Grappa after grappa: reduce, stabilize, filter
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What happens once grappa has been distilled? Let’s find out!
We have often talked about pomace, alembics, and distillation techniques. Arguments, tools, and production processes that concern phases prior to the creation of grappa: the raw material to the actions taken during the distillation itself. But what happens in the distillery once the grappa, percolated through the cooling coils and collected in stainless steel containers, has been obtained?
Generally, grappa produced by hand following artisanal, discontinuous distillation techniques results in a final product that has an alcohol level between 60 and 80%. This is too high to consume pleasurably and is also prohibited by law, which limits that grappa must be between 37.5 and 60% alcohol.
So, the master grappaiolo must begin the fundamental step of reducing the alcoholic grade of the grappa. How do you reduce alcohol?
In practice, a small amount of distilled water is added to cut the alcohol. It is imperative that the water is distilled and demineralized as any introduction of salts or minerals could destabilize the grappa and cause turbidity. There are precise doses of water that must be added in accordance with the Tavola per la riduzione del grado alcoholic, a legislative chart that describes the right percentage of water to add.
It is important to note that water does not, in any way, change the organoleptic characteristics produced through distillation. In fact, it has a net positive impact on the grappa. Thanks to various processes of hydrolysis (chemical reactions to the water), bad-tasting compounds such as miristic acid, lauric acid, stearic acid, oleic acid, linoleic acid, ethyl alcohol esters, methyl alcohol esters, amyl alcohol esters, and acetal alcohol esters are separated and eliminated.
It is also good to note that the final level of alcohol is choice made by the producer; it is important to balance the alcohol with the other aromatic compounds in order not to “burn” them or cover the characteristics of the grappa.
Over time, it is possible for the natural components of the grappa to become insoluble and “manifest” themselves in the liquid. The grappa becomes cloudy and the quality is compromised. To avoid this happening, certain artisanal techniques are used to stabilize the grappa.
By lowering the temperature of the grappa to between -10 and -20° C for at least 48 hours, certain oily volatile compounds raise to the surface of the grappa and can then be mechanically filtered out and eliminated.
This is the last step before bottling or ageing. It reduces all limpidity in the grappa by eliminating all the oils and volatile compounds that cause the grappa to be milky or cloudy looking. Filtration happens mechanically as the grappa is passed through either paper, canvas, pre-formed filter layers or pressure.