Friday, October 31, 2008

Fermentation is Finished. Can I Drink It Yet?

Technically, you now have wine, as the process of converting the sugar in the grapes or must into alcohol has completed.  However, all you have to do is look at it to know you really don’t want to actually drink it just yet.  The wine will be very cloudy, even murky, at this point, with probably some leftover carbonation (CO2) from the fermentation process.  Not very appetizing.

Still, it is good to get to know your wine at every stage of winemaking, starting with smelling and tasting the juice right through putting it into the bottle.  This helps in understanding how each step affects the winemaking process and shows how the juice evolves to become something we all want to drink.

So, back to this murky, fizzy looking stuff we are calling wine.  Once the fermentation is finished, I generally add 50 ppm potassium metabisulfite to the tank and give it some time to settle out, generally a week to 10 days.  This amount of metabisulfite equates to .3202 grams per gallon.  Remember that 28.35 grams equals one ounce.  Metabisulfite is an anti-oxidant that is added in small quantities during the making of a wine.  I begin my additions to new wine at this point so it can have a source of protection right away.   

Now, the source of the cloudiness in the new wine is, of course, mostly the yeast and grape solids that remain suspended.  With time, much of it, if not all, will fall out on its own.  It is not good to wait too long to transfer this new wine off the sediment as the yeast will start to go through autolysis, breaking down and causing bad aromas in the wine, primarily hydrogen sulfide, or the smell of rotten eggs.

After the seven to ten days, rack the new wine off of the sediment, or gross lees(affectionately called muck, a winery technical term), into a cleaned and sterile new tank or other vessel that is the appropriate size for the volume of wine you are racking.  Lees are what the cumulative sediment is called.  In case you are curious, the fact that they are, in fact, pretty gross, is not why they are called gross lees.  The first lees to settle out of the wine are quite large in volume, as much as 50 to 100 gallons in a 1200 gallon tank, and so they are referred to as the gross lees.  The sediment that falls out in future settling is usually called the lesser lees, as they are generally just a few gallons worth.

At this point in the life of the wine, it is very important that the receiving vessel is full at all times.  While the wine was fermenting, it was protected by the fermentation gasses coming off the wine, and, indeed, yeast need oxygen to ferment properly.  Now there is no protection from the oxygen and so it must be eliminated from the receiving vessel.  Oxygen is what causes a wine to brown, oxidize, and eventually (after quite some time) possibly turn it to vinegar.  It will taste terrible, though, long before the vinegar stage.  Imagine an apple that you cut up and leave exposed to the air for awhile.  The surface turns brown, the smell becomes unpleasant, and the apple tastes old before its time.

If there is not one tank that has the correct fit, the next option is to put the wine in multiple smaller tanks or other vessels.  I often fill a tank and then go to a number of smaller vessels.  In our winery you will see, besides various sizes of tanks, 55 gallon drums, 15.5 gallon stainless steel beer kegs, and glass carboys (jugs) ranging from 13 gallon down to ½ gallon.  I don’t waste anything.

Next:  Rack ‘em up!

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