Syrah In My Closet ( Update )
Written By: Michael Keba on Thu, Jan 17th 2008
The grape juice in my closet is officially wine. Actually, it has been wine for a couple months now. To test the progression of fermentation, winemakers use an instrument called a hydrometer. A hydrometer tests the specific gravity of a liquid, which is the density of the liquid compared to the density of water. Sugar has a higher density than water, so the specific gravity of grape must (raw, unfermented grape pulp) can be used to determine the percent sugar it contains. Yeast converts sugar to alcohol in the process of alcoholic fermentation, the most important chemical reaction in wine:
C6H12O6 (glucose) => 2 C2H5OH (ethanol) + 2 CO2 (carbon dioxide)
Ethanol has a lower density than pure water, so as the sugars in the must are fermented, the specific gravity of the liquid drops. A completely dry wine has no residual sugar, whereas a sweet wine has not completely finished fermentation. At this point, the winemaker has calculated the desired specific gravity for the wine, and makes sure that his precious potion reaches this number.
The proof of the finished wine can be projected before the grapes are even crushed. The harvest begins when the grapes reach a certain degree Brix specified by the winemaker (or whoever controls of the vineyard). One degree Brix is equal to one percent sugar by weight. The final alcohol concentration is roughly estimated by multiplying this number by a factor of 0.55. The owner of the vineyard where sourced my syrah quoted the grapes to be at about 25 degrees Brix. Knowing this, I am projecting the alcohol concentration in my finished wine to be about 13.75.
If you recall from my earlier blogs (Crush at Home and Syrah in my Closet), I have almost no winemaking equipment. Because I have no hydrometer, I had no way to monitor the progression of the fermentation other than the rate the carbon dioxide bubbled to the surface of the vat. In the beginning, it bubbles surprisingly fact. It looks like it is alive (well, technically it is). I believe it took a week to complete most of the fermentation.
During fermentation, a winemaker takes part in the joyous tradition of "punching down the cap." A red wine is fermented with all of its seeds and skins left in the slurry, which forms a solid mass as floats to the surface of the liquid wine. The longer the wine is left in contact with its solids, the more color and tannins that are extracted. The cap is usually punched down at least twice every day. Also, one must be wary of the fact that a whole lot of heat is given off during fermentation. If the temperature gets too high, the yeast will begin to die off. One must carefully monitor the temperature to avoid any problems. Most red wine is fermented between 70 degrees – 90 degrees F and most white wine at 55 degrees – 70 degrees F.
ATTENTION PROSPECTIVE WINEMAKERS:
Your fermenting masterpiece WILL give off a pungent odor. While it may be attractive to you, it might not impress the people that you live with. If you are forced to utilize a spare closet like I have, be prepared to bribe them on a constant basis. Most importantly, like any parent, you must not neglect your infant wine. Doing so will result in an obnoxious stench of rotten eggs that will permeate through all of your living quarters. Be warned.
Let's just say that I hit a few bumps along the way. It was fun though. I learned a lot. My roommates will get over it and have something to brag about when their drinking my wine in 10 years. Next time I'll tell you about how I acquired a nice big press from the student wine organization and continued the journey.
