Copyright 1999
Chapter 20
MAKING SPARKLING WINE
Sparkling wines are produced in France, Spain, Italy, etc., but only those sparkling wines made in a small region of France using the classical method is called Champagne. Sparklers produced anywhere else are properly called "sparkling wines."
Sparkling wines are blended from several carefully selected lots of still wine, and the French word for the batch of starting wine used to make Champagne is "Cuvee." Classical sparkling wines are made by applying a multi step process to the blended, still wine. A second sugar fermentation takes place in the bottle, and this fermentation produces a carefully controlled volume of carbon dioxide gas and a small amount of ethyl alcohol. The carbon dioxide gas produces the desired effervescence. The small quantity of additional alcohol is of little consequence.
Four steps are used to produce traditional sparkling wine. (1) First, sugar and yeast are added to a finished still wine, and the wine is bottled. (2) Fermentation converts the added sugar into alcohol and carbon dioxide gas. (3) The new sparkling wine is aged on the yeast lees for a year or more. (4) After aging, the sparkling wine is "finished." During finishing, upside-down bottles are turned repeatedly to work the yeast lees down onto the bottle caps. After several weeks of turning, when the yeast is on the caps, the yeast lees are "disgorged" from the bottles. Any wine lost in disgorging is replaced with a small quantity of still wine containing sugar, and the bottles are corked.
Novice winemakers may find this process complex, but the whole procedure becomes relatively simple when each step is understood. Nevertheless, the production of traditional sparkling wine is by necessity a lengthy and labor intensive process. The quality of sparkling wine is determined primarily by the starting cuvee, and by the length of time the wine is aged on the yeast lees. Long aging times and extensive handling are required to produce a quality product. The considerable time and effort required to produce quality sparkling wine accounts for its high cost.
CUVEE
Finished sparkling wine quality depends largely on the characteristics of the starting cuvee, and the starting wine should have several specific characteristics. The starting wine must be dry, or if it contains sugar, the quantity of the sugar must be accurately known. Cuvee should have a clean, neutral bouquet, and any varietal flavors should be subtle. Cuvee has a high acid content, and the titratable acid often falls between 0.7 and 0.9 percent. In addition, the starting wine should be low in free sulfur dioxide (less than 25 milligrams per liter), and the alcohol content should be between 10 and 11.5 percent.
Grapes harvested specifically for making sparkling wines are picked before they are completely ripe, and the sugar content is only 17 to 20 Brix. Early picking helps insure subtle varietal flavors and a high acid level. Early harvested grapes also produce a starting cuvee with a low alcohol content, and the low alcohol makes the second fermentation easier to start.
In the Champagne region of France, cuvee is made from about 2/3 Pinot Noir grapes and about 1/3 Chardonnay grapes. Chardonnay is a white grape, but Pinot Noir is a red grape. Most red grapes have colorless juice. The color is in the grape skins. Since the red color is in the skins, red grapes must be handled gently and pressed quickly to avoid introducing a blush color into the cuvee. In California, high quality "blanc de blanc" cuvee is often blended from wines made from Chardonnay and Pinot Blanc grapes. In Italy, the famous "Asti Spumante" sparkling wine is made entirely from White Muscat grapes.
Blending Cuvee
Sparkling wine cuvee must be clean, stable and brilliantly clear. Home winemakers often produce a satisfactory cuvee by blending and modifying available dry white wines. Generally, the alcohol content will be too high when white table wines are used, and flavor levels are often to intense. However, the blend can be diluted with a small amount of water. Often a 10 percent water addition will reduce the alcohol content too less than 11.5 percent and dilute flavor intensities as well.
The titratable acid and the free sulfur dioxide content of the cuvee will also need adjusting. Most available table wines will require modest additions of acid to raise the TA to about 0.80 percent. Large additions of tartaric acid should be avoided, or the wine may need to be cold stabilized again. Citric acid is often used for small acid adjustments because it does not produce instability problems.
The second fermentation in the bottle will be very difficult to start if the sulfur dioxide content of the starting wine is too high. When the free sulfur dioxide content exceeds 25 milligrams per liter, hydrogen peroxide can be used. An addition of 3.5 milliliters of 3% hydrogen peroxide in 5 gallons of wine will remove 10 milligrams per liter of free sulfur dioxide. Wine flavors or aromas are not affected significantly when hydrogen peroxide is used properly. However, hydrogen peroxide is a potent, oxidizing agent. Bench testing should be done when using hydrogen peroxide, and accurate sulfur dioxide measurements are necessary.
