Unfiltered is a word that many of you have probably seen on a wine label. But do you know what it means? Are unfiltered wines better than filtered wines? Or, vice versa? The word unfiltered on a wine label means that the wine was bottled unfiltered. Most wines go through some level of filtration before bottling. The reasons are twofold.
Firstly, most wine consumers expect the wine to be clear and bright and not in anyway cloudy or hazy, and secondly, to prevent any unwanted second fermentation and/or microbial spoilage in the bottle.
What is Wine Filtration?
Wine filtration is the physical process whereby a wine is passed through a filter in order to remove any solids in the wine that are visible to the naked eye and, if necessary remove any unwanted micro-organisms such as yeasts and/or bacteria.
Rendering the Wine Clear and Bright
Usually a loose earth filtration is all that is needed here. This is particularly important with white wines. With red wines, a little haze may be more acceptable to the consumer. Either way filtered or unfiltered the wine is not faulty. Most fine red wines, that have been fermented fully dry and barrel aged do not even need this additional filtration as they will have more or less self- filtered over time, and being fully dry will remain stable once in the bottle
Maintaining Microbial Stability
The more serious issue is with wines that have not been fermented fully dry, as is the case not just with sweet dessert wines, but also with almost every 'popular' entry level and or mid-market wine. While not overtly 'sweet' many of these wines contain up to 6-10g/l residual sugar. Any remaining / wandering yeast or bacteria cells will have a field day on the sugars, causing unwanted second fermentations and microbial spoilage inside the bottle. Not something that any wine consumer likes to find!
Such wines go through a more sever filtration process called micro or sterile filtration to remove any remaining yeasts and/or bacteria before the wine is bottled ensuring a safe, stable wine.
Filtration - A Controversial Topic
Filtration is a very controversial topic among the winemaking community. Some see it as a normal step, that when carefully executed has no downside, while others maintain that any type of filtration (even loose) strips the wine of some of its integrity.
The bottom line is that there are as many high quality wines that are filtered, as there are unfiltered. So rather than read 'unfiltered' as a sign of higher quality I see it more as a sign of the winemaker's philosophy.
Mary Gorman-McAdams, MW (Master of Wine), is a New York based wine educator, freelance writer and consultant. In 2012 she was honored as a Dame Chevalier de L'Ordre des Coteaux de Champagne
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