A guide to sulphites in wine Sulphites in wine are one of the most discussed and misunderstood topics in the wine world. If you’ve ever looked at a bottle label and seen the phrase “contains sulphites” you might have wondered what it means. It may even have put you off buying the bottle as the word sulphites (or sulfites) does not sound very wholesome. But the majority or wines, even so-called natural wines and certified organic wines may contain these compounds. The questions that people ask me most frequently to try to understand what is in their wine include Are sulphites in wine harmful? Do they cause headaches? Why are they added to wine? In this guide, we’ll look at what sulphites are, why they’re used in winemaking, how much is usually found in different types of wine and whether you should be worried. And finally whether these much-aligned compounds do in fact cause headaches. By separating the fact from the fiction, you will understand sulphites in wine better and be in a position to make more informed choices about wine. WHAT ARE SULPHITES? In wine sulphites are effectively sulphur dioxide (E220). Sulphur dioxide is in fact a natural by-product of the fermentation process although it is produced naturally in very small amounts. In addition sulphur dioxide in the form of liquified gas can be added to wine.   Potassium metabisulphite (E224) and potassium bisulphite (E228) can be added as alternatives since they release sulphur dioxide when added to an acidic aqueous liquid like wine or grape must. WHY ARE SULPHITES IN WINE? As mentioned above, sulphur dioxide is produced naturally in the wine-making process from yeasts during fermentation. In fact it can be said therefore that no wine is completely free from sulphites.  A range of 10 to 40 PPM is considered ‘normal’ i.e. a wine with up to 40 PPM is likely to have or considered to have only naturally occurring sulphur.  It is important to note that if no supplementary sulphites are mixed into the wine, those wines can be labelled with “No sulphites added”. This term seems to be used more and more frequently as many quality wine producers try to keep intervention in the wine-making process as minimal as possible. There are several reasons why additional sulphur dioxide may be added: as a preservative to stop oxidation or repair oxidation damage and thus conserve fruit flavours and aromas to kill bacteria and microbes to prevent or delay malolactic fermentation (more on that subject coming in a later blogpost). And it may be added at different stages of the winemaking process: in the vineyard when the grapes arrive at the winery as they are then very vulnerable to oxidation and infection after primary fermentation at bottling. SAFE LEVELS OF SULPHITES IN WINE It is as a result of the EU and UK food allergens labelling regulations that those words of warning “Contains Sulphites” (as shown on the left) are required on the label of wines if they contain more than 10 parts per million (“PPM”) of sulphites in the finished product that is ready for consumption. This figure is equivalent to 10 mg per litre or 10mg per kilogram, so a very small amount. The level of sulphites in wine range can range from about 10 PPM to c.400 PPM.  It may surprise you to know that white wines generally have more sulphites than red wine. This is because white wines are more susceptible to oxidation, not having the high levels of natural antioxidants that red wines have. Another general rule is that the sweeter the wine, the higher the level of sulphites is likely to be in order to ensure no further fermentation of any residual sweetness. MAXIMUM SULPHITES PERMITTED IN WINE Nevertheless the EU sets limits for different styles of wine and these have reduced over the years. As a rough guide here are the EU / UK maximum permitted levels for different types of wine: dry red wine                          150 PPM organic dry red wine               100 PPM dry white & rosé wine              200 PPM organic dry white & rosé wine   150 PPM sparkling wines                      185 PPM sweet wines                          300 – 400 PPM depending on level of sweetness   It is important to note that biodynamic and organic wines have lower maximum limits and that some of the biodynamic and organic associations have their own stricter levels so on the whole organic wines have some notable benefits.   Note also that the US sticks to a maximum of 350 PPM for all wine. SULPHITES IN WINE VS SULPHITES IN FOOD Wine is often perceived as one of the worst culprits for high levels of sulphites. But let’s put things into perspective. Many ‘ordinary’ foodstuffs contain higher levels than most wine. Many dried fruits for example can be especially high in sulphites at up to c.3000 PPM so in comparison 400 maximum PPM for the sweetest wines does not seem particularly high. Foods that fall into the same ‘high sulphite’ category as wine include fruit squash, fruit juices, condiments including some mustards, bottled lemon and lime juice, pickled foods and vinegar, jam, tinned coconut milk, soy sauce and processed meats products.  REDUCING SULPHITES IN WINE The good news is that the permitted levels are much lower than they used to be so winemakers have to control contact with oxygen much more tightly and should therefore use sulphur dioxide sparingly. Much research has been done into replacing sulphur dioxide in the winemaking process but there is no one substance that could perform all its functions. So even if heat treatment for example is used to eliminate microbes, sulphites may still be added to prevent oxidation. And the heat treatment can