As a follow-up to my recent post about “natural winemaking,” I asked our esteemed panel of winemakers for their views on the role of sulfur dioxide in making and raising wines.
“Natural winemaking” is an issue of great interest these days to many consumers, not least because many wine journalists, retailers and sommeliers are touting its benefits. But they also may be tolerating wine flaws that might have been prevented by judicious use of sulfur dioxide. What do YOU view as the most important role of sulfur products in the winemaking and aging process—IF there is one?
Brian O’Donnell, Belle Pente (Oregon). It may be stating the obvious, but for me the role of SO2 is to avoid the aforementioned flaws that are often apparent in “no added sulfites” wines. These flaws result from oxidation and undesirable microbial activity that, as you say, can easily be inhibited by a moderate dose of sulfites at bottling. Although I embrace the philosophical intent of “no added sulfites” wines, I am not willing to compromise quality for the dubious perceived benefits of following that path.
Matt Donaldson, Pegasus Bay Winery (Waipara, New Zealand). During winemaking and élévage, I consider SO2 an important tool as it plays both anti-microbial and anti-oxidation roles. We get so many benefits from its use, it would be impossible to mention them all but I’ll list a few. First, SO2 binds up acetaldehyde. If riesling didn’t have an addition of SO2 post-ferment, the acetaldehyde produced by the yeast would completely submerge the delicate aromas and terroir character.
With sauvignon blanc, methoxypirazines [a class of chemical compounds that produce odors, often undesirable] are, unfortunately, quite resistant to oxidation. Thiols, on the other hand, which give our preferred sauvignon blanc characteristics), are very oxidizable. This is why most NZ producers add SO2 at harvest in the vineyard. We don’t go to that extreme but we do add some SO2 to the juice tray and protect the thiols with an SO2 addition post-ferment.
We add about 80 ppm [parts per million] to our pinot vats so we get a good length of cold soak. This also helps us select the preferred natural yeasts. We add 30 ppm to our chardonnay juice once it’s in the tank for the same purpose. This early SO2 addition also means that the pinot noirs are less likely to go through MLF [malolactic fermentation] straight after primary fermentation.
Our chardonnays go through a natural MLF in spring but in most vintages we don’t want them to go all the way through, so when we think the balance is right we arrest the MLF by an addition of 80 ppm of SO2.
Our pinots also go through a natural spring MLF but we usually don’t add SO2 until just before the next vintage as our cellar is relatively cool and the wines are still charged with CO2, which gives them some degree of protection. We like to leave them for another six months on average in barrel and the SO2 addition allows us to do this (by protecting the wine from oxidation & brett) without compromising the delicate aromas which are an integral part of the terroir expression.
Since the advent of sterile filtration, I see the role of SO2 post-bottling as mostly anti-oxidative. Our philosophy is to add just enough SO2 so that the wine has enough time to evolve gracefully in the bottle. The free SO2 gradually reduces over time, which is part of the bottle-age character.
If the aim of natural winemaking is to better reflect the terroir, then hopefully the terroir isn’t masked by oxidation, brett, VA or refermentation in the bottle. Unless of course the winemaker considers these characters to be part of the terroir.
The term “natural winemaking’ is a strange one. I don’t consider our methods unnatural—maybe ultranatural, or supernatural? Yes, I like that. Let’s try to coin that term “supernatural winemakers”: maybe I’ll trademark it.
Andy Erickson, Screaming Eagle, Dalla Valle, Arietta (Napa Valley, California). Sulfur is the most natural way to prevent wine from turning to vinegar, which, as a winemaker, I feel is pretty important. I would welcome debate on the subject—in my eyes smart use of sulfur is in itself a part of “natural winemaking.” A well-aged wine bottled without sulfur and without filtration is (or will eventually become) vinegar.
Ken Forrester, Ken Forrester Wines (Stellenbosch, South Africa). In this age of clean stainless steel fermentations with powerful commercial yeasts, one really does need to consider carefully the role of sulfur: it’s not friendly stuff! It will bind with many of the flavor compounds and reduce the attractions of any wine, so we have to interrogate just how much we need to use.
One of the age-old habits is pushing an old piece of bark into the bottle neck, commonly known as a cork! Now this cork is basically hollow; therefore it is filled with air and hence oxygen, and this represents the major threat of oxidation to a newly bottled wine. So as a matter of course over the last 200 years winemakers who brazenly plunge this “oxygen plug” into their carefully crafted fine wines hasten to “protect” the wine from this oxygen by adding up to 50 or 60 parts per million of free sulfur at bottling. This naturally really does almost destroy the beautiful fruit of the wine and sets it back five or six years in the bottle, so that when it finally emerges, the incorrect assumption is, “look how well the cork has aged the wine!”
Such utter nonsense. If you had used a smart, efficient Stelvin screwcap closure you wouldn’t have needed to almost destroy the wine with sulfur in the first place! Technically you can now add less than 50% of the “normal sulfur addition.” Honestly, this is some crazy logic. Using an oxygen bomb (cork) so that you have to use sulfur to protect the wine? Are we nuts or what?
Lighten up on the sulfur, and use a reliable closure without having to destroy your wine: go the smart route with reliable screwcap technology.
Half the free sulfur at bottling is a fine thing!
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