Sparkling wine, epitomized by Champagne, is an indispensable element at parties and other festive occasions. Have you ever wondered how this effervescent wine containing carbon dioxide gas is actually produced?
While explanations of production methods are commonly available, Japanese articles that systematically explain the specific process flow are surprisingly scarce. Understanding the specific production methods makes it easier to appreciate the characteristics of sparkling wines made using different techniques.
Therefore, this article will organize the processes of each production method while explaining the characteristics and differences that arise from them.
For a general overview of production methods, please refer to the article "Various Types of Sparkling Wine," and for regulations on sweetness levels in German sparkling wines, see "Is 'Trocken' in Sparkling Wine Dry?". Please use these as additional references.
Important Note on Content
Unless otherwise specified, the aging periods and various conditions described for each production method are based on German wine law.
Production Methods and Types of Sparkling Wine
Sparkling wines have several different production methods depending on their type.
For example, Champagne, which is highly popular in Japan, must be produced using the bottle fermentation method (also called the traditional bottle fermentation method).
While the various production methods may seem confusing as they branch into multiple categories, there is only one key point to understand initially: how the "bubbles" are created. This can be broadly divided into two methods.
Methods for Creating Bubbles in Wine
- Method of creating "bubbles" by injecting carbon dioxide gas (carbon dioxide injection method)
- Method of creating "bubbles" through "fermentation" (secondary fermentation method)
The first method involves injecting carbon dioxide gas into regular wine (called still wine) to create sparkling wine. Think of the popular home carbonation machines (soda makers) for an easy comparison. Sparkling wines called Secco and Perlwein are made using this method.
In contrast, the second method creates sparkling wine using carbon dioxide gas produced during fermentation, without adding external carbon dioxide.
The still wine used as the raw material for sparkling wine has already completed alcoholic fermentation once to become wine. Since this wine undergoes fermentation a second time to produce carbon dioxide gas, this method is called the secondary fermentation method.
Classification of Secondary Fermentation Methods
The secondary fermentation method also has two approaches. The difference between these two methods lies in the "location" where the second fermentation takes place.
Two Methods of Secondary Fermentation
- Tank secondary fermentation method (Charmat method)
- Bottle secondary fermentation method
The method of conducting the second fermentation in tanks is called the tank secondary fermentation method or Charmat method. In contrast, the method of conducting the second fermentation in bottles is called the bottle secondary fermentation method.
Sparkling wines made using the Charmat method include Italian Spumante, German Sekt, and Schaumwein.
The bottle secondary fermentation method, world-famous as the Champagne production technique, is used for almost all premium sparkling wines produced worldwide. This bottle secondary fermentation method also has two variations.
The difference lies in whether the wine is removed from the bottle after fermentation or not.
Two Methods of Bottle Secondary Fermentation
- Complete bottle secondary fermentation method
- Tank transfer method (Transvasage method/Transfer method)
The complete bottle secondary fermentation method, also called the traditional method, involves bottling the still wine for second fermentation and then proceeding to shipping in the same bottle. Conversely, the tank transfer method (Transvasage method) involves transferring the wine to tanks after fermentation, then rebottling for shipping.
Note The term "complete bottle secondary fermentation method" is used in this article for convenience to distinguish it from the Transvasage method. This is not a commonly used expression, so please note this distinction.
Other Sparkling Wines
There is also a lightly sparkling wine called "Pétillant" that often comes up in discussions.
This is produced by bottling grape juice during alcoholic fermentation (primary fermentation) before fermentation is complete, retaining the carbon dioxide gas produced during primary fermentation in the bottle to create light effervescence. This is called the Méthode Rurale. While this is technically sparkling wine in terms of being effervescent, it is treated as a separate category in this article.
Wines with gas pressure of 3 atmospheres (3 bar) or higher are sometimes classified as sparkling wine, while those below this level are classified as lightly sparkling wine.
For information about the amount of carbon dioxide gas produced during alcoholic fermentation (primary fermentation), please refer to the article "Let's Talk About Fermentation."
Carbon Dioxide Injection: High Volume Production with Great Cost Performance
Production Process
Still wine → Carbon dioxide injection → Bottling → Complete
The simplest method for producing sparkling wine is this carbon dioxide injection method.
This production method simply involves injecting carbon dioxide gas into the base still wine. The key characteristic of this method is that since no secondary fermentation occurs, it can create sparkling wine without altering any of the taste or aroma characteristics of the base still wine.
Since no lees are produced from fermentation, the process called lees removal is also unnecessary.
