Sunday, February 15, 2009

Can't hold the sulphites?

There are a lot of misconceptions surrounding organics and wine, and especially about the role of sulphites in organic wine. But why are they there? Are they dangerous? If so, for whom? And if they are necessary, then what are acceptable levels?

Sulphites refer to the family of sulphur-based compounds - those most commonly used in winemaking being the gas, sulphur dioxide (SO2), and the powder, potassium metabisulphite. Sulphites are naturally produced by many organisms and found in such food items as grapes, oranges and chicken eggs. They are even produced by our own bodies, close to a gram per day.

Because of their antioxidant and antimicrobial properties, they are used as preservatives for a number of foods, including dried fruit, shrimp, fruit juice, potato chips and a variety of fresh vegetables. Ultimately, they keep our foods fresh-looking and give them a longer shelf life. And wine is no different.

How sulphites get in your wine

All wines contain sulphites. They are a naturally occurring by-product of the fermentation of grape sugars by yeasts. The amount is minimal, generally under 10 mg/L, but that means a sulphite-free wine does not exist. But adding extra sulphite has become an accepted and, for most, a necessary part of modern winemaking's battle against the two enemies of wine: bacteria and excessive oxygen.

They are used to clean winemaking equipment, like barrels, which assures that spoilage bacteria like brettanomyces do not become a problem in the winery. They are added directly to the uncrushed grapes as they come in from the field, which helps prevent unwanted wild yeast strains and other bacteria from taking control.

During fermentation, some winemakers will add sulphur to protect the future wine from contact with oxygen. Because it is a yeast killer, it is sometimes added to stop a fermentation if the winemaker wants to leave some residual sugar in the wine, as with German Rieslings. Perhaps the most significant addition happens at bottling, where a final dose of SO2 is added to protect the wines while they are being shipped around the world. Even more importantly for wines that are to be cellared, sulphite additions are used to prevent oxidation, assuring that the wines will reward those who stash their bottles away.

Free and combined

One of the peculiarities of sulphites is that they are constantly being ingested by the wine, reacting with oxygen and other chemical elements. These are referred to as "combined" sulphites. Once ingested, they have little or no preservative effect on the wine.

Free sulphites are the uncombined sulphur compounds that remain in the wine and protect it from oxidation and other potential problems, such as an unwanted fermentation that can result from the combination of having live yeasts and residual sugars in the wine, and storing the wine at too high a temperature (above 14C).

I remember a case of vouvray I bought a couple of years back that had no added SO2. When I bought it, it was demi-sec, meaning that it had some residual sugar in it. During the winter, when my cellar temperature hovers around 10C, the bottles were fantastic. But as summer arrived and the temperature rose in my cellar, because the wines still contained live yeasts, my wine started fermenting. The result? My slightly sweet white transformed itself into a dry bubbly. It was still okay, but not what I paid for.

Sulphites and your health

I spent the better part of a week looking at whom, in fact, the "contains sulphites" warning is for. Not very many of us, apparently. Studies seem to point to two groups: people who suffer from sulphite oxidase deficiency (under one per cent of the population) and asthmatics. In the case of asthmatics, reactions only seem to occur when sulphites are near the maximum allowable levels (over 300 mg/L). There is little evidence that they are bad for the rest of us.

What about the classic "red wine headache" after an evening of revelry? Sulphites are usually blamed, but red wines usually have the least amount of sulphites, because they already contain natural antioxidants that come from the skins and the branches of the grapes. White wines and rosés, which aren't macerated with the grape skins, require more. Sweet wines have the most, because the SO2 combines so readily with the sugar. It seems that headache comes from other elements of a red wine - perhaps histamines.

In the European Union, the maximum sulphite level for red wine is 160 mg/L. The limit for whites and rosés is 210 mg/L, and for sweet wines it's 400 mg/L. In the U.S. and Canada, the maximum level is set at 350 mg/L. While organic certification agencies are specific to grape growing, certain agencies (like the biodynamic certification agency Demeter) do impose limits on the maximum amount of sulphites allowed in wines made with biodynamic grapes, which is usually half of "conventional wines."

When I asked the SAQ laboratory about its policy on sulphite levels, the response was that while they check to assure a wine is under the maximum allowable levels, they don't have a specific amount that they want to see in a wine. If they judge it necessary, however, they will ask winemakers to increase sulphite levels. Their primary concern, like most retailers, is shelf life. This means that many of our wines probably contain more sulphites than necessary. I have talked with a couple of organic winemakers who add extra SO2 to satisfy their export markets, even though they feel their wine doesn't need it.

So why hold the sulphites?

If the health issue is not very important, why even be concerned about sulphite levels? My concern is a qualitative issue. Sulphur dioxide smells like a freshly struck match. Studies show that most people can detect the odour at over 40 mg/L, though some sensitive noses can detect it at lesser levels.

Marcel Lapierre, Beaujolais winemaker and one of the gurus of "natural winemaking" (wines without added sulphur), told me that sulphur alters the aromatics of his wine. I would concur. I drink lots of these wines, and they have a purity of fruit in their bouquet that one does not find in more conventionally made wines. I know many wine makers who only add at bottling as they believe that earlier sulphite additions have a negative effect on the fermentation process, again , especially for the aromatics.

On the other hand, I have had a number of these wines that went the route of my vouvray. While certain winemakers have theories as to how to almost completely reduce the need for sulphites, I am happy with those who try to use the minimum.

Back to being bitter about modern wines next article.

1 comment:

firstpress said...

Love this. Keep it going.

What if a wine maker oxidises before ferment? Does he then get to use less sulphur afterwards? Also does soil type play a part in sulphur levels?