Most white table wines and blush wines are bottled a few months after primary fermentation. Heavy-bodied white table wines, such as Chardonnay and Sauvignon Blanc, are usually given several months of bulk aging. Red wines are usually given a year or more of bulk aging before they are bottled.\par
Wine must be brilliantly clear before bottling. Most sound red wines become clear and bright when they are several months old, and clarity is seldom a problem for these wines. On the other hand, practically all white and blush wines require special clarification treatments. These wines generally need fining or filtration before they attain adequate clarity.
Besides being clear, wines must also be stable before bottling. Commercial wineries test to be sure their red wines are cold stable, but most home winemakers do not bother. All white and blush wines should be cold stabilized sometime during the winemaking process, and these wines should be tested for stability before bottling. Wine can be checked for cold stability by placing a small sample in the refrigerator. After 48 hours, the wine sample is removed from the refrigerator and set aside for several hours. When the sample reaches room temperature, the wine is carefully examined for cloudiness or deposits.
White and blush wines can be checked for hot stability simply by holding a wine sample at 120 degrees. After 48 hours at the high temperature, the wine is allowed to stand at room temperature for another 24 hours. Then the wine sample is placed under a strong light and carefully inspected for protein haze or sediment.
Free Sulfur Dioxide
The free sulfur dioxide content of all wines should be measured and raised to about 30 milligrams per liter a few days before bottling. Bottling wine with less than 30 milligrams per liter of free sulfur dioxide will result in a short-lived product.
Wines containing more than 0.2 percent residual sugar are not biologically stable, and these wines can start fermenting anytime. Additional precautions are always required when off-dry or sweet wines are bottled. Commercial wineries use a sterile filtration process when they bottle wines containing residual, but most home winemakers do not have access to sterile filtration equipment. Home winemakers usually add 200 to 300 milligrams of potassium sorbate per liter of wine to prevent fermentation in off-dry or sweet wines. Sorbic acid produced by the potassium sorbate prevents refermentation by acting on the yeast cells, but it does not kill the yeast. Sorbic acid prevents the yeast cells from generating new buds. In other words, sorbic acid prevents yeast cells from reproducing. Sorbic acid does not stop yeast from fermenting sugar, and sometimes wine starts refermenting because the wine contains too many viable yeast cells. The normal dose is about one gram of sorbate for each gallon of wine. One gram per gallon is equivalent to about 2 level teaspoons per 5 gallons of wine.
Some home winemakers turn up the hot water heater a few hours before starting to bottle wine. Then previously washed, bottles are rinsed with very hot water just before filling. Other winemakers rinse each bottle with a sulfur dioxide solution. The sulfur dioxide solution is made by mixing one fourth teaspoon sulfite powder and one fourth teaspoon of citric acid in 750 ml of clean, cold water. This sulfite solution is strong enough to sterilize the bottles, but care must be taken to drain the bottles completely.
Wine is always exposed to a significant amount of air when the bottle is filled, and a bottle filler of some kind should be used to minimize this oxidation. Most home winemakers siphon the wine into the bottles with a piece of clear plastic hose fitted with a plastic wand type bottle filler. Simple bottle fillers have a small valve on the end of a rigid plastic tube. The plastic tube is placed in the empty bottle, and the valve opens when it contacts the bottom of the bottle. Wine begins to flow when the valve opens, and the bottle is filled from the bottom. Little splashing occurs when filling is done slowly, and wine oxidation is held to a minimum. Bottles should be filled until less than 1/4 inch space exists between the top of the wine and the bottom of the cork. Most wand type bottle fillers leave too much air space in the bottle.
Dry corks should be driven into the bottle whenever possible, but many small hand corking machines cannot adequately compress hard, dry corks. Then the winemaker has to soften the corks someway. The normal procedure is to soak hard corks in cold water until they become soft enough to drive with the corker available. A pinch of sulfite can be added to the water to help sterilize the corks as they are soaking. Very wet corks are undesirable, so after soaking, cover the corks with a clean cloth and drained overnight. Corking machines should be adjusted so the top of the cork is set just below the lip of the bottle. Any spilled wine should be removed from the outside surface of the bottles when the corking operation is completed.
All wine should have a label permanently attached to each bottle. Producing custom wine labels with a home computer is easy and fun. If a scanner and a color printer are available, a variety of art work can be incorporated into the label design, and very professional looking labels can be produced easily. Home winemakers often use a "glue stick" apply labels.
Time is required to age wine properly, and no practical way has been found to speed up the wine aging process. Wine ages in two different ways, and each type of aging changes the wine in a different way. Bulk aging takes place when wine is stored in large containers. Bottle aging takes place after the wine is bottled. Red table wines are often bulk aged for a year and then aged in the bottle for a year or more.
Wine must be clear and stable before it is bottled, and home winemakers are always disappointed later when dirty wine is bottled. Wines containing more than 1/4 percent residual sugar can start refermenting anytime, and these wines must be treated in some way to insure bottle stability. Home winemakers often use potassium sorbate to prevent fermentation in off-dry or sweet wines. Wines treated with sorbate should also contain at least 30 milligrams per liter of free sulfur dioxide. Oxidation is the most common fault found in homemade wines, and some wine oxidation always occurs during bottling. A bottle filler of some kind should be used, and the bottles should be filled slowly from the bottom with a minimum of splashing and bubbling. Corks should be set flush or slightly below the lip of the bottle. All bottled wine should have an appropriate label to identify the contents.