August 18, 2016


This week let's talk about sulfur. This rock with the sad, dirty aroma is one of the most talked about and least understood parts of winemaking.
Let's start at the beginning-2000 years ago, when laborers from small towns all over Sicily would rise in the middle of the night to make the trek up the mountain to the sulfur mines. In the dark, these roughhewn men would stack deposits of sulfur inside brick kilns built on the sloping hillsides. Once the kilns were full, powdered sulfur was spread over the top and set alight. Pale blue flames would lick the sides of the kiln until it reached 240 degrees, at which point the yellow rock would melt into a dark crimson liquid the color of blood and flow down the hillsides to be collected later.

The history of sulfur production is ancient and full of intriguing details (a flaming blue rock that bleeds?!) It was (and still is) an essential component in winemaking, as well as being used as an explosive, to bleach fabric, to fumigate houses, in rituals and many other applications. Much of the sulfur produced in places like Sicily was used by the Romans. They would burn sulfur candles inside wine vessels to fumigate and clean them. This practice which seems so ancient is still one of the most fundamental and powerful tools that winemakers have at their disposal. Large wineries use sulfur, small wineries use sulfur. Franzia box wine uses sulfur, Romanee-Conti uses sulfur. It's almost as much a part of winemaking as grapes are.

Lately though there are a lot of questions about sulfur and why it's included in winemaking. As a society it seems like we are moving away from blind acceptance of chemical manipulations and unnecessary additions to our food. It only seems natural that people would question why sulfur is added to wine, especially if you're one of the many people who suffer from headaches or flushing after drinking red wine. In addition (and as I've written about before wine bottles have no ingredient labels, but it does have a warning from the FDA about sulfur. It's not surprising then that people would be concerned about this one and only chemical listed on the bottle. As explained in a previous e mail though, don't fool yourself. Many industrial wines contain far, far more chemicals than sulfur alone and many of those can result in a host of symptoms that people generally just blame on sulfur.

As a quick aside, there also seems to be a generational (and maybe cultural) difference with the approach to sulfur. I had an experience as a wine rep with one of my customers, a Frenchman from Bordeaux named Emile. I came in for my weekly sales call one day and he had a head cold and so understandably didn't want to taste. I threw my wine bag over my shoulder and started to leave but he stopped me and asked what I had to pour. I gave him my bag and he rifled through it, eventually picking out a wine and asking me for a small pour. I obliged and rather than the normal sniff and swirl he took it straight to the head like a shot of vodka. He set his glass down and asked for another, did the same, then asked for another. After three shots of red wine he thanked me, blew his nose and said see you next week. I asked him why he choose that particular red wine and he said through his cold (and his French accent) that it was the bottle he assumed had the most sulfur in it and that it would help him get rid of his cold. Leave it to the French…

Back to the topic at hand- why do winemakers add sulfur in the first place? sulfur is a powerful antioxidant and antimicrobial. It kills yeast and bacteria but interestingly it's more active against bacteria than yeast (don't forget that it's a natural byproduct of fermentation). What this means is that the correct dose of sulfur can also allow you to avoid using commercial yeast in your wine. By adding the right amount you can kill off the bad bacteria, encourage the growth of the more robust wild yeast to help your wine through fermentation and kill off the less vigorous strains of wild yeast. This last point might not seem like much but it is. Being able to avoid commercial yeast in your wine is 10 times more important than avoiding sulfur from the standpoint of terroir.
Before we get too deeply into the why's and how's though, we need to understand how to talk about sulfur. Get ready to be bored, because bam! Here comes some science in your face. When you talk about sulfur in wine there are really three different terms-total sulfur, free sulfur and bound sulfur. Some portion of the sulfur binds to other chemicals in the wine and it becomes inaccessible-this is bound sulfur. Free sulfur is the amount that’s chemically available and free to work it's antimicrobial and antioxidant magic and total sulfur is…well…just what it sounds like. It's the total amount of sulfur, free plus bound sulfur equals total sulfur. To complicate things, not all of the free sulfur is actually available; some portion of it is inactive as bisulfite anion. I couldn't get my small mind to understand why this is, so if you have further questions you’re going to have to ask your teenager in chemistry class or your neighbor who works at the UW.

