Sulphur dioxide (SO2 or sulfites) preserves wine from bacterial infection (turning to vinegar) and acts as an antioxidant, which keeps the wine from turning to a brown color. Without sulfites wine can easily spoil.
Whilst EU organic standards limit the amount of sulfites which can be added to organic wines to about one third less than the amount which is permitted to be added to conventional wines, Sulfites are, nevertheless, added to just about all organic wines. For most wines (dryish whites and reds) the organic maximum is 140mg per litre. For sweeter organic wines up to 320mg/l is permitted. Although these are the maximum limits, unfortunately, there is no real way (without sending it away for analysis!) of knowing just how much sulfite there is in any particular bottle of wine.
Very small amounts of sulphur dioxide are created by the fermentation process itself, so you will not find any wines totally free of sulfites. There are however, some wineries who are experimenting with creating wines without the addition of any sulphur dioxide, the so called "no sulfite added" wines or 'orange wines'. Probably the reason so few wineries are attempting to create wines without any added sulphur dioxide is perseved lower quality of the resulting wines and because of the high-tech equipment, and high capital cost of such equipment. In addition, the grapes would need to be entirely free of Botrytis (grey mould), as it is sulphur dioxide which is used to suppress the oxidation caused by botrytis. Furthermore, low sulphite wines have to be drunk young and probably the whole bottle in one sitting, as it will not be at it's best the following day once the air has got to it. "Many so called 'natural' wines are a little "funky" and an acquired taste. Many have consistency problems, not just between different vintages but even from bottle to bottle of the same batch. Whites tend to be at least slightly oxidised and either dark yellow or orange in colour - the producers may tell you this is intentional but it usually is not! It is because of a chemical relationship between the natural acidity of a wine and the low sulphite content! It is physically impossible to have a wine with good acidity without at least some sulfites in there" (http://www.goodwineonline.co.uk/acatalog/Sulphite_Free_Wine.html).
If you wished to try some of our Sedlescombe Organic/Biodynamic wines then the ones with the lowest sulfite levels are the Sparkling Wines because the bubbles in sparkling wine help to keep the wine fresh and prevent oxidation. In addition, the grapes used to make sparkling wines have to be free of botrytis, as the bottle fermentation could be adversely affected if large amounts of sulfite were required to 'fix' the botrytis.
Sedlescombe 2014 Premier Brut white sparkling for example, has only 8mg/l Free and 61mg/l Total SO2 and the 2013 Rosé Brut only 2g/l Free and 19mg/l Total. Contrast this with our 2016 sweet dessert wine which has 32mg/l Free and 307mg/l Total
Other Sedlescombe Whites have just over 20mg/l Free and between 73mg/l and 119mg/l Total, whereas Sedlescombe 2015 Regent-Rondo Red has 13mg/l Free and 42mg/l Total SO2.
My own personal view (based solely on mine and my wife Irma's experience) is that the allergic reactions which some people attribute to sulphur-dioxide could perhaps have their cause in the chemical disease control sprays used on vines in conventional vineyards. These are invariably 'systemic' meaning they enter the sap system of the plants and have been shown to be present, albeit in very small quantities, in very many non-organic wines.
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