Carbonic Maceration

The inherent charm of French Beaujolais doesn't come about by traditional fermentation which converts sugars to alcohol using yeasts.  Carbonic maceration is how the winemakers in Beaujolais (and elsewhere) do it.  This fermentation process uses an anaerobic tank of carbon dioxide to initiate fermentation using the enzymes of whole, not crushed, grapes as a catalyst.  The release of the enzymes in such an environment breaks down the grape sugars into alcohol without introducing yeasts from somewhere else.  CO2, being heavier than oxygen, permeates fruit skins forcing oxygen out while breaking down sugars and malic acid to produce alcohol.  This is intracellular fermentation.

Does wine made using this process taste different from wine traditionally fermented?  While Beaujolais and other whole grape fermented wines still show the polyphenols (antioxidants), color, flavors and tannins in traditionally fermented wines, they are lighter, fresher and fruitier and lower in tannins than traditionally made wines.  It's a wine style very much in keeping with modern tastes.

Our preceding post was about the ten best vineyards in Beaujolais.  Each region has their own winemaking methods.  The more southern regions have the benefit of a longer growing season and the region's Mediterranean climate.  Carbonic maceration makes sense there.  The northern parts want a more Burgundian product so they typically finish their fermentation the traditional way to get a bigger wine.

Carbonic maceration is as old as grapes, themselves, by the way.  Whenever fruit is held in a container, even a slatted wooden crate, the weight of the fruit at the top crushes to some extent those at the bottom releasing carbon dioxide facilitated by ambient yeasts.  The heavier CO2 forces the O2 away creating a carbon dioxide-heavy environment.  The whole fruits higher up in the container will then naturally start to ferment.