Copyright 1999
Chapter 17
BOTTLING
Light, white table wines and most blush wines are bottled a few months after primary fermentation. These wines are valued for their young fruity characteristics, and they do not benefit from aging, and light. Heavier-bodied white table wines, such as Chardonnay and Sauvignon Blanc, are usually given several months of bulk aging. These heavier white wines and light, fruity red wines are usually consumed when one or more years old. Heavier style red wines are usually given one to three years of bulk aging before they are bottled, and then the highest quality red wines are often several years old before they are consumed.
PRE BOTTLING ADJUSTMENTS
Bottling is the culmination of the entire winemaking process. Wine is always oxidized to some extent when the bottles are filled, and experienced winemakers take special care throughout the bottling operation. Oxidation reduces table wine quality, so excessive foaming and splashing should be avoided whenever possible.
Although bottling may seem like a simple procedure, several important issues need to be considered before the bottles can be filled.
Clarity
All wines must be brilliantly clear before bottling. Most sound red wines are 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 and most rose wines require special clarification treatments. These wines generally need fining and tight filtration before they attain adequate clarity.
Stability
Besides being clear, wines must also be stable before bottling. Blending should be done well before bottling time, and the winemaker should observe the new blend for several weeks to be sure the new blend is stable. 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, and these wines may require an additional cold stabilization treatment if much tartaric acid is added late in the winemaking process. Sometimes a white or blush wine needs a small acid addition just before bottling to improve acid balance. Citric acid is often used for this purpose, and additional cold stabilization is often not needed when moderate amounts of citric acid are used.
All white and blush 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 by holding a wine sample at 120 degrees. After 48 hours at the high temperature, the wine is allowed to stand over night at room temperature. Then the wine sample is 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.
Residual Sugar
Wines containing more than 0.2 percent residual sugar are not biologically stable, and these wines can start fermenting anytime. Most wines are a complete loss when fermentation restarts after the wine is bottled. To avoid such catastrophic losses, additional precautions are always required when off-dry or sweet wines are bottled. Generally, four methods can be used to deal with the residual sugar problem. (1) The wine can be pasteurized to kill the yeast. (2) Ethanol can be added to raise the alcohol content of the wine above 18%. (3) Sterile filtration can be used to remove all of the yeast cells when the wine is bottled. (4) A special material can be added to prevent yeast in the wine from fermenting the residual sugar.
Pasteurization reduces wine quality, so this process is seldom used for quality table wines. Adding ethanol is suitable for dessert wines, but additional alcohol is seldom desirable in table wines. Commercial wineries use a sterile filtration process when wines containing residual sugar are bottled, but most home winemakers do not have access to sterile filtration equipment. Home winemakers usually add potassium sorbate to prevent fermentation in off-dry or sweet wines.
Potassium Sorbate
Potassium sorbate does not interact with the residual sugar in any way. Sorbate prevents fermentation by acting on the yeast cells, but it does not kill the yeast. Sorbic acid passes through the cell membrane easily, and the yeast cell is prevented from generating a new bud when enough sorbic acid molecules have accumulated. In other words, sorbic acid prevents yeast cells from reproducing, but it does not stop yeast from fermenting sugar.
Sometimes potassium sorbate does not prevent fermentation from restarting because the wine contains too many viable yeast cells. When potassium sorbate and sugar are added to a wine containing many viable yeast cells, the sorbate prevents the yeast from reproducing, but enough yeast cells may be present all ready to ferment the additional sugar. Then, fermentation often occurs after the wine is bottled. The wine is spoiled, and the winemaker is unhappy.
A different situation exists when sorbate and sugar are added to a well-clarified wine. The clean wine contains very few yeast cells. The sorbic acid prevents the small number of existing yeast cells from reproducing, and the added sugar is unaffected. Even if fermentation occurred, only a tiny amount of the added sugar would be lost because only a few yeast cells are present in the wine. In time, the few active yeast cells in the wine grow old and gradually die. After a few months, the wine contains practically all of the added sugar and very few viable yeast cells.
Using just the right amount of sorbate can be a problem. Wine flavor can be adversely affected when too much sorbate is used, but the wine may restart fermentation if too little sorbate is added. The sorbate needed to keep yeast cells from reproducing depends upon several wine properties. 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. Wines with a high alcohol content, low pH and 30 to 50 milligrams per liter of free sulfur dioxide present require less potassium sorbate.