How much sulfur to add to wine depends on a lot of different factors. For instance filtered wine needs less sulfur in general but not filtering your wine is now considered essential to quality (this is the trumpet that Kermit Lynch has been blowing for decades) so as a winemaker you need to decide- do I add more sulfur or do I filter my wine? Most quality producers choose to add more sulfur. Another interesting fact about sulfur is that in wines with a lower PH level (generally cooler climate or higher acid wines) you have to add less total sulfur to arrive at the same amount of free sulfur. This is a double benefit, because not only do you have to add less sulfur in general but it’s also more efficient. The opposite of this is true as well-hotter climate, higher PH wines need more sulfur and the sulfur you add is less efficient. Washington winemakers take note…

The quality of your grapes determines how much sulfur you need to add as well. Damaged or rotten grapes are much more prone to oxidation so if you are harvesting your grapes by hand and carefully sorting, you won’t need to add as much sulfur. On the other hand if you're harvesting with a giant robot that throws everything in the bin including the pruning shears, then it follows that you're going to have to blast the resulting juice with huge amounts of sulfur. But "rotten" grapes includes those infected with Botrytis (otherwise known as noble rot). Botrytis is a fungal infection that shrivels the grapes and concentrates the sugar and is essential to some of the most famous sweet wines in the world such as Sauternes. The FDA allows for more than twice the amount of sulfur in these types of wines compared to dry wines. Part of the reason for this is that wines made from botrytized grapes are high in a compound that binds free sulfur. As a result you have to add enormous amounts of total sulfur to the juice and you may still end up without enough free sulfur to protect the wine. One interesting tidbit I learned while doing the research for this was that sulfur doesn’t actually protect the wine from oxidation, it binds with the aldehydes that are created as a result of oxidation so you don’t smell the result. Apropos of nothing, but interesting nonetheless.

Another broad category of wines that need more sulfur are white wines. White wines have less of the polyphenols that help protect from oxidation, so they need to be bolstered by sulfur to make up for this. They also need more sulfur if they are going to age well. Studies in Australia have shown that 10-15 mg/liter (at a PH of 3.1) of sulfur are needed in order for the wine to age well, and the PH levels are critical to the understanding of these studies. This opens a whole world of discussion about German wines and white Burgundy. Old school German wines were both sweet, high in acid and massively sulfited (Emile was probably looking for German Riesling in my bag back in the day…). These wines are so shut down from the sulfur that they need decades in some cases to emerge from their shells. This doesn't do much for consumers looking to drink the wines that night with their schnitzel, but if you find 20, 30 or 40 year old wines from these producers nowadays you can pretty much ensure that they will have held up well. As far as white Burgundy what does this mean for the premature oxidation debate? Is the trend towards less sulfur maybe contributing to the white wines of burgundy oxidizing faster? Are the wines getting higher PH levels as a result of warmer vintages? All interesting questions that we don't have time for in this email…

One thing we need to make time for in this email however is sulfur in what are known as "natural" wines. Natural winemakers are really the ones pushing the trend towards wines with little or no sulfur right now. The impulse for many of these winemakers is to create wines with zero additions. It's a worthy cause if done right, unfortunately it's very difficult to make a stable and clean wine without any sulfur at all. You have to understand the science and be impeccable clean in the winery. As the polemic wine importer Joe Dressner put it "the thing with the microscopes wasn’t bullshit…" It takes a lot of intelligence and knowhow to make a wine without any sulfur.
I had a discussion with one of the most respected winemakers in Chinon a few years ago at a natural wine tasting in France. He made the point that a guy who was a tractor mechanic a year ago can now be a "natural" winemaker. All he has to do is buy some juice before it’s sulfited, put it in his own tanks and wait to bottle it. Whether the wine is completely full of flaws and has no discernible terroir doesn’t seem to matter. On the other hand this respected winemaker has spent most of his life learning how to make wine from his father in a clean and natural way and their decision to add 1/2 a gram of sulfur before bottling is one that ensures that their wine tastes and smells like a classic bottle of Chinon by the time it makes it to the US. There is no mistaking it when you open their wine that you are experiencing one of the classic producers in the world and one of the best terroirs. The difference chemically between their wine and the tractor mechanic’s wine is 1/4 a gram of sulfur (and to be fair, many lifetimes of experience and hard work.) But the difference on the nose and in the glass is worlds apart as well.

