More than a few wine lovers dream of one day having a small vineyard, growing their own grapes, and making their own wine. Producing wine is a lengthy, multi-step process that requires a substantial investment of time even before aging has begun, but if done with care and attention, an amateur wine maker can make some good table wine and call it his own.
Grape Crushing
The first thing to do after harvest is to crush the grapes. These should be rinsed off in cool water first, but the rinsing needs to be gentle to avoid damaging the grapes. Anyone working with a large quantity of grapes should invest in a crushing machine with an automatic de-stemmer, since this will take a great deal of manual labor out of the process. However, many European producers great and small continue to use the old fashioned method of cutting the woody central stem out by hand, putting the grapes in a vat, and crushing them by stomping on them. The juice is then poured into open vats and tested for tartaric acidity, Brix (sweetness), and pH (a different measure of acidity). Brix and tartaric acidity might need to be raised for fermentation, in which case sugar and tartaric acid are added. Adjusting pH requires the addition of sulfites, usually in the form of campden tablets.
Fermenting the Must
After sitting overnight, white grape juice is strained to remove the skins and remaining bits of stem. Red grapes keep this debris. Then the juice, now called a "must," goes to primary fermentation. The addition of the sulfites should have killed any unwanted yeasts and other microorganisms, so now the wine maker adds the specific yeast strain he wants to use. The home wine maker buys these from a supply shop, while many big commercial producers make their own strains of yeast. The yeast starts fermenting the grape juice, converting the sugars into alcohol. This process causes a layer of foam to bubble up to the surface of the vat, requiring each vat to be stirred twice a day to knock down that layer of foam. How long this fermentation goes on depends on the local climate, how high the Brix is, and the intentions of the wine maker. It can last anywhere from 3 days to almost 4 weeks, but for a home wine maker, about a week is normal. The wine can end secondary fermentation as soon as the Brix has dropped by about two-thirds, but sometimes it is desirable to extend things out for a while, particularly with red wines to prolong their contact with the grape skins. To do this, a wine maker will cover the vats with a plastic tarp or lid that has a small vent in it. The fermentation releases carbon dioxide, and by covering the vat, a layer of carbon dioxide forms on top of the must, cutting it off from oxygen and slowing the fermentation process. The must still needs to be stirred twice a day during this prolongation.
Secondary Fermentation
Once primary fermentation is over, secondary fermentation begins. This is transferred to new vats, but in this case the vats are sealed. Home wine makers like to use water carboys for this purpose. These are sealed with airlocks, to permit extra gas released during fermentation to escape without rupturing the container. It should also be noted that many wine cellars are designed so that the area where wine is stored for secondary fermentation is below the workshop where primary fermentation is done. This allows the transfer of wine using only siphon hoses and gravity. The wine will continue to bubble and foam a little for anywhere from 1 to 8 weeks during this period. The must is now what is called "new wine" or "green wine."
Racking and Aging
When all bubbling has stopped, the wine is moved to its aging containers. Once again, it is handy to design the cellar so the wine can be sent down using only gravity and a hose. The transfer of wine is called "racking." The popular image is of a cellar filled with stacked oak barrels, and this is still the standard for fine wine. However, most commercial producers age their table wines in stainless steel vats, and home wine makers like to use used water carboys. What the steel vat and carboy have in common is that both can be have oak chips added to impart that oak flavor, if desired. The aging process can last anywhere from 3 months to 7 months under normal circumstances, but some wines are aged in the barrel for as long as 2 years. During this process, it is necessary to come back every couple of months and rack the wine again because of evaporation, because allowing an air pocket to form in the barrel can cause spoilage. This is usually done by choosing one barrel, and using a siphon hose to transfer wine from it into the other barrels, thereby topping them up. The wine leftover from the topping up barrel can be stored in a smaller container, but it needs to fill that container to avoid the air pocket and spoilage. Any time a racking is done, some sulfites are added to the wine to kill any unwanted microorganisms that have gotten into the wine.
Bottling
After aging, the final step is bottling. A home wine maker will do this using the trusty siphon hose, gravity and a corking press. Commercial producers have bottling machines.
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