Sulphur in Wine

Sulphur may receive a bad press, but it remains an additive integral to sound winemaking. Tim James gives it a fair hearing. There are a few quirky aspects of the new regulations requiring wine labels to warn drinkers that sulphur is present. First, they unexpectedly abandon standard South African English by prescribing a declaration that the wine contains "sulfites" -- although slightly abashed authorities, on being questioned, assured me that an "h" spelling will be permitted. The second oddity is more fundamental: why must wine carry the warning, when other food and beverage products preserved with more sulphites (dried fruit, for example) don't need to?

 

The vast majority of us - those without severe asthma, and with no allergy or intolerance to sulphur dioxide - should find it more reassuring than otherwise that a wine contains sulphites, especially if we prefer our wines to stay fresh for more than a few months and don't like it to collapse brownly the moment the stopper is drawn (or unscrewed).

Certainly, virtually every South African wine must confess to containing this particular additive. So too must those of the rest of the world, including the USA and Australia, the only other countries requiring such label alerts.

The remarkable properties of sulphur dioxide have been recognised and exploited for millennia - at least since the Romans used sulphur to fumigate wine storage vessels. Five centuries ago, a Prussian royal decree officially recognised its value in winemaking. Later, barrels in Bordeaux were routinely sterilised by having sulphur candles burned in them. By the 20th century the use of sulphur dioxide came to pervade all stages of making and maturing wine across the winemaking world.

Quite an achievement for a substance widely associated for a long time with the realms of Beelzebub. Why has it become an indispensable adjunct to modern winemaking? Sulphur dioxide plays two roles: first, it is an anti-microbial agent, usefully knocking on the head numerous fault-producing yeasts and bacteria, while allowing the desirable types to perform their fermenting labours. As such, judicious doses are applied at many stages of the winemaking process: from fermentation all the way through to bottling.

Secondly, sulphur dioxide is an anti-oxidant, a powerful force in preserving wine's freshness, particularly through combining with oxidising agents encouraged by the presence of oxygen.

Furthermore, its murderous tendencies are again useful when it comes to dealing with those fruit enzymes that lead to browning. Fresh, fruity wines, particularly white ones, rely heavily on sulphur. Public disquiet and a more complete understanding of sulphur's nature and effect mean, however, that careful winemakers are reducing its use to a minimum - although doubters suspect that some modern styles of fruit-driven wines require more sulphur than ever. Either way, at some level sulphur seems to be here to stay.

Why the concern? Intelligent use of sulphur dioxide seems unquestionably beneficial to wine. Excessive, incompetent use can, of course, hinder winemaking (stopping a healthy fermentation, or blocking the malolactic fermentation, for example). Present in excess, it can add an unpleasant detectable smell and even taste. Some European wines have been spoilt in this way in the past - with those of Germany, Sauternes and Chablis most often accused. It should be noted, though, that the rotten-egg smell sometimes called "sulphurous" is actually hydrogen sulphide, and a fault not related to levels of sulphur dioxide. For most people (and sensitivities vary), concentrations must exceed 200 milligrams per litre (mg/l) in white wines, and 100 in red wines to be at all detectable. Incidentally, South African regulations impose a basic upper limit of 160 mg/l, with higher levels allowed for sweeter wines.

General concern about the ever-increasing reliance on additives is undoubtedly justified, and awareness of ill-reputed sulphur prompts worry about its use. The real problem is that it can trigger headaches and a range of other responses in a tiny minority, even posing an acute danger to some asthmatics.

Mary Krone of the Twee Jonge Gezellen estate in Tulbagh finds it impossible to drink more than a small quantity of ordinary wine without her chest seizing up, but fortunately she has access to plenty of the estate's Krone Borealis Méthode Cap Classique, in which sulphur dioxide plays only a minute role. It's added to the still wine as the topping-up "dosage" before the cork is inserted. In fact, sparkling wines are able to get closer than still wines to a diminished-sulphur ideal, for reasons connected with the specific production processes involved and the preservative powers of all those carbon dioxide bubbles, as well as the normally higher acid content of the grapes.

Even when no additions at all are made, however, completely sulphur-free wine is impossible, as small quantities are naturally generated through the fermentation process. The new regulations recognise this, allowing wines with less than 10 mg/l to omit the warning.

There is undoubtedly a potential market for wine made without added sulphur. Allan Mullins of Woolworths gets half a dozen enquiries a week about it, for example. The store used to carry a small range of unsulphured wines until the difficulties involved - primarily the short shelf-life of such wines - became overwhelming.

But though Mullins would love to source and stock wines that don't need to carry the new warning about sulphites, sadly, they are few and far between. Even organic wines have minimal sulphur additions. At present the only unsulphured Cape wine commercially available seems to be another bubbly - Villiera's highly reputed Brut Natural Chardonnay Cap Classique. While needing more careful storage than conventional wines, it has proved more resilient than winemaker Jeff Grier expected, with the maiden 1998 still drinking well. Given Villiera's aim for more naturalness, Grier would relish making also still wines without sulphur. That goal remains elusive, however, and he must be content with using the least he can get away with. "If you can manage to make as good a wine with less sulphur," he believes, "it is generally a better wine than it would have been otherwise." For it is likely that sulphur destroys beneficial yeasts and bacteria alongside the harmful.

With better winemaking techniques available, and with healthier grapes coming from better-managed vineyards, reductions in the frequency and scale of sulphur dioxide additions are becoming easier.

Meanwhile, if experience elsewhere is anything to go by, producers should ready themselves for complaints from customers who notice the new label warnings about sulphites. After similar warnings were introduced in the US and Australia, drinkers demanded that winemakers stop using this nasty modern additive. They were convinced the wine tasted different, and were unwilling to believe that all that was new was the text on the label.