SO2 in wine – does it make it like vinyl or autotune?

The use of SO2 in winemaking is a hot conversation topic among producers and industry professionals. There are those who champion its use freely, while others shun it almost entirely.

I got in touch with some leading voices in the natural wine movement in the US to get their thoughts.

What do sulphites do?

In addition to acting as a preservative for wine, sulphites also double as a sanitiser for fruit, as well as helping keep fermentations from going awry.

‘The benefit of using sulphites is that it cleans the fermentation environment, so one is more easily able to regulate fermentation to ensure no defects,’ explains Zev Rovine, owner of New York-based Zev Rovine Selections.

Patrick Cappiello of Monte Rio Cellars in Sonoma and a big natural wine advocate expands on this, stating that sulphites remove ‘distractions’ from the yeast, and help avoid stuck fermentations – as well as the developments of faults in wine (mousiness, brettanomyces, etc.).

Matt Crafton, winemaker at Napa Valley-based Château Montelena, adds that in addition to preventing oxidation and/or microbial spoilage, sulphites also create bottle to bottle consistency, giving assurance to regular customers.

Downsides to using sulphites

On the other hand, Rovine explains that the benefits of using sulphites can also be a curse.

‘The downside I think is that when you clean your fermentation environment, you sterilise the microbiology – good bacteria, yeast complexities – out of it, [sometimes] to the point that it’s no longer that expressive,’ he says.

Brent Mayeaux, winemaker at Stagiaire Wines – a fervent believer in no-sulphur winemaking – echoes this, stating that while using sulphites at the destemmer or press can provide an environment for strong yeast to flourish, it also creates much less microbially diverse ferments.

‘You might not have any spoilage, but with a whole swath of hundreds of thousands of yeasts working on that wine, you get a much more complex fermentation,’ he says.

When to use sulphites

Cappiello explains that the first opportunity to use sulphites during winemaking is when fruit comes into the winery.

‘If the fruit looks raisined or has some mildew buildup, then we set up a pump and add just 10 parts per million [ppm]; all that does is help the juice go from brown to the colour of wine,’ he says.

He likens it to using hydrogen peroxide on a wound – and in both cases, states that using too much can be counterproductive.

‘[Too much] can start to strip the wine; like anything not done in moderation, going overboard with it can compromise the integrity and structure of a wine,’ he says.

The next opportunity would be during pressing, where Cappiello explains that 10-15ppm can help wake up tired yeasts and aid in getting a fermentation fully dry, followed by doing so at barreling.

‘By adding 20ppm at barreling, you [create] a little blanket to keep the wine safe,’ he explains, saying that if a barrel has brett or a cracked bung stave, sulphites will protect the wine inside of it – and will likely dissipate out.

The last opportunity is during racking or at bottling, where it acts as a sanitiser and protector, even with as little as 10ppm.

Timing matters

Rovine finds that the moment at which one uses sulphites matters, particularly in the lens of terroir reflection.

‘If you’re using it during fermentation, you’re really altering the yeast complexity, and for me, yeast is a big part of the story of terroir,’ he says.

He believes that adding small amounts near the point of bottling has less of an impact on the final taste of a wine.

Though, on the zero-zero end of the spectrum, producers like Mayeaux find sulphites to be a crutch.

‘Using sulphites early on corrects bad fruit, and adding sulphites later in the process makes up for bad winemaking,’ he says.

Mayeaux finds that if one can get through fermentation with a clean and stable wine, that adding sulphites towards the end of the process can lock the wine down in a constraining way.

‘That being said, I also don’t like drinking bad wine, so as much as you can cover up and confiscate terroir with sulphites, you can also do so if you’re not careful [during the winemaking process],’ he says.

For Rovine, being more dogmatic about vineyard practices than sulphites is more important, especially in the context of climate extremes.

‘Let’s have an open heart for the fact that weather is crazy, and if you have mildew or are not able to do enough triage so you add [a small amount] of sulphites, I’m not going to [criticise] you, because it’s your job to make wine,’ he says.

Sulphite ‘sweet spot’ – how much is too much?

Crafton notes that as with many topics in wine, the question of whether to use sulphites or not isn’t binary, though there is such a thing as too much.

Rovine agrees, stating that the general standard for usage of sulphites in conventional wine is far too much, and that using it in large amounts drastically changes the taste of a wine.

‘I do believe that these wines are less terroir expressive than those done with very little or zero [sulphites],’ he says.

Crafton believes in using sulphites judiciously, and with good reason. For others, like Mayeaux, the best solution is no sulphites at all.

‘Brett and other [faults] can be managed with good vineyard and cellar practices, so for me, sulphite-free winemaking is the most interesting intellectually, because I really get to see what someone is doing in the vineyard and in the cellar,’ he says,

However, Cappiello notes that he previously tried to work with no sulphites, and quickly noticed that the wines were falling apart.

‘I was running into a lot of problems, and then I realised if I added some sulphites, I’d have a lot less,’ he says.

Vinyl versus autotune

Cappiello thinks it’s a shame that sulphite usage often gets lumped into ‘conventional vinification practices’.

‘If we want to represent terroir responsibly, one of the best tools a winemaker can use to showcase the vineyard itself is sulphites because you’re removing any potential mess ups,’ he says.

To him, adding minimal sulphites in wine production is like using a modern record player – it offers a more representative experience of the creation at hand.

‘You’re taking the same thing – be it vinyl or wine – and creating a much purer, clearer, and deeper experience with it,’ he says.

Mayeaux also uses a musical analogy, though in a completely different way.

‘Sulphites to me are like autotune in music. It makes up for a shortcoming somewhere,’ he says.

Rovine reiterates his above point – and perhaps sums it up best, stating that if a small amount of sulphites allows a bottling process to go well, or permits bottles to avoid bottle shock and side flavours, he prefers the addition of it.

‘I think there’s a big difference between zero and a little bit,’ he says. ‘I think it’s nice to sell the best tasting wine that we can, and I don’t simply accept deviations as the beauty of nature, since we can fix it.’

Related articles

• No sulphites added: The great debate
• Sulphites in wine: friend or foe?
• What does minimal intervention really mean?