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| Grape growing, winemaking and wine maturation |
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| Bottling and packing |
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 Bottling is a process that can cause oxidation and/or damage a wine in other ways. For this reason and to ensure that the wine is not damaged after shipping from the winery, several items can be added to the wine before bottling.
Sulfur dioxide it is almost always added just before bottling. Sulfur is widely used in the winery. It destroys the bacteria and yeast that can cause spoilage. Since it combines readily with oxygen, it can also help keep wine fresh, and it can even reverse some of the ill effects of oxidation.
Other, less common additives include ascorbic acid (used for its antioxidant properties), sorbic acid, (to prevent refermentation), metatartaric acid (to prevent tartrate crystallization), potassium ferrocyanide (added to remove an iron or copper haze), citric acid (which can remove iron by combining with it) and calcium phytate, used for the same purpose. Finally, copper sulphate can be used to remove reduction, and gum Arabic can be used to stabilize the wine.
 At bottling, there are several possible procedures. The first is to bottle (very carefully!) wine that has been neither filtered nor fined. This is an option for winemakers that have been very careful. As long as the wine has been fermented to dryness and allowed to settle and then been racked, bottling without fining and/or filtration is possible. If any of these conditions have not been met, spoilage may occur.
Another option is to bottle the wine after cold sterile filtration. This is an absolute or membrane filtration through pores small enough to exclude yeast and bacteria. To accomplish this successfully, the bottling machines must be sterilized.
A third option is called hot bottling. This process involves heating the wine to 54° C, bottling the wine and letting it sit and cool at room temperature. This eliminates bacteria and yeast without pasteurization and avoids the need for sterile conditions.
Another process that can be done at bottling is pasteurization. One form is tunnel pasteurization. Here the wine is bottled and the bottles are raised to 82° C for fifteen minutes. Flash pasteurization uses higher temperatures but shorter time. Here the wine is raised to 95° C, but only for one or two seconds.
One of the last links in the chain before the consumer is the cork. Cork failure ruins more wine today than any other cause. Estimates vary enormously, but most reasonable observers estimate the quantity at about 5% of all production. This means that one bottle in twenty is spoiled by an unacceptable closure.
Leaky corks can lead to infiltration of oxygen or (worse) acetic bacteria that can lead to volatile acidity. A more prevalent problem, however, is TCA contamination or corkiness, as outlined in the section on wine faults. TCA is a compound that develops when mold in the corks comes in contact with chlorine bleach during the cleaning process. It creates a pungent aroma that ruins the wine.
The level of TCA contamination depends in part on how the cork was manufactured and on the quality control – expensive corks have fewer failures than the cheap ones. Alternatives to cork have been tried, and although many of these alternatives reduce or eliminate cork taint, they are not trouble free – every system has its own set of problems.
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Wine Regions of the World