With simple production processes, easy mass production once equipment is in place, and stable quality—this triple advantage makes it suitable for producing cost-effective sparkling wine. Many sparkling wines in the categories called Secco and Perlwein in Germany are made using this method.
Perhaps because high-pressure sparkling wines can be easily created, many countries and regions regulate the upper limit of bottle pressure relatively low. The upper limit in Germany is 2.5 bar. Since carbonated beverages commonly sold in Japan have about 4 bar of pressure, only lightly sparkling wines can be produced.
Additionally, sparkling wines made using this method must generally indicate on their labels that they are produced using the carbon dioxide injection method.
Charmat Method: Stable Quality
Production Process
Still wine → Add sucrose (saccharose) and yeast → Complete secondary fermentation in tanks → Age on lees for at least 90 days → Lees removal → Flavor adjustment → Bottling → Complete
*Total production period must be at least 6 months from the date of yeast addition
The greatest advantages of the tank secondary fermentation method are the ability to handle large quantities of wine at once and maintain consistent quality control across the entire volume.
Production methods other than carbon dioxide injection require a step of adding yeast to the base still wine to create bubbles. At this time, sucrose, which serves as an energy source for the yeast, is also added simultaneously.
In production methods that create bubbles through secondary fermentation, the taste and aroma will change from the original still wine to varying degrees. The reasons for this are threefold:
- Changes in taste and aroma due to fermentation
- Changes in taste and aroma due to aging
- Changes in alcohol content
The amount of bubbles in the finished sparkling wine is controlled by the amount of sucrose added along with the yeast.
Champagne Production: The Traditional Method
Champagne, beloved by its familiar name "Champagne," is produced using the bottle secondary fermentation method.
Champagne employs the traditional method, which creates the wine entirely within the bottle where secondary fermentation takes place, without removing any wine from that bottle. When people generally refer to the "bottle secondary fermentation method," they are referring to this technique.
Production Process
Still wine → Add sucrose (saccharose) and yeast → Bottling → Complete secondary fermentation in bottle → Age on lees for at least 9 months (*) → Lees removal (Remuage & Dégorgement) → Flavor adjustment (Dosage) → Corking (Bouchage) and mixing (Poignetage) → Complete
*For the Champagne method, lees aging must be at least 12 months, with a total minimum of 15 months from yeast addition
In the bottle secondary fermentation method, the process up to adding saccharose and yeast to the base still wine is the same as the tank secondary fermentation method. However, in this method, the base wine is bottled in commercial bottles from the beginning, and all production processes are consistently completed within that bottle.
It's commonly misunderstood, but during secondary fermentation, bottles are sealed with crown caps rather than corks and stored lying down. The commonly imagined scene of bottles tilted at an angle in special racks relates to the riddling work after fermentation.
After fermentation and the prescribed aging period, the sparkling wine undergoes a process to remove the lees accumulated in the bottle. The work of collecting this sediment at the bottle neck is called riddling (remuage), and the work of freezing the collected sediment and removing it through the pressure release when uncorking is called disgorgement (dégorgement).
Riddling takes 21 days (Germany) to 42 days (Champagne), gradually increasing the bottle angle while rotating 45 to 90 degrees left and right. This slowly collects the sediment at the bottle neck. Following disgorgement, bottles receive an addition called "expedition liqueur (tirage liqueur)"—a liqueur made by dissolving saccharose (usually cane sugar) in wine for flavor adjustment. This is dosage.
Sparkling wine at the completion of secondary fermentation is basically finished as a dry wine with no residual sugar. Dosage aims to adjust the residual sugar of such dry sparkling wine, but sometimes different wines from the base wine are used to add different aromas and flavors.
Bottles with flavor and aroma adjusted through dosage are quickly recorked, undergo a mixing process called poignetage to homogenize the bottle contents, then enter another aging period.
Mechanization Reaches Sparkling Wine Production
The days of dedicating extensive labor and time to riddling are now in the past.
Many people think of sparkling wine production facilities as having bottles inserted into angled boards with holes called pupitres. This scene is rarely seen today. Riddling now typically takes about one week rather than 20 to 40 days.
This dramatic time reduction is achieved using gyropalettes that can process large quantities of bottles 24 hours a day, 7 days a week.
Gyropalettes can hold about 500 bottles per machine. Moreover, using this machinery reportedly causes no quality changes. Therefore, most major producers with high production volumes have now abandoned manual riddling in favor of mechanization with gyropalettes.