Measuring the Sugar
The total sugar content of the cuvee must be very carefully controlled. If the sugar content is too low, the finished wine will not have enough effervescence. However, if the sugar content is too high, excessive pressures will be generated in the bottle, and excessive pressures can cause the bottles to explode. When commercial sparkling wines are made, enough sugar is added to produce bottle pressures of about 90 pounds per square inch (psi). However, home winemakers are strongly advised to work with less pressure. Exploding bottles are the subject of jokes, but they can be serious hazards.
One and one-half (1.5) ounces of sugar for each gallon of completely dry wine is recommended. This quantity of sugar will produce a lively sparkle in the finished wine, and bottle pressures will be held to about 40 psi. Ordinary white, granulated household sugar should be used. The starting wine must be completely dry, and the residual sugar should be measured with a Clinitest tablet. The quantity of sugar must be accurately weighed, and the volume of the cuvee accurately measured. Do not guess at any of these quantities.
The carefully measured sugar and a small amount of yeast nutrient should be added to the wine. About 1/4 tsp. of diammonium phosphate in 5 gallons of wine is the right amount. Then the cuvee should be stirred until all of the sugar and DAP are dissolved.
SECONDARY FERMENTATION
Starting the second fermentation is very much like starting a stuck wine. The process is quite simple, but considerable attention by the winemaker is required. First, a pint of starter is made from dry yeast and a spoonful of sugar. Prise de Mousse or California Champagne yeast should be used. These yeasts are tolerant to both alcohol and sulfur dioxide. Despite its name, Pasteur Champagne yeast is not very good for sparkling wine production. This yeast will ferment satisfactorily, but Pasteur Champagne yeast lees are difficult to riddle.
When the starter is active, an equal volume of cuvee is added to the starter, and the quart of starter is set aside. Wait until the starter becomes active again, then add a quart of cuvee. When the starter is again active, two quarts of cuvee is added. This doubling process is continued until the entire batch of cuvee shows signs of active fermentation. The doubling process can be accomplished in twenty-four hours or so if the starter is kept warm. Low temperatures will require more time. The cuvee is ready to bottle when a ring of fine bubbles appears around the edge of the container, or when the winemaker observes other signs of fermentation.
The starting wine must be bottled in Champagne type bottles. Do not use other kinds of bottles. The pressures are much too high. Each bottle should be cleaned and inspected carefully, and any bottles with scratches, chips or cracks should be discarded.
Clean, sound bottles should be filled until the head space is about two inches. All domestic champagne bottles are made with a special lip that allows the bottles to be closed with "crown" (beer) caps. Crown caps should be used to seal the bottles rather than corks. Caps are less expensive, and they are much easier to remove later. Caps can be quickly and easily applied with a small, hand capping machine.
AGING
Much of the desired character of sparkling wine is derived from the wine being in contact with the yeast lees for an extended time. Yeast contact time is very important, and a high quality product cannot be produced quickly. In France, all Champagnes must spend at least one year on the yeast lees or the word "Champagne" cannot be placed on the label. All high quality sparklers spend from one to four years on the yeast lees. Some home winemakers produce a three or even four years supply of sparkling wine in a single batch. Making a large batch every three or four years is a good technique. Some wine is available to drink after a year, but much of the sparkling wine can be aged for an extended time.
Sparkling wine should be aged in a cool, dark environment free from excessive vibration. The bottles can be laid on their sides and stacked up like fire wood. When the bottles are stacked this way, the yeast lees are spread over a large surface area, and the large surface area is an advantage. However, if adequate space is not available, the wine can be stored in cardboard cartons with the bottles standing vertically with the points up. In either case, the bottles should be shaken gently every six months to agitate the yeast sediment back into suspension. Considerable care, leather gloves and safety glasses are appropriate for the shaking procedure.
THE FINISHING PROCESS
Sparkling wine is ready to finish after it has aged on the yeast lees for an appropriate time. Finishing a sparkling wine consists of three basic steps. (1) First, the yeast lees are induced to slide down the side of the bottle until all of the lees rest on the crown cap by riddling. (2) The yeast lees are removed from the bottle by disgorging. (3) Finally, the new sparkling wine is sweetened to the desired level, and the bottle is corked.