According to the late Joe Dressner again, the winemakers that are zealots about making wine without sulfur are often the ones making the least interesting wines. Joe used to ask his producers to add a bit of sulfur to their wines since his customers in the US didn't have the necessary storage to protect these wines. This brings up one of the last but most interesting points about sulfur. Sulfite free wines need to stay at 57.2 F at all points in the supply chain. This was a stunning fact for me to read. In other words it's totally possible to make a sulfite free wine that is glorious and full of pure terroir, but you have to travel to the cellar door to buy them, get them home in the cold trunk of your car and into your own subterranean cellar. This means wines from the likes of Thierry Allemand, Jean Foillard, Stanko Radikon, Frank Cornellison and others could be made completely sulfite free and be the pure expressions of terroir and naturalness that everyone is striving for. The only way to enjoy them though is to own houses in Cornas, Morgon, Slovenia and Mount Etna respectively and a driver to go pick them up and deposit them quickly in the cellar of one of your many vast estates. It also means that you may read stories or reviews about these wines and how incredible the sulfite free versions are but they were most likely enjoyed at the estate they were produced, not here in the U.S.

Before we wrap up this incredibly long email (is anyone still reading this?) we have to get the perspective of the most important person in the wine industry - you, our dear readers. All of this hinges on your perception of sulfur and what you’re willing to spend your money on. While many people are quick to blame sulfur for just about any malady they feel, there are in fact legitimate concerns - namely for asthmatics. Some (but not all) asthmatics are very sensitive to sulfur and need to be careful about their intake. The aforementioned headaches and flushing can indeed be an asthmatic reaction to sulfur. There is an easy way to determine the culprit though. What I like to do is ask people if they eat any dried fruits such as raisins or apricots. If the answer is yes and they don’t suffer any adverse reactions, then sulfur is not likely the problem. Most dried fruit contains about 1000 parts per million of sulfur - 10 times that of a bottle of red wine. The answer people don't like to hear (but I must admit I sort of like telling them) is that it's probably that other evil byproduct of fermentation-alcohol. The flushing tends to just happen (especially with people of Asian and Norwegian descent) and the headaches…well…umm….that's a called a hangover. There's an easy way to avoid that.

In the end it's easy to understand why sulfur is so often maligned. This caustic substance, the brimstone of hell. This rock with what Primo Levi calls the "sad and dirty aroma" is a powerful and dangerous substance that needs to be handled carefully. It's been a part of humanity for as long as we've been digging in the earth. With the full palette of chemicals available to winemakers these days sulfur seems relatively innocuous by comparison. It is possible to make wine without sulfur and even preferable, but it's extremely difficult to do well and the resulting wine can't travel without being refrigerated. On the other hand the judicious use of a small amount of sulfur allows you to; avoid commercial yeast, use less chemicals in the wine, avoid filtering, and the wine ages better as a result. On top of all of that if you ever catch a cold, just do like Emile: take 2 or 3 shots of red wine, take a nap and voila! All better.
If you want to learn more about sulfur or any other aspect of science in winemaking you should read Jamie Goode's excellent book Wine Science (you could pretty much skip the chapter on sulfur however. I more or less cribbed the whole thing for this email).
Thanks for reading.


Thanks and we'll see you at the store

Noah Oldham
Wine Buyer
DeLaurenti Food & Wine

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