Many people still don´t know what is carbonic Maceration. Traditional Carbonic Maceration is a winemaking process that is used almost exclusively in the Rioja Alavesa. It is the way that wine was produced in that area before they learnt how to use the oak barrels from french winemakers at the end of the 19th century. Right now we are experiencing a revival of these traditional Rioja Alavesa wines, even if they have never dissapeared. Nowadays, the Carbonic Maceration denomination (first used by the famous french chemist Louis Pasteur) is synonimous with young, fresh and very fruity wines.
Unlike the carbonic maceration used for the Beaujolais Noveau in France, which is an artifical process, the carbonic maceration used at Rioja Alavesa is a totally natural process that was already used centuries ago for winemaking in the traditional stone “lagars” than we can still find in some small towns. A common feature for both processes is that whole bunches ferment in a carbon dioxide atmosphere, so an intracellular fermentation takes place inside each single grape. The main differerence between both processes is that for the Beaujolais Noveau, this CO2 atmosphere is created artifically inside a closed vat, while in Rioja Alavesa, the CO2 is produced naturally during the fermentation in an open deposit or “lagar”.
You can see the differences between Carbonic Maceration and the usual winemaking process in the image below.
In the traditional Rioja Alavesa Carbonic Maceration, instead of removing the grapes from stems, whole grape clusters are gently tossed into the deposit and it is only the weight of the clusters above which crushes the grapes below. This way, fermentation starts spontaneously in the wine mash produced at the bottom of the deposit and CO2 is released. The CO2 displaces the oxygen inside the deposit and the carbonic maceration process starts. As there is no oxygen, the yeasts will change from an aerobic respiration to an anaerobic one, and the grapes that are not submerged into the wine mash will start an intercellular and enzimatic fermentation.
Due to the high accumulation of CO2, the grapes will burst and the wine must will be released. The solid mass will fal down and the fermentation foam caused by the yeasts will appear in the surface and the edges of the deposit.
Once out of the deposit, the wine that has been obtained will perform the malolactic fermentation in another deposit. Later on the wine will be clarified and eventually filtrated (not very common in high quality wines nowadays), and finally bottled.
The process we have descrived above will last aproximatedly between one week and ten days, depending basically on the temperature that is obtained, which usually is around 30- 32 ºC.
Main Characteristics Of Wines Obtained By Carbonic Maceration
Generally speaking, wines obtained by carbonic maceration must be consumed within the next year of the harvest, even if we can always find some exceptions which can age very well.
They are wines with dark red colour and a purple edge. They have a fragant nose with blueberries and violet aromas. An explosion of fresh fruit in mouth, expressive and juicy, which makes them very attractive for people who are not used to drink wine.
The main defects we can find in these type of wines are the low acidity and sometimes the excessive carbonic concentration.