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.Stabilizing a light, fruity white table wine is not trivial.Light, fruity wines can be damaged easily by overprocessing, excessive handling or oxidation, and producing good long term bottle stability without reducingthe quality of a delicate wine requires considerable winemaking skill.Occasionally, a winemaker bottles a wine without doing stability tests.The wine has been brilliantly clearfor several months, so the winemaker assumes the wine is stable.A few weeks after bottling, the winedevelops a bad haze or drops an ugly sediment in the bottles.Now the winemaker has little recoursebecause un-bottling, treating and re-bottling would destroy wine quality.Bottling unstable wine can be adiscouraging event for any winemaker, and it can be an economic disaster for a commercial producer.Cold StabilizationPractically all new wine contains excessive quantities of potassium bitartrate, and the tartrate precipitates outof cold wine as crystals or hazes.All white and blush wines require cold stabilization before bottling, andmost commercial producers cold stabilize their red wines as well.Wine can be effectively cold stabilized inseveral ways.A few large wineries use ion exchange columns to remove potassium from the wine.Ionexchange columns are filled with resin and work on the same principle as domestic water softeners.Thistype of wine cold stabilization requires large, expensive equipment, and a trained chemist is needed toestablish the proper operation of the exchange column.However, once the equipment is operating, the ionexchange method is a fast and economical cold stabilization process.Unfortunately, wine quality can bereduced when the ion exchange method is used inappropriately.Smaller wineries use a much simpler method to stabilize their wines.The wine is cooled to about 2795 degrees and held at this low temperature for a week or two until the excess potassium bitartrateprecipitates.This method of cold stabilizing wine also has advantages and disadvantages.Lowtemperatures are beneficial to new wine in several ways.Besides causing the potassium bitartrate toprecipitate, the cold temperature helps other unwanted materials settle out of the wine.Sometimessuspended pectin and gums can be removed by chilling the wine.In addition, several days of lowtemperature storage can be helpful in developing long term wine stability.Unless the wine is carefully handled, considerable oxygen can be absorbed while the wine is cold.Theoxidation problem can be managed by purging wine containers with an inert gas, keeping the containerscompletely full and by maintaining adequate levels of sulfur dioxide in the wine.The high cost of energyneeded to operate the large capacity refrigeration system raises production costs, and many wineries usespecially insulated tanks to stabilize their wines.Tartrate crystals also form in red wines, but the dark color obscures small deposits of tartrate crystals.Redwines are not chilled before serving, so a haze seldom forms.Often the tartrate crystals in red wines arefound adhering to the cork, and the crystals are removed when the cork is pulled.Tartrate crystals are notso noticeable in red wine, so a few smaller wineries and many home winemakers do not bother to coldstabilize their red wines.However, most commercially produced red wines are cold stabilized before beingbottled.Hot StabilizationCommercial wine is shipped long distances in warm weather, and under these conditions, protein instabilitycauses hazes to form in white or blush wine.Protein hazes are very unsightly, and the wine industryconsiders excess protein removal an indispensable treatment for all white and blush wines.Excess protein is not difficult to remove from most wines, but sometimes Sauvignon Blanc wines can bedifficult to stabilize completely without damaging aromas and flavors.The standard treatment for all newwhite and blush wines is to fine with bentonite.The bentonite fining can be done anytime during thewinemaking process, but the procedure is more efficient when the bentonite fining is done after the new winehas been rough filtered.Nevertheless, many winemakers find it more convenient to stabilize their wines byremoving the protein earlier in the winemaking process (see below).Bentonite additions rang from one to ten pounds per thousand gallons of wine.However, high dose ratescan strip desirable flavors, so bench testing should always be done to measure the minimum quantity ofbentonite needed.The treated wine is allowed to settle for a week or so before it is racked.Tannin in red wine reacts with protein and causes the protein to precipitate out of the wine duringfermentation.Little protein remains at bottling time, so protein hazes are seldom a problem in red wine.Combined Hot & Cold StabilizationAll white and blush wines require both hot and cold stabilization treatments, and some