Riddling
When aging is complete, the next step is to remove the yeast lees from the bottle. Riddling is the name of the process used to move the yeast sediment down onto the crown caps. Traditionally, large wooden racks were used to hold the bottles in a slanted position with their points down, and each bottle was rotated about an eighth of a turn each day. Traditional wood riddling racks are heavy, and considerable space is needed when these racks are used.
Fortunately, other techniques have been developed to coax the yeast down the side of the bottle onto the crown cap. A simple method of riddling consists of placing the bottles in ordinary cardboard cartons with their points down. Then each day the bottles are jostled, bumped or twisted. Early in the process, the cartons are propped over at an angle. Later, after the yeast has started to move down the side of the bottle, the cartons are moved to a more vertical position.
The riddling process is strongly influenced by the type of yeast used and the cleanliness of the bottles. Usually six or eight weeks are needed to complete the riddling operation. However, under adverse conditions, three or four months may be required. If the bottles were not scrupulously clean, sparkling wine can be almost impossible to riddle.
Disgorging
Since small producers often work with a minimum of equipment, removing the yeast sediment from the bottle is often the most difficult step in the sparkling winemaking process. The objective of the disgorging operation is to remove all of the yeast from the bottle without reducing the carbon dioxide pressure significantly.
The classical method of removing the yeast is a multi step process. (1) The bottles are chilled with their points down until the temperature of the wine is less than 45 degrees. (2) The necks of the bottles are placed in a cold brine solution until a plug of ice an inch or so long freezes in the necks of the bottles. (3) The bottles are removed from the brine solution, and the necks of the bottles are dipped in clean, room-temperature water. (4) After the brine has been washed away, the necks of the bottles are raised to a 45-degree angle, and the crown caps are removed quickly. (5) The plugs of ice flies from the bottles, and the ice carries most of the yeast sediment away. (6) The winemaker's left thumb is judiciously applied to each bottle to control gushing. If the wine is cold and if the bottles were clean, gushing quickly subsides. (7) The winemaker then uses the little finger on his right hand to wipe away any remaining yeast from the inside surfaces of the mouths of the bottles.
A written description of this process sounds complicated, but after a few bottles have been disgorged, the whole procedure becomes quite simple, and the work progress rapidly.
Sweetening and Corking
Most people prefer off-dry sparklers, and wines containing 1 to 4 percent residual sugar are common. The desired level of sugar is introduced by adding a small dose of syrup to each bottle after the yeast has been removed. This syrup also contains a small amount of sulfur dioxide to help preserve the sparkling wine. The syrup is made up ahead of time, and the syrup must be well chilled before it is added to the disgorged bottles.
A typical syrup contains 375 grams of sugar, one gram of sulfite powder and 700 ml liters of dry white wine. When 30 ml of this syrup is added to a standard 750-ml bottle, the finished sparkling wine will contain about 2 percent sugar and about 30 milligrams per liter sulfur dioxide. Of course, the sugar and SO2 can be adjusted to any desired level.
Syrup should be added to the bottles after any remaining yeast has been wiped away. Each bottle is tipped to a 60-degree angle, so the syrup runs down the inside surface of the bottle. The syrup must be cold, and it must be added slowly and continuously to avoid gushing. After the syrup has been added, the liquid level in the bottle should be adjusted by adding wine from a reserved bottle of cold sparkling wine. When the head space is correct, the bottle can be sealed with a polyethylene stopper, and a wire hood should be attached to hold the stopper in place. After all the bottles are sealed, the outside surfaces should be rinsed clean with cold water. Then the bottles can be set aside to dry, and labels can be applied after the bottles reach room temperature. New sparkling wines should be allowed to rest for a few weeks in a cool, quiet place to recover from bottle shock. After a short rest, the sparkling wine will be ready to use. Sparkling wines usually keep well, but after the yeast has been removed, the wine will show little improvement with further aging.
SUMMARY
Sparkling wine is made by adding sugar and yeast to a still wine, and the wine is tightly sealed in bottles specially designed to withstand high pressures. A second fermentation takes place in the bottle, and the carbon dioxide gas produced gives the wine the desired effervescence.
Quality sparkling wine is aged on the yeast lees for a year or more. Then the wine is ready to finish. The yeast is worked down the side of the bottle until all the sediment rests on the cap, and then the yeast is expelled from the bottle. The wine is then sweetened with syrup, and the bottle is sealed with a polyethylene stopper.
The starting wine must be dry, and the added sugar must be measured carefully. Only sound Champagne type bottles can be used for making sparkling wine.
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