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sulphurous acid

acide sulfureux (F)
acidità solforosa (I)
sulfurous acid (GB)
ácido sulfuroso (PO)
diwaterstofsulfiet (N)

Medium strength acid formed when sulphur dioxide is introduced into water; according to international standards it is called dihydrogen sulphite. Especially in warm environments, it has the tendency to change into the much more toxic and stronger sulphuric acid by oxidation. The salts and esters of the sulphurous acid are called Sulphites or also neutral or secondary sulphites, as well as hydrogen sulphites or formerly bisulphites or also primary or acid sulphites. When sulphur dioxide is added to mash, must or wine, most of it is converted into sulphurous acid, only a small part remains as sulphur dioxide. The sulphurous acid immediately begins to split into sulphites and hydrogen sulphites. Both enter into compounds with different substances in the wine. Only when these processes are complete is the so-called free sulphurous acid present. The amount depends on the temperature and the pH value, but is usually about 20%. This means that the major part of the sulphurous acid, around 80%, is present in wine in bound form.

The undissociated (unaltered) sulphurous acid or sulphur dioxide have antimicrobial effects, especially against acetobacter (acetic acid bacteria), lactic acid bacteria and wild yeasts. The hydrogen sulphites bind aroma-impairing substances, including acetaldehyde (alcohol precursor). The sulphites react with the dissolved oxygen to form sulphates and have a reducing effect. The sum of free and bound sulphur dioxide (sulphurous acid) gives the total sulphur (also total sulphur dioxide or total sulphurous acid). The proportion in the wine is measured by iodometry (free) and acidimetry (bound) and expressed in milligrams per litre (mg/l). Too much sulphur in wine is harmful to health, which is why there are legal limits. Even if these limits are adhered to, improper dry preservation of empty wooden barrels or over-sulphurisation of the wine can lead to the wine defect sulphuric acid firn.

Sulfur is the most common component of the human body, along with water, salt and calcium. It is one of the most important functional carriers in the organism, is necessary for the skin, hair and nails, keeps the tissue soft, relieves stress, is proven to help with asthma, arthritis, rheumatism, internal and external inflammation, back and muscle pain and all allergies. Sulphur baths are generally known as beneficial to health and are also used by many people. The body of an adult with an average weight of 70 kg contains around 150 g of sulphur. The daily requirement is estimated at just under 900 mg. Some sulphur compounds are toxic (poisonous) in higher doses. Sulphites can, for example, destroy the vitamins of the B group, inhibit the action of enzymes and increase the effect of carcinogenic substances. Foods rich in sulphur should therefore only be enjoyed in moderation.

The WHO (World Health Organization) has defined a safe health limit(ADI) for the daily intake of sulfur in the human body of 0.7 mg per kg body weight. Sulphur in food can cause allergies or other undesirable reactions. In the case of an allergy to sulphites, even much smaller amounts than those listed below can trigger the so-called "sulphite asthma". For this reason, since 25 November 2005 there has been an obligation to indicate on the label in accordance with the EU regulation if the sulphur content exceeds 10 mg/l (this value is exceeded for almost all wines). Permissible are the two texts "Contains: Sulphur dioxide" or "Contains: Sulphites" (the use of the formula "SO2" is not permitted, however). This provision applies to all products, i.e. grape must, wine, sparkling wine and vinegar (wine vinegar). The proportion of residual sugar is also relevant. The values since the EU wine market regulation valid since August 2009:

WINE TYPE (FA = free portion, KG = no limit value) RESTZ MG/L FA
Must, partly fermented must, storm, wine white/rosé < 5 g/l 200 KG
Must, partly fermented must, storm, wine white/rosé from 5 g/l 250 KG
Must, partly fermented must, storm, wine red < 5 g/l 150 KG
Must, partly fermented must, storm, wine red from 5 g/l 200 KG
Country wine white/rosé < 5 g/l 200 50
Country wine white/rosé from 5 g/l 250 50
Country wine red < 5 g/l 150 50
Country wine red from 5 g/l 200 50
Quality wine, Cabinet white/rosé < 5 g/l 200 50
Quality wine, Cabinet white/rosé from 5 g/l 210 50
Quality wine, Cabinet red < 5 g/l 150 50
Quality wine, Cabinet red from 5 g/l 200 50
Spätlese white/rosé < 5 g/l 200 50
Spätlese white/rosé from 5 g/l 300 50
Spätlese red < 5 g/l 150 50
Spätlese red from 5 g/l 300 50
Auslese white/rosé < 5 g/l 200 60
Auslese white/rosé from 5 g/l 350 60
Auslese red < 5 g/l 150 60
Auslese red from 5 g/l 350 60
Ausbruch, Beerenauslese, straw wine, TBA, ice wine < 5 g/l 150/200 75
Ausbruch, Beerenauslese, straw wine, TBA, ice wine from 5 g/l 400 75
Liqueur wine, quality liqueur wine white/red < 5 g/l 150 KG
Liqueur wine, quality liqueur wine white/red from 5 g/l 200 KG
Pearl wine white/rosé < 5 g/l 200 KG
Pearl wine white/rosé from 5 g/l 250 KG
Pearl wine red < 5 g/l 150 KG
Pearl wine red from 5 g/l 200 KG
Sparkling wine with carbon dioxide white/rosé < 5 g/l 200 KG
Sparkling wine with carbon dioxide white/rosé from 5 g/l 250 KG
Sparkling wine with added carbon dioxide red < 5 g/l 150 KG
Sparkling wine with added carbon dioxide red from 5 g/l 200 KG
Sparkling wine not rel. 235 KG
Sparkling wine when sold in Austria not rel. 275 KG
Quality sparkling wine (sparkling wine) not rel. 185 KG
Quality sparkling wine (Sekt) when sold in Austria not rel. 225 KG
low-alcohol wine not rel. 200 50
dealcoholised wine not rel. 200 KG
Fruit must, fruit wine, sparkling fruit wine not rel. 200 KG

For the production of organic wine, significantly lower quantities up to a maximum of two thirds of these maximum quantities are assumed. Individual organic associations oblige their members to do so. Thus Bioland prescribes a maximum of 110 mg/l (red wine) and 140 mg/l sulphur dioxide (white wine) for red and white wines with less than 5 g residual sweetness per litre. Wines with more than 5 g residual sweetness per litre may not contain more than 140 mg/l (red wine) and 180 mg/l (white wine) sulphur dioxide. See also a list of all wine ingredients under total extract.

All aids, work and measures in the vineyard can be found under vineyard care. Complete lists of the numerous vinification measures or cellar techniques, as well as a list of the types of wine, sparkling wine and distillate regulated by wine law are contained under the heading Vinification. Comprehensive information on wine law can be found under the keyword wine law.

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