winemakers combineboth stabilization procedures into a single operation to reduce handling.First, the wine is fined withbentonite, and then the wine is immediately chilled to about 27 degrees.The wine is held at the coldtemperature for a week or so while the tartrate precipitates.When the excess tartrate is gone, the cold wine96 is racked or filtered off the bentonite and tartrate lees.This combined procedure has some advantages.The tartrate crystals settle on top of the fluffy bentonite lees forming a crusty layer, and the wine is mucheasier to rack off the compacted lees.Both procedures are accomplished in a single winemakingoperation, so labor is reduced.Wine manipulation is reduced, and the risk of wine oxidation is reduced.Finishing White WinesMany of the desirable qualities of light bodied, white table wines come from the characteristics of thegrapes.These wines are only a few months old when bottled because lengthy aging destroys the desirablefruit qualities.For example, light fruity Riesling wine is often finished in the following way.Afterfermentation, the free sulfur dioxide content is adjusted to about 30 milligrams per liter, and then the wine ishot and cold stabilized.After cold stabilization, the acid level is adjusted (if necessary), and the wine isallowed to rest for a few weeks.Then the wine is critically evaluated, and any other necessary adjustmentsare made.If large adjustments were made, the winemaker would test the wine again for both hot and coldstability.At bottling time, the free sulfur dioxide content of the wine is raised to about 30 milligrams per liter.Rieslingwine normally contains residual sugar.Any residual sugar may cause fermentation to restart, so a sterilefilter would be used to remove all of the yeast cells from the wine when it is bottled.Most homewinemakers do not have sterile filtration equipment, so they use a different method to leave residual sugar inwine.Home winemakers add potassiumsorbate to the wine.The sorbate stabilizesthe wine by preventing the yeast cells from1.A bentonite fining is done to removemultiplying.All wines containing residualexcess protein and hot stabilize the wine.sugar are carefully watched for several2.The wine is chilled to about 27 degrees and held atweeks after bottling because thethe low temperature for several days to removewinemaker wants to be sure the wine isexcess tartrate crystals and cold stabilize the wine [ Pobierz całość w formacie PDF ]
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.Stabilizing a light, fruity white table wine is not trivial.Light, fruity wines can be damaged easily by overprocessing, excessive handling or oxidation, and producing good long term bottle stability without reducingthe quality of a delicate wine requires considerable winemaking skill.Occasionally, a winemaker bottles a wine without doing stability tests.The wine has been brilliantly clearfor several months, so the winemaker assumes the wine is stable.A few weeks after bottling, the winedevelops a bad haze or drops an ugly sediment in the bottles.Now the winemaker has little recoursebecause un-bottling, treating and re-bottling would destroy wine quality.Bottling unstable wine can be adiscouraging event for any winemaker, and it can be an economic disaster for a commercial producer.Cold StabilizationPractically all new wine contains excessive quantities of potassium bitartrate, and the tartrate precipitates outof cold wine as crystals or hazes.All white and blush wines require cold stabilization before bottling, andmost commercial producers cold stabilize their red wines as well.Wine can be effectively cold stabilized inseveral ways.A few large wineries use ion exchange columns to remove potassium from the wine.Ionexchange columns are filled with resin and work on the same principle as domestic water softeners.Thistype of wine cold stabilization requires large, expensive equipment, and a trained chemist is needed toestablish the proper operation of the exchange column.However, once the equipment is operating, the ionexchange method is a fast and economical cold stabilization process.Unfortunately, wine quality can bereduced when the ion exchange method is used inappropriately.Smaller wineries use a much simpler method to stabilize their wines.The wine is cooled to about 2795 degrees and held at this low temperature for a week or two until the excess potassium bitartrateprecipitates.This method of cold stabilizing wine also has advantages and disadvantages.Lowtemperatures are beneficial to new wine in several ways.Besides causing the potassium bitartrate toprecipitate, the cold temperature helps other unwanted materials settle out of the wine.Sometimessuspended pectin and gums can be removed by chilling the wine.In addition, several days of lowtemperature storage can be helpful in developing long term wine stability.Unless the wine is carefully handled, considerable