stability without SO2: why and how


I’ve been reading through parts of your book and your responses so far here, and I see that you’ve mentioned making a red wine without SO2 that is stable for quite a while. I’m wondering why you wanted to try such a thing, how you achieve such stability without SO2, and how long this wine can generally be in the bottle without oxidizing. I understand that the “how” could be a very long response (it looks like you teach entire courses on the subject), so an extremely general outline is fine, then I can ask followup questions if I have them. I’m particularly interested in whether or not you sterile filter such wines as you are clear about thinking that process is not generally good for reds. Thanks!


Two points to begin. First, I don’t subscribe to the health arguments. Since the human body produces a gram of sulfites per day – ten times as much sulfites as you find in a bottle of wine – how can there be an allergic reaction to sulfites? And second, there are many technical methods to make wine without sulfites – pasteurization, as is done for Japanese sake, to name one. That’s not my interest.

I’m interested in why the Romans planted all those grapes. I’m interested in why Robert Louis Stevenson called wine “bottled poetry” and Franklin’s definition of wine as “proof that God loves us and desires us to be happy.” Conventional wine doesn’t occur to me like that. I got to wondering, as a winemaker, what I was missing.

In his classic “Gods, Men and Wine”, William Younger proved to my satisfaction that although the Romans had access to sulfites (“blue smoke”), for some reason they didn’t use them in wine. My colleagues today poo-poo this by asserting that all Roman wine was full of lead or some other equally unsupported horseshit – they just can’t believe the possibility that 1,000 years of wines were made throughout the European continent without their beloved preservative. And believe you me, I know a lot of conventional winemakers who have had wines spoil by failing to maintain the sulfites.

But what if the initial addition of sulfites at the crusher (combined with bleach in the cellar, stainless steel, inoculated super-yeasts, inert gas and other draconian measures) destroys wine’s natural immune system? What if the principles the Germans introduced just after WWII and UC Davis has pushed over the last 40 years actually cause spoilage? What if Brettanomyces spoilage is in reality a hospital disease? Sounds like our contemporary pill-popping medical spiral, doesn’t it?

I asked Paul Frey, Tony Norskog and Gideon Beinstock if their no sulfites wines had much Brett – they all said it was a minor matter. I got to suspecting that Brett is a hospital disease – that the draconian sanitation and use of preservatives was killing everything else and clearing the way for a one-microbe spoilage potential. Maybe if we let the beneficials alone, they would control the bad guys. It’s just Integrated Pest Management applied to the cellar – simple common sense, really.

To be safe, I began with a wine that could serve as its own preservative, one that would consume oxygen and oppose a microbial takeover on its own, and also a varietal type for which microbial complexity might be regarded as a plus. I conceived of a three-pronged approach which I call IBM (Integrated Brett Management) which advocates 1. “Nutrient Desert,” i.e. encourage a healthy fermentation which diminishes both sugar and micronutrients to low levels.
2. “Aromatic Integration through Refined Structure.” I use early micro-oxygenation to build a tannin soufflé which knits complex microbial elements into a coherent complex single voice so they come off as soulful rather than as spoilage.
3.”Achieve Microbial Balance” by encouraging a diverse microbial ecology which doesn’t favor any one organism. This requires considerable time in a warm cellar (60-65F). As you have deduced, my goal is to have everything happen at the winery so I don’t have to sterile bottle and disrupt structure.

I decided to work with a high altitude syrah which had a lot of reductive strength from two sources: tannin and minerality. Raw unpolymerized tannin has the ability to gobble tremendous quantities of oxygen when wine is young. A beneficial side effect of micro-oxygenation is the creation of a rich, light structure which integrates aromas. Oxygen is the wire whisk in creating a tannin soufflé. This is going to keep the wine from smelling spoiled later on when the microbes have their party.

Paradoxically, working properly with oxygen doesn’t oxidize the wine – rather it increases its ability to take up more oxygen. The chemistry of phenolic polymerization is well understood, and in this case, Vern Singleton’s 1986 paper on the vicinyl diphenol cascade explains why polymerizing tannins become more reactive than their precursors, and why sulfites short-circuit this reaction to a great degree.

According to Claude Bourgignon, organic practices to promote living soil result in the formation of a symbiotic relationship between grape rootlets and mychorrhizal fungi which permits the uptake of many trace minerals grapes alone can’t take up. It’s easy to taste the difference between wine grown in living soil vs one where pesticides and herbicides are employed excessively – the latter have no finish, and the former have a lively energy on the back palate. I see this difference between rieslings from the Mosel and those from California and Australia, and I think it accounts for the ability of the former to age ten times as long despite having no tannin.

In 2001, I selected an organically grown (though they’ve never bothered to certify) syrah from Renaissance Vineyards, a tannic monster grown at 2400 feet, for an experiment. We picked ripe but not overripe, micro-oxed for a big fine structure, carefully leaving enough grip to age well, and let the microbial equilibrium do what it wished. In 2002 we repeated the experiment.

