Carbonic Maceration of Wine Grapes

Carbonic Maceration of Wine Grapes

Carbonic maceration is a unique method of fermenting grapes into wine. While it doesn’t completely ferment all of the sugar into alcohol, it does impart a unique character on the wine. What makes this method of fermentation so different is that you begin with whole, unbroken grape clusters still on the stems. The grapes are then placed in a sealed fermentation container filled with carbon dioxide. The carbon dioxide discourages yeast fermentation and encourages enzymes naturally present in the grape to be released. Once released the enzymes break down the sugars into alcohol. Thus the sugars are fermented without the help of any micro-organisms. What Types of Wine Are Made from Carbonic Maceration? The most notable wine produced using this method is Beaujolais Nouveau which is made from Gamay grapes. Characterized by its fruity flavors and lack of tannins, this red wine is meant to be consumed the same year the grapes are harvested. The entire process from harvest to bottling takes between six and eight weeks. Traditionally Beaujolais Nouveau is available by the end of November in America. It has become somewhat of a tradition among winos to drink Beaujolais Nouveau at Thanksgiving. Many believe that the quality of this wine in a given year is an early indicator of the quality of the entire vintage. Other wine makers and tasters alike believe this to be a bit of a stretch. Admittedly it is hard to imagine drawing any conclusions about an entire vintage based on a single style of wine that was cranked out in a matter of weeks. The Carbonic Maceration Process To pull this off successfully you’re going to need to be very careful while handling your grapes to ensure that no grapes are broken open, this is critical. Take the unbroken fruit and place it in a seal-able fermentation container filled with carbon dioxide. This is done to prevent oxidation and to inhibit spoilage micro-organisms from taking hold. With the grape clusters placed gently in the carbon dioxide flushed container seal the lid, place your airlock, and start monitoring the temperature. It takes approximately five to fifteen days for carbonic maceration to complete. During this time only about 3% alcohol by volume is produced. Thus you’ll need to follow this fermentation a yeast fermentation. A lot of heat is generated during carbonic maceration. Make sure that the grapes don’t get too warm otherwise it may take on cooked flavors. Generally speaking keeping your temperature below 90° F / 32° C will prevent this. After carbonic maceration has finished open the fermentation vessel and then crush and press your grapes to release the remaining sugars and the alcohol produced thus far. Once extracted the remaining juice should be stabilized and inoculated with your yeast of choice. Traditionally a wine made this way would not spend any more time on the skins. Sufficient color, flavor, and aroma extraction is achieved during carbonic maceration thus an extended maceration is not needed. It is also important to limit tannin extraction so that the wine may be consumed sooner. More tannic wines need more aging to become palatable. Amateur wine makers could use a plastic fermentation...

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Maceration of Wine Must

Maceration of Wine Must

Maceration Basics Simply put maceration is the process of soaking crushed grapes, seeds, and stems in a wine must to extract color and aroma compounds as well as tannins. This is where red wines get their color and tannins and it is the lack of maceration that makes white wines so light in color and nearly tannin free. There are actually several different types of maceration processes. The three most common are the extended maceration, cold soak, and carbonic maceration. Carbonic maceration is a bit different than the other two and will be discussed only briefly. Maceration may take place either before or during fermentation. A cold soak takes place prior to yeast fermentation while an extended maceration takes place during primary fermentation at least but may be allowed to continue throughout the entire fermentation. The process begins as soon as the grapes skins have been ruptured. At this time the juice is released from inside the grape and comes in contact with the exterior of the grape skins as well as the stems. To end maceration simply remove the skins, seeds, and stems from your must. It should be noted that not all grape varietals benefit from maceration. Generally speaking Bordeaux style varietals including Cabernet Sauvignon, Merlot, Cabernet Franc, and Petit Verdot can benefit from this process while other varietals may be too delicate and can become over extracted. The following are some important things to monitor while carrying out this process on your own wine musts. Tannins The main sources of tannins in wine are grape skins, seeds, stems, and oak. Given that three of the four major sources of tannins are present during maceration monitoring tannin extraction is very important. You do have some control over how much tannins are extracted by manipulating maceration temperature, duration, and the amount of stems included. By reducing any of these three variables you can reduce the amount of tannins extracted. If you over extract the tannins you can try to fine them out but you may end up having to age the wine much longer than you originally attended. Over time those tannins will bind together and precipitate out, however you may be waiting several years if this is taken too far. Temperature Management When maceration takes place during fermentation temperature management becomes a critical part of the wine making process. The yeast produce carbon dioxide during fermentation which makes the skins, seeds, and stems float to the top forming the “cap”. In a fairly short amount of time the cap becomes quite thick and will insulate the fermenting must below. Fermentation is an exothermic process which means that the process itself gives off heat. The cap traps that heat and can cause your must to get too hot and take on cooked flavors. To release the heat you must punch down the cap forcing the solids back down into the must. This helps heat escape but also puts the solids back in contact with the must to increase color, aroma, and tannin extraction. Possible Faults The two things that most often go wrong during an extended maceration are the...

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