The use of sulphites is possibly the issue in the world of wine that I get asked about most. There seems to be an awful lot of myths surrounding it so the next couple of blogs aim to offer the facts and dispel some myths.
Why use sulphites in wine?
There are many uses for sulphites in winemaking covering all processes from picking to bottling.
When grapes are picked they are covered in a 'bloom' of wild yeast. There are millions of yeasts in the air and the winemaker has no way of knowing which yeast has attached itself to his vines. Fermenting with wild yeast can give unwanted flavours to the finished wine so most winemakers will use cultured yeasts so they know exactly what flavour they will end up with. When the grapes are picked they are sprinkled with sulphites which kills the yeast and prevents the grapes from fermenting prematurely.
Sulphur has great cleansing properties and has been used for centuries as a cleaning agent. If the picked grapes have small amounts of rot or mould the sprinkling of sulphur will clear it up. If there are any nicks or splits in the grapes' skin the sulphur will prevent any rot getting in. In the winery sulphur is used to clean out tanks and pipes and then rinsed away with water.
Once grapes are picked and exposed to oxygen they will begin to discolour. Think about when you chop an apple and how quickly the flesh turns brown, the same thing will happen to grapes and their juice if not treated with sulphur. It is a bacterial reaction to oxygen that causes the discolouration and sulphur prevents this from happening by acting as a preservative. For this reason you tend to find white wine contains more sulphur than red as we want our whites to look fresh and light and crisp, not brown and dull.
This is not to say that red wines do not contain sulphites, they do, just often to a lesser extent but having them present is what can help them age for years. They are essentially a preservative and in cheaper red wines they are used as a 'fixing' agent to keep the colour looking fresh and vibrant for longer.
Biodynamic and Organic wine
Many wine drinkers believe that if they drink biodynamic or organic wine they will avoid consuming sulphites. This is not true. Organic wines may be produced using grapes that have grown organically but once the grapes are picked they are treated like any others. And let's not forget that sulphur is a naturally occurring substance so many biodynamic and natural winemakers use it because it has been used for centuries and is, by definition, natural. You will find that these wines will tend to have lower quantities of sulphites in the wine as they believe in a minimal approach to winemaking.
How much is allowed?
If a wine is to be sold in the E.U. there is a threshold above which winemakers must state on the label that the wine 'contains sulphites'. This threshold is merely 10mg/litre of wine. The maximum amount allowed in white wine is 210mg/litre. The consumer then, has no idea if the wine they are drinking contains 11 or 210 mg/litre so my advice would be to go on cost. You will generally find that cheaper, more commercial wines, red and white, will contain more sulphites than more expensive, better quality wines. The reason being that the dearer wines are made using higher quality grapes, with more care and attention taken in the vineyard and winery so the need for sulphites is lessened. Sweet wines are allowed higher quantities because the presence of high sugar levels means there is more chance of them re-fermenting if they come into contact with wild yeasts, the sulphites therefore prevent this from happening.
Demeter is an organisation in France which certifies biodynamic status for wineries. The figures below compare the E.U. allowance with the Demeter allowance of sulphites in wine.
|Type of wine
|White / rose
Another thing to bear in mind though is that sulphites are a natural by-product of the fermentation process so even wines that have been produced without addition of sulphites will still have some present. No wine is truly sulphite free.
So that's the facts about the use of sulphites, in the next post I'll go over some FAQ's and maybe dispel a few myths.