Tuesday, 19 November 2013

A different way to encourage extraction

When red wine is fermented, the grape skins (or pomice) goes into the fermentation vessel and some form of agitation is used to encourage the interesting substances in the skins to leach out into the fermenting must to end up in the finished wine. The most dramatic of these is used in the brief fermentation of that great fortified wine, port, in which the maceration and fermentation is cut short by the addition of alcohol. The classical way to aid maceration is foot treading, but robot treading and pumping over also number amongst the methods employed. The latter is also used for ordinary still reds, as the the simple expedient of manually pushing the cap down into the must.

I learnt of a very different way involving pressure vessels as I was finding out (as well as tasting) a German Fruhburgunder. First I though it is the same as the ordinary Pinot Noir which in German is Spatburgunder, but in fact they count as two different varieties. The grapes ferment in a pressurized vessel in which the pressure is released when the pressure reaches three atmosphere above ambient. Imagine shaking a bottle of soda pop and then unscrewing the cap. Everything bubbles vigorously and the contents are thoroughly churned. That would also happen to the must as well as the skins, thus aiding extraction of the interesting material from the latter. Well one lives and learns!

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