In 2003 we stopped experimenting. The wines without sulfites were so much better that we went that way 100% sulfite-free on our new Roman Syrah. We’re now on our 4th vintage sulfite-free, and the wines are magnificent – full of mystery and complexity, sort of like Barberesco.

You have to try them to get the gist. Unfortunately, only my library stash remains, and 2006 was the last vintage I had access to this fruit. You would need to be very nice to me so we could share a bottle. The good news is that in 2010, Jake Stephens granted me permission to make sulfite-free wines experimentally for Diamond Ridge Vineyards. When the 2010 Two Jakes Roman Reserve Cab Franc made Dan Berger’s list of the top 100 wines in the United States, Jake let me expand the program to Merlot and Cabernet Sauvignon from his extraordinary Lake County site, similar in soil and altitude to Renaissance.

I am developing a method that measures the rate of a wine’s oxygen reactivity, with some startling early results. It turns out that this rate varies about a thousand-fold, with weak whites taking up less than 0.1 ppm per day, and aggressive young reds consuming 1 ppm per hour! When SO2 is added, it actually drops the uptake rate by a factor of 12. This is because it short-circuits the phenolic oxidation reaction I describe in Chapter 6.

The bottom line is that with sulfite-free reds, the problem is not oxidation but rather reduction. It is not a question of whether they can age, but how many years will they take to come around (at least five). These are love-it-or-hate-it wines which test one’s ability to look at wine afresh. If you grow up on American cheese and the occasional Vermont cheddar, you might have a hard time with an unpasteurized Epoisse, which really does smell like dog-doo, but in a good way. Right…

The question of ageability begs for context. I can only testify that when done right, these wines do not simply fall into aldehyde, browning and VA, and for the more adventuresome palates, can delivered transporting excitement rarely experienced in conventional sulfited wine.

I see why the Romans did it this way. Say you’re a centurion in Gaul. Everybody hates your guts. So your best shot is to invite the local elders to dinner and treat them to the civilized good life only a stable government can provide. After the steam bath, you feed them wonderful things that require a long time and a lot of expertise to produce. Olive oil and stone oven baked bread. Artisanal cheeses. And wines so expressive and exotic, with so much more to offer than the crappy beer they’ve been brewing, that on the way home, one of them observes “Maybe we won’t stab them in their beds tonight.” This formula worked so well that even today, the vineyard of Europe is a map of the Roman Empire.

For the winemaker, high-ticket (the Roman Reserve CF is $50) sulfite-free wines require a remarkable vineyard site and careful stewardship at every stage. Like climbing Mt. Everest without oxygen, they are for experts and fools exclusively. I now have 13 successful vintages under my belt, and although most of my wines are still sulfited, these I consider this realm the pinnacle of my postmodern practice. Boring it ain’t.

"I see why the Romans did it this way. Say you’re a centurion in Gaul. Everybody hates your guts. So your best shot is to invite the local elders to dinner and treat them to the civilized good life only a stable government can provide. After the steam bath, you feed them wonderful things that require a long time and a lot of expertise to produce. Olive oil and stone oven baked bread. Artisanal cheeses. And wines so expressive and exotic, with so much more to offer than the crappy beer they’ve been brewing, that on the way home, one of them observes “Maybe we won’t stab them in their beds tonight.”


Love this thread! Yes I agree…the less sulfites the better! I’d much rather eat Epoisse than any cheddar.
But really, you know I bottle my reds with far less sulfites than UCD recommends, that they barrel age without any manipulation and that really they taste so much better after opening up for a day or two after the bottle is uncorked…How does that reason with the philosophy that wine reacts so badly to oxygen.
Reduction, as you say, is the key to this universe. Make the wine in a reductive manner, with little exposure to oxygenation and guess what, oxygen is really not the bad guy. It takes less sulfites to stabilize the wine and it doesn’t kill the aromatics and the wine and the wine handles all the other intangibles so much better…
You should come visit sometime…the mountains are beautiful right now:) We could taste thru some barrels. It has been awhile!

Anna Marie

Thanks so much for the detailed response, Clark! Also, thanks for weighing in, Anna Marie.

One followup question comes to mind: how are you measuring the rate of a wine’s oxygen reactivity? I’ve never heard of such a thing. I would think it could be a huge game changer for when and how much SO2 is added for those who use it. Do you see any specific applications for the process in the future?

Yes, you said a mouthful. A huge game changer made possible by the new Nomasense technology.

This is a photo-optical system which reads an O2-sensing dot glued to the inside of a bottle and capable of reading the O2 inside without opening the bottle.

We simply fill with a bulk wine sample, newly made or ready to bottle, and place in an argon atmosphere at constant temperature and read the dissolved oxygen (D.O.) over time.

It turns out that fragile whites consume around 0.1 mg/L per day, which young, robust reds will take up as much as 1.0 ppm per hour – a thousand times the reactivity! This information is critical to informed decisions about shelf life, reduction potential, proneness to oxidation, closure choice, blending options, barrel time, release dates, and even ripeness feedback.

The analysis is in the ISO certification process now and being beta-tested to determine what the slopes mean for various varieties. We are recruiting interested beta-test partners now.