oxygen can be absorbed while the wine is cold.Theoxidation problem can be managed by purging wine containers with an inert gas, keeping the containerscompletely full and by maintaining adequate levels of sulfur dioxide in the wine.The high cost of energyneeded to operate the large capacity refrigeration system raises production costs, and many wineries usespecially insulated tanks to stabilize their wines.Tartrate crystals also form in red wines, but the dark color obscures small deposits of tartrate crystals.Redwines are not chilled before serving, so a haze seldom forms.Often the tartrate crystals in red wines arefound adhering to the cork, and the crystals are removed when the cork is pulled.Tartrate crystals are notso noticeable in red wine, so a few smaller wineries and many home winemakers do not bother to coldstabilize their red wines.However, most commercially produced red wines are cold stabilized before beingbottled.Hot StabilizationCommercial wine is shipped long distances in warm weather, and under these conditions, protein instabilitycauses hazes to form in white or blush wine.Protein hazes are very unsightly, and the wine industryconsiders excess protein removal an indispensable treatment for all white and blush wines.Excess protein is not difficult to remove from most wines, but sometimes Sauvignon Blanc wines can bedifficult to stabilize completely without damaging aromas and flavors.The standard treatment for all newwhite and blush wines is to fine with bentonite.The bentonite fining can be done anytime during thewinemaking process, but the procedure is more efficient when the bentonite fining is done after the new winehas been rough filtered.Nevertheless, many winemakers find it more convenient to stabilize their wines byremoving the protein earlier in the winemaking process (see below).Bentonite additions rang from one to ten pounds per thousand gallons of wine.However, high dose ratescan strip desirable flavors, so bench testing should always be done to measure the minimum quantity ofbentonite needed.The treated wine is allowed to settle for a week or so before it is racked.Tannin in red wine reacts with protein and causes the protein to precipitate out of the wine duringfermentation.Little protein remains at bottling time, so protein hazes are seldom a problem in red wine.Combined Hot & Cold StabilizationAll white and blush wines require both hot and cold stabilization treatments, and some winemakers combineboth stabilization procedures into a single operation to reduce handling.First, the wine is fined withbentonite, and then the wine is immediately chilled to about 27 degrees.The wine is held at the coldtemperature for a week or so while the tartrate precipitates.When the excess tartrate is gone, the cold wine96 is racked or filtered off the bentonite and tartrate lees.This combined procedure has some advantages.The tartrate crystals settle on top of the fluffy bentonite lees forming a crusty layer, and the wine is mucheasier to rack off the compacted lees.Both procedures are accomplished in a single winemakingoperation, so labor is reduced.Wine manipulation is reduced, and the risk of wine oxidation is reduced.Finishing White WinesMany of the desirable qualities of light bodied, white table wines come from the characteristics of thegrapes.These wines are only a few months old when bottled because lengthy aging destroys the desirablefruit qualities.For example, light fruity Riesling wine is often finished in the following way.Afterfermentation, the free sulfur dioxide content is adjusted to about 30 milligrams per liter, and then the wine ishot and cold stabilized.After cold stabilization, the acid level is adjusted (if necessary), and the wine isallowed to rest for a few weeks.Then the wine is critically evaluated, and any other necessary adjustmentsare made.If large adjustments were made, the winemaker would test the wine again for both hot and coldstability.At bottling time, the free sulfur dioxide content of the wine is raised to about 30 milligrams per liter.Rieslingwine normally contains residual sugar.Any residual sugar may cause fermentation to restart, so a sterilefilter would be used to remove all of the yeast cells from the wine when it is bottled.Most homewinemakers do not have sterile filtration equipment, so they use a different method to leave residual sugar inwine.Home winemakers add potassiumsorbate to the wine.The sorbate stabilizesthe wine by preventing the yeast cells from1.A bentonite fining is done to removemultiplying.All wines containing residualexcess protein and hot stabilize the wine.sugar are carefully watched for several2.The wine is chilled to about 27 degrees and held atweeks after bottling because thethe low temperature for several days to removewinemaker wants to be sure the wine isexcess tartrate crystals and cold stabilize the wine [ Pobierz całość w formacie PDF ]