Filtration and Fining: Important Tools, Not Dirty Words
By Jeff Morgan, West Coast editor
Not long ago I enjoyed a magnificent Inglenook Cabernet Sauvignon Napa Valley 1958. It was still full of life, silky-smooth, complex and rich with ripe fruit flavors. Back in the 1950s, standard winemaking procedure at Inglenook included filtration with diatomaceous earth, as well as significant fining with egg whites and gelatin.
The 1958 bottle, taken directly from the cellar at Niebaum-Coppola Estate Winery (formerly Inglenook), is possibly the greatest California Cabernet I have ever drunk. And if that's what filtration and fining can do, then I'm a firm believer in them--at least when necessary.
In fact, I'm really tired of seeing "unfined" and "unfiltered" used on certain wine labels as a selling point. Wineries only create public confusion by associating those two words with quality. There are plenty of lousy, stinky, cloudy, unstable, unfiltered wines on the market today that really could have benefited from a good sterile filtration.
Now don't get me wrong. I'm not recommending the wholesale fining and filtration of all wines. If a winemaker can make a delicious and chemically stable wine without filtration, then he should be commended. Both filtration and fining run the risk of eliminating precious flavor components along with the undesirable elements they are meant to remove.
But filtration and fining are both time-honored winemaking techniques that, when properly applied, can actually improve a wine and give it greater longevity for cellaring.
Let's look at filtration of the spoilage yeast Brettanomyces, a bedeviling microscopic beast that haunts many wineries and wine barrels. In small doses, Brettanomyces can add complexity and interest to a red wine. But too much can serve up overwhelming barnyard aromas and flavors, ultimately ruining an otherwise fine wine. These "off" qualities can increase with bottle age, particularly if storage conditions are less than perfect. Sterile filtration, which employs a very finely meshed membrane filter, can eliminate or greatly reduce this rogue yeast, allowing a wine's better attributes to shine.
Perfectly delicious white wines can also suffer disastrous consequences should they need filtration yet not receive it. Many Chardonnays, for example, are bottled today with a bit of residual sugar to enhance mouthfeel and flavor. Or sometimes a wine simply stops fermenting, its yeast spent, before all its grape sugar has been converted to alcohol.
In both cases, dormant yeast not removed by filtration can conceivably awaken inside a bottled wine containing residual sugar and recommence fermentation. The resulting by product of this unwanted fermentation, carbon dioxide gas, has been known to shatter bottles on wine shop or cellar shelves.
A similar effect can occur from unfinished malolactic fermentation. This commonly occurring bacterial fermentation transforms tangy malic acid to creamier lactic acid. It produces no alcohol, but does generate potentially explosive bubbles nonetheless. Sterile filtration is a key tool in preventing this scenario.
Red wines tend to be more stable than whites and can be more readily released in an unfiltered state. Most white wine, in America at least, is filtered, although notable exceptions such as the Kistler and Marcassin Chardonnays do exist. But even a purist like Steve Kistler would resort to filtration if necessary to preserve the integrity of a wine.
And what about fining? What is it anyway? Fining materials such as egg whites, gelatin, beef blood (not legal in the United States, but once commonly used in Europe) and bentonite clay, an extremely fine powder, act like magnets: They bond with certain elements--astringent tannins or potentially cloudy particulate matter--weigh them down and cause them to drop out of solution.
Not only can they smooth out rough tannins that obliterate flavors, but they may also eliminate bitter or malodorous components. When used correctly, fining agents can most definitely improve a wine. Used excessively, however, they can strip away all its beauty. That's why winemakers do fining trials on tiny amounts of wine before deciding what dose to use.
I wonder if that 1958 Inglenook would have tasted better without fining or filtration. Perhaps. But its greatness lay in its grapes, not in its processing or lack thereof. Wisely, in 1958, the Inglenook winemakers took those precautions they felt necessary to insure their wine's longevity.
The greatest challenge for any winemaker is to allow the grapes to speak clearly. If it can be done without fining or filtration, so much the better. But blind adherence by winemakers--or consumers--to a rigid noninterventionist philosophy will surely yield missed opportunities.
Let's buy and drink wines because they taste good. Claims of "unfined" and "unfiltered" aren't worth the paper they're printed on.
This column, Unfiltered, Unfined, features the opinionated inside scoop on the latest and greatest in the world of wine, brought to you each Monday by a roster of Wine Spectator editors. This week we hear from West Coast editor Jeff Morgan. To read past Unfined, Unfiltered columns, go to the archives. And for an archive of senior editor James Laube's columns, visit Laube on Wine.