An additional problem sometimes develops when potassium sorbate is added to wines low in sulfur dioxide. Large bacterial populations can exist in wines low in sulfur dioxide. Sometimes the bacteria in the wine can react with the sorbic acid, and a strange geranium-like odor is produced.
Large quantities of potassium sorbate were used by commercial wineries to stabilize their off-dry wines before practical sterile filtration equipment became available. However, sorbic acid is not widely used today because of the potential flavor problems and the high cost of potassium sorbate. Now, sterile filtration is the preferred treatment, and few commercial wineries use potassium sorbate.
Potassium sorbate is not a very stable material. Unopened containers have a reasonable shelf life, but after the package is opened, potassium sorbate can deteriorate rapidly.
FILLING BOTTLES
New glass bottles leave the factory in a sterile condition. However, new bottles often contain carton dust, and even new glass should be rinsed. Bottles stored for extended times should always be rinsed before filling. Some home winemakers turn up the hot water heater a few hours before starting to bottle wine. Then clean (previously washed), used 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 1/4 tsp. of sulfite powder and 1/2 tsp. 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.
Plastic milk crates are a convenient way of handling glass while bottling. Milk crates hold about 20 bottles, and they are easy to keep clean. If one end of the crate rests on a block of wood, the empty bottles will be held on a slant, and the angle makes filling easier.
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 when bottling to reduce this oxidation. Most home winemakers syphon the wine into the bottles with a piece of clear plastic hose fitted with a plastic wand type bottle filler. A simple bottle filler has 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.
Small, two or three-spout gravity type bottle fillers specifically designed for home winemakers can be purchased for about one hundred dollars, and these fillers are very convenient moderate quantities of wine are made. Gravity fillers are much faster than wand type fillers, and smaller commercial wineries often use larger, multiple spout gravity fillers. A gravity filler consists of a small tank to hold the wine, a float valve assembly that keeps the wine in the tank at a constant level and filler spouts. Tanks on small, two and three-spout machines can be filled by siphoning with large diameter tubing. Tanks on machines employing several spouts must be filled with a small transfer pump.
Operation of gravity type bottle fillers is quite simple. The operator places an empty bottle on an empty spout, and the machine starts filling the new bottle. Filling continues unattended while the operator removes other full bottles and places empty bottles on the spouts. When the new bottles become full, the machine automatically stops filling. Once the filler is adjusted properly, all of the bottles will be filled to the same uniform level. Little spillage occurs, and if the operator is careful, the outside surfaces of the bottles remain clean and dry.
Although these little machines are simple in design, they are surprisingly fast. Most gravity bottle fillers can fill two bottles per minute for each spout. For example, a machine with four spouts can fill more than eight bottles a minute, and one person is kept quite busy changing the bottles.
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. Some winemakers prefer to fill and cork one bottle at a time. Other winemakers prefer to fill several bottles and then cork the lot. In any event, leaving full bottles of wine open for long periods is not a good practice.
Corking
Standard wine corks are sold in large, sealed polyethylene bags containing one-thousand corks. The corks are sterilized with sulfur dioxide gas when packaged, and the corks remain in a sterile condition until the bag is opened. The water content of the corks is carefully adjusted just before packaging, and the humidity in the bags is carefully controlled. Corks taken from a sealed bag are soft, pliable and resilient. They can be driven easily, and the soft, pliable corks quickly conform to the neck of the bottle and form a tight seal.
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 little recourse, and softening the corks is necessary. 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 because excessive "cork water" will be left when the corks are driven into the bottle. Cork water can be avoided by soaking the corks for a few hours, and then the corks are covered with a clean cloth and drained overnight.
Corks can be quickly softened (and probably sterilized) in a microwave oven. However, corks burn easily, so some practice may be needed. First the corks are rinsed in clean water and then sealed a plastic, zip-lock storage bag. The sealed bag is then placed in a microwave oven. Some experimentation with the time and power settings will probably be necessary.
