Carbon maceration The secret of "vin nouveau" At the end of November the French tricolour is everywhere - 'Le Beaujolais nouveau est arrivé.', say the advertisements. The fashion for new young wine is one which has also affected Italian producers in recent years. But how is it that a wine is ready only a few weeks after the grapes have been picked? The secret is called carbonic maceration, also known as aromatic fermentation because it produces a wine which is known for its bouquet. It involves filling a container with intact grapes and sealing it hermetically for 7-20 days at a temperature of around 30°C, saturated with carbon dioxide. A few of the grapes, those nearest the bottom, are squashed by the weight of the grapes above and release must which starts to ferment, producing alcohol and carbon dioxide. This gas (which can also be introduced on purpose) rapidly saturates the environment, which causes the intact grape cells to change their metabolism (it should not be forgotten that the cells in the grape skins are alive) producing a type of intracellular fermentation (or autofermentation). Because of this suffocating environment in particular the permeability of the skins changes, so they lend the pulp their various constituents more easily, especially the colorants. In other terms, maceration occurs even though the grape is still whole. At the end of this period in the tank full of carbon dioxide the grape contains far less acids than before and the malic acid in particular has been consumed. New odorant compounds are also formed - they smell of strawberry and raspberry as well as having an intense grape smell. At this point the grapes are pressed and placed in the fermentation tank where, after two or three days, the sugars will all have been transformed into alcohol. The wine obtained matures quickly, so much so that it must be bottled by the end of December and consumed not long afterwards.