The grape picking season – the vendemmia which started last month (article here) on most of the vineyards around Barga is now over for 2010. The svinata – moving the crushed grapes after they had started the first fermentation, from the wooden barrels to the glass demijohn took place earlier on this week. The grapes have almost finished their story in the winemaking process either being thrown away or used as fertiliser – but not always, as in some cantinas they will be used as the prime ingredient for grappa making. This time it is not fermentation that is the key to the alcohol making process but distillation.
The crushed grapes are boiled in a sealed container, usually copper and the vapour given off is passed through a thin copper pipe that is cooled in running water.
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The thin trickle of clear liquid that comes out at the other end is grappa which can be 50 -70 % proof depending on the quality of the grapes or the experience of the grappa maker.
The crushed grapes are heated until it gives off steam, which is then captured, cooled, and condensed into a liquid. The highly volatile substances such as methyl alcohol, ethyl esters of acetic acid, and acetaldehyde have the lowest boiling point, and since they not only ruin the taste of the distillate but are in some cases poisonous, they are cut off from the run as the so-called head. The purest alcohol and aromatic substances appear as steam at medium temperatures. Only this middle part of the run, the “heart” of the distillation, is condensed into grappa. In the “tail,” which is also cut off, are water and still more impurities, chiefly fusel oils such as amyl alcohol. The distiller has to be able to distinguish between the several phases and be certain of capturing only the middle run. The more successfully it is separated from the head & tail, the purer and more delicate the distillate
A couple of short videos showing another Grappa making process close to Barga filmed in 2006 which have since been seen over 75,000 times on youtube.