Corking machines should be adjusted so the top of the cork is set just below the lip of the bottle. Spilled wine should be removed from the outside surface of the bottles when the corking operation is completed because wine left on the glass makes labels difficult to apply. In addition, mold often grows on the spilled wine, and after a few weeks an unsightly residue can form on the bottle.
Labels
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.
Some glues wrinkle light weight papers, so labels are best printed on medium weight paper. Some bond papers seem to work well. Papers can be tested by wetting one side of a sheet with water, and then carefully observing the paper for a few minutes. Papers that stretch and wrinkle excessively will probably will not be suitable for labels.
Layout 4, 6 or 8 labels on standard 8.5 X 11 inch paper. If the layout is carefully done, the labels will be easy to cut with a paper cutter, and little paper will be wasted. A few extra labels should be made when the labels are printed. The extra labels can be pasted on the cartons to identify the contents, and the labels give "case goods" a professional look.
Capsules and labels can be applied when the bottles are clean and dry. Home winemakers often use an inexpensive, short bristled, 1 « inch brush to apply glue to labels. White "Elmers" glue works well with heavy weight papers. Unfortunately, this glue is water-based, and it may shrink or wrinkle some types of papers.
Cut a piece of cardboard a little smaller than the label. Place the label face down on the cardboard and apply the glue with the brush. Apply the glued label to the bottle and quickly smooth out any wrinkles. Try to place the label in the proper position the first time to avoid smearing the bottle with wet glue. Clean the brush and glue container with warm soapy water when finished. A "glue stick" is very convenient when just a few bottles are being labeled. When labeling "short runs," commercial wineries use a "label paster"to apply just the right amount of glue to the back surface of plain paper labels. These machines apply glue quickly and easily, and they save a great deal of time. Unfortunately, small pasting machines are expensive. New machines cost $600 or $700. Second hand machines are in great demand, and they are very hard to find.
Capsules
Most home winemakers and many commercial wineries use plastic capsules. Plastic capsules can be obtained in a variety of colors, and they can be custom printed. Plastic capsules are inexpensive, and they provide an attractive, finished look to any bottle of wine. "Push-on" capsules are made of heavy weight, plastic material, and many home winemakers prefer this type of capsule because they are easy to apply. The capsule is simply pushed onto the neck of the bottle.
Unlike push-on capsules, "heat-shrink" type capsules are made from thin plastic materials. They are available in a greater range of colors and finishes, and they are slightly less expensive. Heat-shrink capsules are placed over the neck of the bottle, and then heat is applied to shrink the plastic material tightly to the bottle. Large wineries pass the bottles through a heat tunnel to shrink the capsules in place. Home winemakers use electric heat guns, or they shrink the capsule by dipping the neck of the bottle in boiling water.
BOTTLE AGING
Time is required to age wine properly. Although considerable research has been done, no practical way has yet 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 in large storage containers, and small amounts of air are always present. Bottle aging takes place after the wine is bottled. Here, no air is present, and oxygen is not involved.
Most high quality dark red table wines are bulk aged from one to three years. After bottling, these wines are aged in the bottle for a year or more to develop a bottle bouquet. Very tannic red wines often require several years of bottle aging to reach maturity. Heavier white wines are usually bulk aged for several months and then aged in the bottle for an additional time. Aging in the bottle is best accomplished by placing the bottles on their sides in a cool, dark, quiet place.
Novice winemakers sometimes become very enthusiastic about their first few winemaking efforts, and they often consume their wines too early. Two cases of wine can be consumed in a short time, and many new winemakers exhaust their supply before the wine ever approaches maturity. This is one argument against making wine in five gallon water bottles. A 15-gallon beer keg holds six cases, and this is about the smallest size container suitable for home wine production. Of course, five-gallon glass bottles are handy for storing leftover wine.
SUMMARY
Dirty wine bottles are a potential source of contamination in the home winery. Dirty bottles should be washed and then placed in clean cartons. The cartons of clean bottles should then be stored in a clean, dry place.
All wine must be brilliantly clear and stable before it is bottled. Any blending should be done several weeks before bottling time. Early blending allows the winemaker to check the wine for several weeks to make sure the new blend is stable before bottling time.
Wines containing more than 1/4 percent residual sugar can restart fermenting 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. The right amount of sorbate must be added, and 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. Custom wine labels are easy to make using a home computer.
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