You have reached the fourth part of our series on organic and biodynamic wine, and now we dive into one of the most misunderstood topics of all: sulphur. If you have heard that sulphur causes headaches, that natural wine is always sulphur-free, or that "no added sulphur" is the same as "without sulphur", then you are in good company. The reality is a little more nuanced, and fortunately also more interesting.
Sulphur, or more precisely sulphur dioxide (SO2), has accompanied wine for centuries. As early as the late 1400s, winemakers began burning sulphur-rich wicks in the barrels before filling them with wine, because it made the wine more stable. Let us look at what sulphur actually does, and what it means for you when you stand with a bottle in your hand.
Hvad du lærer
- Why sulphur is used in wine production, and what it protects against
- The difference between sulphur that is added and sulphur that forms naturally
- What the term "no added sulphur" actually entails
- How to approach sulphur in practice when you choose wine
Why sulphur is used
Sulphur dioxide solves two fundamental problems in wine. It acts both as an antioxidant and as protection against unwanted microorganisms.
As an antioxidant, sulphur protects the wine against oxygen. When wine meets oxygen in an uncontrolled way, it can oxidise: fresh fruit aromas fade, white wines turn golden and eventually brownish, and the wine loses its freshness. Sulphur captures some of the oxygen compounds that would otherwise set this process in motion, and thereby keeps the wine fresh and lively for longer.
As microbial protection, sulphur keeps certain bacteria and wild yeast in check. This is especially useful early in the process, where you want to control what happens in the must, and later before bottling, where a small addition helps the wine stay stable in the bottle. A little sulphur added before bottling thus provides both protection against oxygen and against unwanted microbial activity at once.
It is worth noting that sulphur works better in wines with low pH, that is, wines with good, fresh acidity. The acidity simply reinforces the effect of the sulphur, so well-acidified wine often needs less sulphur to be stable.
Added vs. naturally formed
Here it becomes important to distinguish, because this is the source of some of the confusion.
When the yeast converts grape sugar into alcohol, small amounts of sulphur are formed quite naturally as a by-product. This happens in virtually all wine, regardless of how it is made. That is why there really is no wine entirely without sulphur. Even a wine where the producer has not added so much as a gram will contain a small amount of naturally formed sulphur from the fermentation itself.
What the winemaker can control is the added amount. Sulphur is typically added at a couple of points: at the pressing or crushing of the grapes, and again before bottling. The amount depends on how healthy the grapes are, what type of wine is being made, and how long it should be able to keep. A fresh white wine meant to be drunk young and a powerful red wine for long ageing are not necessarily treated the same.
When some of the sulphur is added, it binds quickly to other substances in the wine, while the rest remains "free" and still active as protection. It is the free part that does the actual work against oxygen.
Where does bad smell come from?
You may have experienced a smell of boiled eggs or a sulphurous whiff in a glass of wine. As a rule this is not caused by the sulphur dioxide itself, but by other sulphur compounds that can arise along the way, for example if sulphur has been used incorrectly in the vineyard against powdery mildew. In small amounts, certain sulphur compounds can actually contribute positively to the aroma, while too much detracts from it. So it is not sulphur itself that smells of eggs.
Wines without added sulphur
As interest in natural wine and low-intervention wine has grown (which we covered in our article on natural wine), wines "without added sulphur" have become more widespread. The term means exactly what it says: the producer has not added sulphur, neither during the process nor before bottling. It does not, however, mean that the wine is entirely free of sulphur, since the small naturally formed amount from the fermentation is still there.
Leaving out added sulphur places greater demands on the whole process. Without the extra protection against oxygen and microbes, the grapes must be healthy, the hygiene in the cellar impeccable, and the handling careful. Many of these wines therefore have a slightly different expression: they can seem more "alive" and can vary more from bottle to bottle. Some love precisely that unpredictability, others prefer the stability that a small sulphur addition provides.
Nor is it an either-or. Many skilled producers, not least within organic and biodynamic wine, work deliberately with as little added sulphur as possible without doing entirely without it. The idea is to let the wine express its origin while it remains stable.
What it means for you
So what can you do with all of this in practice?
First: sulphur is not an enemy, and low levels are quite common in good wine. A well-balanced addition helps the wine taste fresh and keep as the producer intends.
Second: if you want to try wines with little or no added sulphur, remember that they are often more sensitive. Store them cool and dark, and consider drinking them while they are young and fresh. Some also benefit from a little air in the glass.
Third: do not go looking for a particular label if you simply want to drink well. Sulphur is one parameter among many. Taste, origin and growing method often matter more for your experience. The best wine is still the one you yourself enjoy, with the food you love.
Kort fortalt
- Sulphur (SO2) is used in wine as an antioxidant and as protection against unwanted microorganisms.
- A small amount of sulphur is always formed naturally during fermentation, so a completely sulphur-free wine really does not exist.
- "No added sulphur" means that the producer has not added sulphur, not that the wine is entirely free of it.
- Sulphur works more strongly in wines with low pH and good acidity, and a well-judged amount helps the wine stay fresh.
- Wines with little or no added sulphur can be more sensitive and should be stored cool and preferably drunk young.
Ofte stillede spørgsmål
Does sulphur in wine cause headaches?
It is a widespread assumption, but the connection is not clear-cut. The amount of sulphur in wine is small, and many other factors, such as the amount of alcohol and how much you drink, play a part. If you are curious, you can experiment and notice how your body reacts to different wines.
Is organic wine always low in sulphur?
Not necessarily, but organic and biodynamic producers often work deliberately to keep the addition low. Healthy grapes and careful work in the vineyard and cellar make it easier to manage with less sulphur.
Klar til næste skridt?
Now you have a handle on what sulphur does, and why it need not frighten you. In the next part we look further out into the vineyard and see how the growing itself can help make the wine healthier and more sustainable. Read along in Sustainability in the vineyard.
If you feel like tasting your way forward, you are welcome to explore our selection of organic and biodynamic wines. And remember: the best pairing is still the wine you like, with the food you fancy.