and 28 days, according to how much the lees stick to the bottle; riddling aids should avoid too much sticking. The twist given must be sharp enough to make the sediment slide down towards the neck of the bottle, but not vigorous enough to make it rise up in a cloud into the wine.
The first twist is about one eighth of the circumference, on subsequent days the bottles are given quarter turns. Two bottles are turned simultaneously, one gripped in each hand. With each twist the bottles are moved very slightly towards the vertical.
It's best to start by turning a horizontal row of four bottles at the top of the pupitre, then work down to the bottom row; this is faster than turning a complete row of bottles at a time.

14) Removal of sediment by disgorging ('dégorgement'):

   After the riddling operation is complete, with the bottles now upside down, the next step is to expell the solid particles that are just inside the bottle neck.
A 'neck freezer' is used, designed to cool the temperature of the wine in the bottle neck to obtain a solid ice piece. The cooling liquid is non-toxic ethylene or propylene glycol, mixed with water 50% + 50%.

   Once the neck is frozen it is necessary to tilt the bottle at the correct angle before flipping off the crown cap. You need to let the CO2-bubble inside the bottle ride up its shoulder. The position of the bubble is crucial in ensuring that the pressure expells the bidule and lees cleanly. If it's done wrongly then some of the lees can be absorbed back into the wine, in which case there is no choice but to re-cap the bottle and do the riddling all over again.

15) Sweetening ('dosage') and topping up ('remplissage'):

   The 'liquer d'expidition' is a product added to sparkling wine to give it special taste qualities. It may contain only:-
sugar (sucrose),
grape must, or grape must in fermentation,
concentrated grape must, rectified concentrated grape must,
wine,
or a mixture thereof, with the possible addition of wine distillate (brandy).

   The addition of expedition liqueur must not increase the actual alcoholic strength by more than 0.5 % vol.
There are machines that combine dosage with disgorging.

16) Corking ('bourbage'):

   Large diameter corks are used, which are compressed into the 'mushroom' shape with a special corking machine. Pneumatic machines are normally used, hand-operated corkers are much cheaper but hard work.

17) Wire muzzling ('muselet'):

   A special wire muzzling machine is necessary to twist and tighten the wire muselet.

18) Shaking:

   To mix the viscous expedition liqueur with the wine.

19) Washing:

   To clean the outside of the bottles.

20) Dressing ('habillage'):

   Placing the foil capsule over the bottle and pleating it in position (with a pneumatic foil-pleating machine) then labelling.

21) Maturation:

   After disgorgement, Sparkling wine bottles really need to be laid down for at least 6 months before they are sold, as further changes occur in the bottle. These changes are judged to involve an increase in 'biscuity' or 'toasty' qualities. These result from the 'reaction Maillard' between nitrogenous compounds and sugars. The taste of an old vintage may therefore depend on what proportion of its time in bottle has been spent before or after disgorgement.
Upon disgorgement it becomes more sensitive to oxidation with age, so older-disgorged bottles tend to age faster. The taste of an older vintage may be influenced just as much by the date of disgorgement relative to the vintage as by the quality of the vintage. This has led to some controversy about the relative desirability of early versus late disgorgement. Some Champagne houses believe in disgorgement relatively soon before the bottle is sold, led by Bollinger (whose prestige R. D. cuvée indicates Recently Disgorged). There are ideas for showing the date of disgorgement on the bottle, so the consumer can judge.

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