The subject of winemaking is perhaps unmatched in the number of methods, opinions and preferences....but here's what I do. Bear in mind that this is a red wine method.
Harvest Day
It is preferred that the fruit be harvested by unpaid labor. Friends and family. You know who you are.
We pick early in the morning, offering a breakfast table to those who haul five gallon buckets of fruit from the vineyard to the crusher/destemmer. I perch mine above a tarped area of the garage, with sanitized food-grade Brute trash cans below. The crusher gently bursts the skin of the grape to expose the juice without breaking any seeds. The stems are removed, since they contain tannins which may be objectionable, or green, in the wine.
Pre-Fermentation
Once the crushed grapes (now called "must") are located in the Brutes, we measure and document the pH, total acidity (TA) and Brix of each container. In our warm climate, the pH is usually too high by the time the fruit is ripe. So we add tartaric acid to correct the acidity and pH. Brix can be reduced with water addition, or increased with sugar addition, neither of which I've done so far, or really expect to since I control the vineyard.
We also add a light dose of potassium metabisulfite, which is strong enough to keep wild yeasts from multiplying, but gentle enough to allow fermentation by our cultured yeasts with superior characteristics. We also add a dose of enzyme to enhance fruit breakdown and color extraction.
The
skins contain both color and tannins that to some degree add to the
perception of the wine. The longer the juice is exposed to the
skins, the more color and tannin can be extracted. But it is
thought that once the wine contains a higher level of alcohol, harsher
tannins can be extracted, requiring years of aging before soft
enough to enjoy. So in order to get long skin contact time
without alcoholic tannin extraction, we hold off the start of
fermentation using a method called "cold soaking". Pellets of dry
ice are delivered on harvest day and are added to the top of the must,
cooling below fermentation temperatures. The Brutes are sealed up
for sanitation and allowed to sit for three or four days in the cool
cave, developing rich red colors in the must.Inoculation
The Brutes are then carted back to the tarped floor of the warm garage for fermentation. The must is checked again for pH, TA and Brix, documented and adjusted, if necessary. A nitrogen nutrient is added to the must to assure a healthy environment for the yeast propagation. Once the must is warm, the cultured yeast is "started" in warm water and poured gently across the top of the must. Within hours, foamy yeast colonies are visible, and once violent, mixed into the entire Brute container with a stainless steel plunger.
Fermentation
The coolest part of winemaking!! As the yeast converts sugar to alcohol, it releases carbon dioxide. The gas bubbles rise, along with the lighter grape skins to form a "cap" of relatively dry skins about nine inches thick. Since we want lots of contact between the new wine and the skins, the cap is pushed back into the wine as often as possible, perhaps six or eight times a day during the very active early days of the ferment. The first plunge results in a foamy, purple volcano that should be managed carefully to avoid purple clothing. It's really quite exciting.
Fermentation also generates heat. The temperature is monitored and allowed up to 90 degrees at it's peak, but only for a day and then cooled if necessary.
Once things settle down, at perhaps a Brix of 10, the cap is scooped into a clean Brute, and the wine ladled off of the seeds sitting at the bottom, which are then discarded. This method, called "Delestage" will help reduce any green tannins attributable to the seeds. Additional yeast nutrients are added in hopes of non-stop fermentation of all sugars.
Pressing
Remember the concept of minimizing alcoholic extraction of tannins? Pressing at a Brix of 1 or 2 will limit this extraction, allowing for earlier enjoyment of the wine. Some prefer to leave the wine on the skins longer, adding structure to the wine, but requiring perhaps additional aging in the cellar. This concept is called "extended maceration". With an empty cellar, my first vintage was pressed early, at a Brix of 1. I'll consider more structure once I have something to enjoy.
The cap is scooped into a separate Brute and the new wine is ladled into the press basket. As the wine runs freely out of the press basket, it is strained through a stainless steel kitchen strainer to catch the occasional seed or skin and then collected into a 5 gallon bucket, and then dumped into another clean Brute. Most of the wine simply runs through this step without pressing of the skins trapped in the bucket or strainer. This wine is termed "free run" and is considered premium, low in harsh tannins and usually labeled as "reserve" or "not for the in-laws".
Eventually the skins will build up in the wooden press bucket. The press is then operated to squeeze the "press wine" from the skins. It is kept separate and labeled "in-laws". Press wine can also be added to free run for a desired level of structure. The caps (removed earlier) are then loaded into the press basket and pressed. The amount of wine in the cap can be quite surprising.
The wine is then settled for a day or two to confirm complete fermentation, and then settling of the dead yeast cells, or "lees". The wine is then pulled off the settled lees and loaded into oak barrels.
Malolactic Fermentation (MLF)
Big word, huh? One of the objectionably tart acids in the new wine is Malic acid. It can be converted to a softer Lactic acid with the addition of a cultured Malo-Lactic bacteria. While done selectively in white wines, almost all red wines undergo MLF. The bacteria culture is added to the barrels with another nutrient to promote a healthy inoculation at a temperature of 70 degrees. This fermentation can be confirmed by a "rice krispie" sound, and completion is confirmed by a complex chemical analysis called chromatography.
Barrel Aging
Once MLF is complete, sulfite levels are increased and temperatures are lowered to limit oxidation of the wine. Additionally, the barrels are "topped up" with either bottled wine, or wine set aside in carboys that didn't fill a full barrel.
Wine continuously evaporates through the wood of the barrel staves, and as the level drops, a vacuum occurs which slowly pulls air through the wood, providing a beneficial "micro-oxygenation" that assists in the aging of the wine. Still, every two to three months, the wine is racked off of any settlement in the barrels, the barrels cleaned and the wine replaced.
With time, the wine runs clear, the tannins smooth and a gentle vanilla oak flavor is imparted to the wine. The wine is tasted frequently to assure too much oak is not added, which may or may not be corrected with additional aging in the bottle. Next is bottling, corking, labels and time....
Big Finish
The above is by no means complete. There is also a lot of hemming and hawing. I'm also certain that any winemaker will disagree with at least something in here. Yet, that is what makes each wine unique. Making each decision and taking each step is challenging and exciting. And therefore rewarding.
Some Great Links
A free online winemaking manual from a local hero: http://www.geocities.com/lumeisenman/
Another manual: http://morewinemaking.com/search/102638
A great fermantation manual from Scott Laboratories: http://www.scottlab.com/products/fermentation/documents/ScottLabs_woprices_rv.pdf
The best book I've read on wine:
http://www.amazon.com/Home-Winemaking-Step-Step-Iverson/dp/096579363X/ref=sr_1_2?ie=UTF8&s=books&qid=1199152032&sr=8-2
A forum where I learned almost everything I know about wine (thanks Joel): http://www.winepress.us/forums/index.php