Sulfites in Wine

Hello, bonjour, and welcome to your New Bonner Private Wines video. Today I want to clarify for you a point I'm sure a few of you have been wondering about. What are sulfites in wine and why are they used in the first place in our vino? 

You would have heard that there is this additive that is used in wine making called sulfite or sulfites, or you would have seen the mentioned contains sulfites on wine labels and wondered perhaps what this is for.

There are quite a few myths and misconceptions about it, and it's actually fairly simple to explain what's going on here and to debunk some fairy tales about it. So let's have a look into this. 

What Are Sulfites in Wine?

What is commonly called sulfites is, without going too deep into the chemistry at all, it's actually pretty simple. It's a molecule called sulfur dioxide or so2, one atom of sulfur bound to two atoms of oxygen, just like carbon dioxide is one atom of carbon with two atoms of oxygen.

Essentially, this is a compound that is very easy to produce and rather natural. You take some sulfur, you know, this yellow mineral that you found around volcanoes that smells like rotten eggs. You take the sulfur and you burn it. It literally burns like a piece of wood, wood. And that forms a gas that's called sulfur dioxide or SO2.

Just like if you burn wood, it makes SO2. You can dissolve these gas in water to make a solution. And add a little bit of that into wine. Or you can burn a little ring of sulfur, this yellow compound directly inside a wine barrel and then filled the barrel with wine. And so my SO2 will naturally dissolve in the liquid.

So it's simple and fairly natural a process to make and to use SO2, and that's exactly why it's been used for centuries, because you just burn that little piece of sulfur and that's it. You don't need any advanced chemistry or anything of that sort. It's actually commonly formed in nature. Sulfur dioxide is not only used in wine, there's some in the fruit juices that you drink in the morning, your orange juice, for example, and there's some dried fruits like raisins and dates in particular, but also other types of food products.

Because it's cheap and easy to use. There's even naturally small quantities of sulfur dioxide that are present in wine, even if you don't add any to it. The yeasts that ferment the wine during the fermentation and the winemaking process, those yeast produce a little bit of it naturally. That's why there's no no sulfite wines. It doesn't exist.

There's always a little bit of it because it's what happens when you have some sulfur which is present everywhere in nature and in organisms in particular, and you have some oxygen that is also present everywhere. It makes naturally and then a bit of SO2, this sulfur everywhere. If you don't know, that's what makes eggs smell funny or cabbages or anything that's rotten in smells a bit funny because of the sulfur.

And it's one of those minerals that are very common in nature and present in living plants and animals, and it actually useful to them, to us, like nitrogen, potassium, phosphorus, etc. Sulfur dioxide is just a specific form of sulfur, but one that is also present in nature. 

But what does this SO2 do in wine? 

What Are Sulfites For?

Sulfur dioxide has two properties in particular that justify US winemakers adding it to the vino and other fruit juices.

First, it's antioxidant. It binds with the oxygen so the oxygen can't oxidize. All the things in the juice, all the wine it captures if you wish, that oxygen. So it's not available for other things to be oxidized. That's part of why when you leave a bottle of wine open in your fridge or outside for a while, it doesn't spoil that quickly because SO2 protects it a little thanks to its antioxidant effect. 

Now, to be perfectly clear, it's not an antioxidant as tannins are when you have it, the SO2, in your body, doesn't protect you like tannins do, but it does protect the wine. Secondly, on top of capturing the oxygen in the wine, SO2 has an antiseptic effect, bacteria in particular, and to a lesser extent yeasts don't like it.

They don't grow well when this SO2 around them, even regardless of the antioxidant effect, they just don't like it. So it protects the wine because bad bacterias like the ones that turn wine into vinegar, can't grow as fast in a wine that has SO2. Then if there were. And so too. And that's because they have less oxygen available, but also because SO2 has these antiseptic properties.

Those two properties are very useful in winemaking because winemaking is essentially turning grape juice into wine and preventing it from turning into vinegar, which is the natural fate of grape juice. We want to stop this natural evolution right where it's convenient for us, where we like it, at the wine state before it continues to grow naturally towards the vinegar state.

