Wine Clarification
Wednesday, January 2, 2008 at 01:17PM ![]()
Immediately after fermentation, wine contains particulate matter in suspension and unstable compounds that could, over time, affect the wine adversely. Methods of clarification (removal of unwanted substances) include the following:
RACKING
If the wine is allowed to rest in a stationary container (such as a barrel) heavier substances will eventually settle at the bottom. Racking refers to draining or siphoning the wine from one container to another, leaving the sediment behind in the first vessel. This is the simplest and gentlest method.
FINING
New wine may contain unstable compounds that are not heavy enough to be removed by racking alone. These can eventually bond with other substances in the wine, creating cloudiness or haze. Unstable, astringent components – principally excess tannins – can bond with the proteins in saliva, creating the dry, gritty sensation in the mouth associated with tannic wine.
Fining occurs when an agent is introduced that will bond electrochemically with undesired compounds (flocculation), rendering them heavy enough to be racked out (the racking process will eliminate the fining agent as well.) A number of different fining agents have been used historically, and various agents are still used depending on what the winemaker wishes to eliminate; in modern winemaking one may find egg whites, casein, isinglass and bentonite used frequently. Fining is not always necessary, but under some circumstances it can significantly improve the wine.
It has been argued that fining agents should be covered by labeling regulations. Most people in the wine industry believe that this would only create confusion because the fining agents are no longer present in the finished wine. I know of no instances of consumers being adversely affected by fining agents, due to allergy or any other reason, but it is difficult to demonstrate conclusively that the wine will never contain any trace of these agents, and some may object to the use of animal products in food production in general (the egg whites are from chicken eggs, casein is derived from milk products and isinglass is made from the swim bladders of fish. Bentonite is a kind of clay, which is usually mined.)
It should be emphasized that fining is a very old, traditional practice, used throughout the winemaking world.
FILTRATION
There are a number of different types and grades of filters used in winemaking, depending on the specific goal (that is, depending on what the winemaker wants to eliminate.) Like fining, filtration is not always necessary, and excess filtration can strip away substances that contribute to the wine’s quality, so the process is sometimes criticized. Most winemakers believe, however, that the appropriate use of filtration will not detract from the wine and can sometimes significantly benefit the finished product.
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