Increasingly more people ask us if we stock sulphite free wine. Sulphites are sulphur based chemicals which occur naturally during fermentation, as well as being added to wine as a preservative, disinfectant or antioxidant. The sulphites created during fermentation don't generally cause an allergic reaction, but those which are added by the winemaker can be a problem for people with a sulphite intolerance.
So, what's the problem with sulphites? Once ingested, people with a sensitivity to these chemicals can suffer from headaches, rashes, hot flushes, tightening of the skin, sickness or diarrhoea. If you suffer from asthma you may experience shortness of breath or feel tight chested and find it hard to breathe as a consequence of a sulphite intolerance. In the worst cases, people with a severe allergy to sulphites may even suffer from anaphylactic shock.
So why add them in the first place? They're often used to clean and disinfect the grapes once they've arrived at the winery and prior to the wine making process. Sometimes they have a role in killing off yeast and unwanted bacteria and they're almost always used as a preservative in cheaper wines which are usually mass produced and made from poor quality fruit.
Oxygen is a big problem for the winemaker. If there's too much oxygen left in the finished wine it will gradually oxidise it, making it 'go off'. To slow down this process they add sulphur dioxide - the sulphur dioxide molecules bind with the oxygen molecules in the wine, essentially blocking the agent which allows the wine to oxidise thus extending its life in the bottle. However, if too much is added it's easy to see that there will be a surplus of ‘free’ sulphur dioxide molecules floating around in the wine looking for oxygen to react with.
These ‘free’ molecules are the ones which can cause issues for people with an intolerance to sulphites. When they drink their wine the free sulphites seek to react with oxygen molecules in their bodies, and it's believed that this stimulates the production of histamines, which in turn starts the allergic reaction.
There's a compromise to be made, as without the addition of sulphites many wines would be ruined before leaving the winery, but a wine with too high a sulphite content can produce really unpleasant side effects in the drinker.
Sulphites occur naturally in wine at between 10 and 40 Parts Per Million (PPM). When more are added during the production process, total sulphite levels can reach 350 PPM. This is still less than the levels found in packet soups, french fries and dried fruit, but at these levels people with an intolerance would definitely feel some ill effects. It's accepted wisdom that someone who has a severe allergy could drink wine with a sulphite content of up to 35 PPM, and our Low Sulphite Wines use this yardstick as the upper limit in order to qualify for inclusion in our 'Low Sulphite Wine List'.