Wednesday, October 7, 2009

Fermentation, Remontage, Delestage, and Babo

  So fermentation is well under way and we are working hard in the cantina to "dompter la fermentation" as PJ says. We can "dompter" (tame) the fermentation by measuring and changing the temperature of the wine. Of course there are chemicals that one can buy to start fermentation, to slow fermentation, to extract more color, to extract more tannin, to soften the tannins, to start Malolactic fermentation and on and on and on. This week when we were at the EnoAgricola (vineyard equipment shop), to pick up tubing, we saw people buying massive amounts of these chemicals. But one of the wonderful things about wine is that it is a natural process and requires no additives. If one is vigilant and dedicated, fermentation can be tamed, or least kept from going crazy by regulating the temperature of the fermenting liquid. Natural wine is made without adding viticultural yeast strains (or anything else for that matter). The skins of the grapes themsleves are a perfect environ for many different local yeasts and enzymes which are activated when they are exposed to the high level of sugar in the fresh grape juice. The juice starts its life as a mixture of whole uncrushed grapes, partially crushed grapes, skins, pips (seeds) and juice. In Italy we uses Babo as our measure of sugar content and it is expressed numerically. In the US we use Brix, expressed in degrees. The 2009 Casa Raia Brunello (there are three, 30 hectoliter vats)  began its life at 21 Babo (around 25 Brix) and 23 degrees Centigrade. Both the temperature and the Babo are measured by a floating hydrometer. As fermentation begins the yeasts and enzymes start to eat the sugars in the juice, expel carbon dioxide, and heat the mixture up. One can tell where the baby wine is in its life cycle by these two simple measurements. There are a lot of solids in the wine at this stage, and these solids rise to the top of the liquid in a large, hot, floating mass called the cap, pictured below. 
Three times a day we take the temperature of the wine and the sugar level and take the appropriate action. Because fermentation stops between 36 and 38 degrees Centigrade it is important for the winemaker to test the wine regularly. This means, for the first rapid part of fermentation, we could be in the cellar until 1 or 2 am doing one of two things to help regulate temperature. The first thing is called Remontage.

 Remontage is done at least three times a day for each vat of fermenting wine. It involves cycling wine from the bottom of the vat back over the top of the cap. This process does two things: first it helps to aerate the wine and second it evens out the temperature of the entire vat. The wine below the cap is slightly cooler  and most of the yeasts and enzymes are living, eating and producing alcohol in the cap, and it is important to keep it wet with fresh sugar for the little guys to consume. The second technique the natural winemaker employs for controlling temperature is called Delestage. Delestage, also called racking off, is when the winemaker removes the liquid from the fermenting vat and moves it to another container in order to cool the wine back to a safe level. Delestage at Casa Raia is done by circulating cold water into two flat, stainless steel containers, submerged in the wine. This involves more work, more cleaning and slows fermentation so it is done more or less at the last possible moment, when the wine is around 34 or 35 degrees. 

Winemaking involves intuition, certainly knowledge and skill, especially when one is not using chemicals to control the process. If the wine gets too hot, or too cold, fermentation stops and you have too much sugar and dead yeast. Big problem. Fermentation, once it begins, can go at any speed. One vat of Brunello from the same vineyards, picked the same day as the others might ferment much more slowly than the others. One might take days to start, while another only hours, and this has nothing to do with the quality of the final wine, and is part of the natural process. The winemaker must be patient and listen to the wine and help it along the way with as little interference as possible. This means long hours in the cantina, and lots of work, but it has a satisfaction that is absent when winemaking is reduced to measuring out chemicals and dumping them into "wine". 
When you open the door to a vat of naturally fermenting wine you feel the heat, the smell of fermentation and you know that it is alive and there is something indescribably amazing and beautiful about that. Man has been taming these tiny wild yeast beasts since agriculture was invented, and it fills you with a wonderful feeling of connection to history and your fellow humans. Or maybe its just the CO2 messing with your head.....

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