Premium Sparkling Wines Use Bottle Secondary Fermentation
Champagne is legally required to be made using bottle secondary fermentation. In Germany, premium special Sekt must also be made using bottle secondary fermentation. While Champagne's legal requirement for specific production methods partly aims to protect tradition, the reason for using bottle secondary fermentation for most sparkling wines lies elsewhere.
The greatest advantage of the traditional method is, to put it bluntly, its marketing advantage.
Being a traditional production method combined with being the method adopted by the globally renowned Champagne creates tremendous influence on consumers. The image of hand-processing each individual bottle in a time-consuming and labor-intensive method also works positively in this case. No one imagines that 500 bottles are being managed simultaneously using gyropalettes.
Naturally, not all sparkling wines made using the traditional method can achieve quality equivalent to Champagne. Moreover, bottle secondary fermentation only indicates the fact that "second fermentation occurred in the bottle"—it doesn't guarantee the quality of the resulting sparkling wine. The equation of bottle secondary fermentation = high quality is simply a misconception.
A Production Method with Notable Individual Variations
The most significant characteristic of this method, for better or worse, is the tendency for variations between individual bottles.
In this production method, all manufacturing processes from secondary fermentation through aging, lees removal, dosage, and shipping are conducted independently for each individual bottle. The various reactions and influences that can occur during any process also occur independently for each bottle. Even the producer cannot completely understand the individual variations of each bottle.
Homogenizing these bottle-to-bottle variations is virtually impossible.
Whether this unavoidable individual variation is viewed as an advantage or disadvantage depends on each producer's philosophy.
Transvasage Method: Eliminating Bottle Variations
Production Process
Still wine → Add sucrose (saccharose) and yeast → Bottling → Complete secondary fermentation in bottle → Age on lees for at least 90 days → Transfer to tanks → Lees removal by filtration → Flavor adjustment → Bottling → Complete
*Total production period must be at least 9 months from yeast addition
The production method that eliminates the unavoidable bottle variations of the traditional method is the "Transvasage method."
The Transvasage method is identical to the traditional method through conducting secondary fermentation and lees aging in bottles. The difference comes afterward: bottles that have completed post-fermentation aging have their contents, including lees, transferred to tanks. After mixing the contents of all bottles, lees removal occurs, followed by rebottling.
The greatest characteristic of this method is eliminating the variations between individual bottles created during secondary fermentation and aging by mixing everything in tanks, thereby achieving uniform quality across all bottles.
Since tanks are typically used for mixing before lees removal, followed by collective filtration, this method eliminates the need for riddling and disgorgement labor and time, as well as bottle storage space. Notably, sparkling wines using this method can still be labeled as "bottle secondary fermentation."
Summary | The Key is Flavor and Aroma Changes Rather Than Just Bubbles
While bubbles are important in sparkling wine, simply creating effervescence only requires injecting carbon dioxide gas.
However, the carbon dioxide injection method is actually restricted through upper pressure limits. This is because bubbles alone are not sufficient.
What truly matters in production methods is the changes in taste and aroma that occur during the bubble-creation process.
The process that most influences taste and aroma changes is the lees aging after secondary fermentation. As you examine each method closely, you'll notice that the differences between methods also represent differences in the magnitude of this influence. Generally, methods that more readily show this influence are considered more valuable methods.
The bottle secondary fermentation method produces more noticeable differences in taste and aroma changes compared to the Charmat method, which ferments and ages large quantities together. Even within bottle secondary fermentation methods, when looking at the final bottles, the traditional method shows more apparent influences from fermentation and aging on taste and aroma compared to the Transvasage method. Almost all "good sparkling wines" adopt the traditional method, while the carbon dioxide injection method—which can create effervescence but produces no changes in taste or aroma—represents the archetypal inexpensive technique.
Separately from production methods, the length of aging time also significantly influences taste and aroma changes. Generally, longer aging periods create greater changes.
For these reasons, sparkling wines that use the traditional method—where changes are more apparent—and particularly those that undergo long aging periods with greater amounts of change, are generally considered superior.
Winemaker intentions come into play when producing sparkling wine. Some want to use traditional methods. Others prefer to minimize the taste and aroma changes that are usually valued. Some want to produce large quantities in short periods. The intentions vary widely. Moreover, creating changes in taste and aroma, or presenting these changes clearly, is not necessarily always beneficial. These different intentions and philosophies lead to differences in the adopted production methods.
Understanding this point while raising your glass of sparkling wine should allow you to enjoy it on a deeper level, appreciating what philosophy it was based on and what aspects the producer focused on during creation.