Well, SO2 just does exactly this. Yeasts don't mind it too much so they can still ferment the juice to turn it into wine, which we love. But bacteria don't like it so they can spoil the wine into becoming vinegar. Simple, right? 

So for the bright side of sulfites in wine, I'd say sulfur dioxide is pretty much the most natural molecule that you can find that protects your wine in such a way.

And that's precisely why we've been using it for centuries. You don't need elaborate chemicals, you don't need antibiotics or whatever, just SO2. But of course, the fact that it's been used for a long time doesn't mean it's good for you. Famously, the ancient Romans added, lead to their wines, and that might have played a part in the demise or of their civilization.

Right? You would have heard that story. But that's another story. Let's look into whether or not sulfites are bad for you or not. 

Are Sulfites Bad?

As we've seen, sulfites are naturally present in nature, in what we eat or drink, so our bodies know it and they deal with it on a daily basis. Our bodies process it even if it's not useful, let's be clear to our nutrition, it's not something completely foreign to it either, of course, because we've added some to the wine is more in it than what would naturally be present. So it's not ideal, but the levels, the concentration that are used in wine which are regulated and controlled, make them way below the maximum recommended daily intake.

So you'd have to drink maybe three or four entire bottles of wine to reach the maximum recommended amount that you shouldn't be ingesting because it's not a poison, just something not great, but fairly inoffensive that normally our body can deal with easily. It's not actually very bad. That's it. Some people, especially people with some heavy asthma, can be very sensitive to it as it can activate and cause asthma problems.

So that's something to know. I think it's about five or 10% of people with asthma are very sensitive. So that's something really to have in mind. At some point, sulfites were pointed at for causing headaches, although since medical research has not yet certainly established the relationship between sulfites and headaches. But all the compounds such as histamines that are involved in allergies, the tannins and of course the alcohol itself are more likely connected to the unfortunate headache effect of wine that we know.

For pregnant women, sulfites are not the primary reason why wine can be harmful. The alcohol contained in the wine is, of course, so it's not entirely all white or all black, as nothing is when it comes to health and nutrition. But overall, sulfites in wine aren't considered a very bad thing. A small inconvenience. It is that we have to live with as part of enjoying wine, yet sulfites to affect the aroma and taste of our wine.

You can't necessarily taste it for itself, but it affects the overall flavors and aromas of the wine. So wines with a lot of SO2 are not very enjoyable, and even a small level of sulfites do modify the way your wine smells and taste. 


And that last point that I made leads us to answering a common question about sulfites, and I'll finish on this.

Does every wine contain sulfites? Virtually every wine, I'm afraid, does contain some sulfites, indeed, because it's pretty much part of the recipe for the elaboration of most wines. If we want them to be nice and clean and actually taste good, like food, like something pleasant. Right. Not vinegar, although as a general rule, the sweeter the wine, the more sulfites it's going to contain because it needs more protection against bacteria who love sweet wines.

They're not sugar like we do. So you have to protect them with more sulfites. If you don't like sulfites, avoid the sweet or very sweet wines. So even sweeter wines, the sweeter rosé, for example, is likely to have a bit more sulfites. And then there is this fairly new trend called natural wines that have become more and more common, right?

Some often small producers choose not to use any sulfites or any additive. Add that and let the wine be what it's going to be. Those can sometimes be very good, but not always, and they are more fragile wines that you generally have to drink rather quickly or avoid any sort of heat or even room temperature. They won't last very long.

They are very delicate wines. Some producers now make no added sulfites, wine using more modern approaches, using some specific tannins that they add that protect the wines, are introducing some good bacteria into the grape juice to protected when those are crafted well and precisely with modern techniques, those control sulfite free or no added sulfite wines can taste actually extremely good because you get the unspoiled grape juice or wine flavor without the interference from SO2.

If you've never tried it, SO2 free or no added sulfites, wine are definitely recommended. There's not many of these around, but they exist. And more and more. And I do recommend tasting them. If you ever get a chance. Every time I come across one on a shelf at a shop, I do try it because you get that vibrancy of fruit and it's amazing.

On this little recommendation, I hope I’ve demystified a few things about sulfites. I'll leave it here for today. Thanks for watching and I will see you soon in the wonderful world of wine.

Bonner Private Wine Partnership