What are Sulfites in wine?
"Sulfites" means first sulphur dioxide (SO2), one of the natural by-products of the alcoholic fermentation, an anaerobic complex reaction that transform sugar into alcohol. Of course, SO2 occurs naturally in all types of wine. Its level is directly linked to the main yeast used and is between 5 and 80mg/l. Most of wine makers use commercial neutral yeast (exogenous) that normally lead to approximately 20 mg/l of “natural SO2” in the wine.
Usually sulfitation agents are used to make the wine too. Indeed, very often wine makers choose to add a little extra at different phases of the process to prevent any growth of undesirable yeasts (i.e. brettanomyces), bacteria and microbes, as well as to protect against oxidation. In relation to residual sugar, wine sulfites are logically highest in sweet, white wines, and lowest in dry, red wines.
Actually, “Sulfites” generic term covers all sulphur derivatives, sulphur dioxide of course but as well sulphuric acid, Potassium bisulfite, Potassium metabisulfite, Potassium pyrosulfite, Ammonium bisulfite, Ammonium sulphate. Those Ingredients may be expressed differently especially on food labels as E220 (Sulphur dioxide), E224 (Potassium metabisulfite) or E228 (Potassium bisulfite), not to mention E150b, E150d, E221, E222, E223, E225, E226, E227 and E513 which use is forbidden for the wine making process (EU regulation) but authorised as food additives or/and processing aids. Quite a lot of stuff isn’t it.
Note: Ammonium bisulfite, Ammonium sulphate are not authorised by the EU regulation for organic wines
A bit of history about sulfite
Ancient cultures in Greece, Rome, and Egypt, already used sulfites to sterilise their containers of wine.
Sulfites use as wine making ingredients started from the 18th century to improve wine conservation. It’s undoubtedly the oldest oenological agent, still significantly used nowadays. Actually, no equivalent has been found so far to replace sulphites. It’s possible to use a combination of ascorbic acid (antioxidant), potassium sorbate (to stabilize and protect against unwanted yeast) and even implement hard filtrations but with no absolute guaranty of good and durable results at the end.
What are Sulfites properties?
So numerous that wine makers consider them as miracle ingredients and used them all along the wine making process. Just have a look hereafter:
- Antioxidant & antioxydase
> Protect must and wine from the oxygen action;
> It prevents development of bacteria and unwanted yeasts such as Brettanomyces. It is used as well for cleaning barrels, tankers and equipment;
- Antifungal against fungi and moulds;
- Fermentation stabiliser
> Destroy the weakest yeast and hence help select the most efficient and active one for the alcoholic fermentation. It is also used to stop and block the alcoholic fermentation (operation called sulphur mutage). ;
- Dissolvent property regarding grapes cells
> Speed-up the release of their contents, especially from the skin (anthocyanin, tannins and flavours);
- Acidifying agent that help reduce wine pH ;
- Flocculating and fining agent
> SO2 gathers colloid sediments and make them precipitate hence ease the filtering process
Ever since EU Legislation has required wine labels to disclose “Contains Sulfites” consumers have become increasingly concerned and sometimes worry as to whether sulphites are dangerous to one’s health.
There is normally little reason to worry. As we explained, sulfites are naturally occurring elements in all wines, very often generated in amount between 6 to 40 parts per million (ppm) (other said mg/l or mg/kg) and they are present in many other foods too as preservative ingredients. The major health risk involving sulfites would be allergic reaction. While it’s listed as a food allergen, a true allergic reaction in the form of anaphylaxis is fortunately a very rare phenomenon.
Actually, the main concern may be the daily cumulative dose we ingest when eating foods and drinking alcoholic beverages, as people seem increasingly becoming sensitive to sulfites. Hence, the World Health Organization has fixed at 0.7mg/kg the Acceptable Daily Intake (ADI) of sulfites. That means a man that weights 80kg should not ingest more than 56mg every day, respectively around 40mg for a woman and 10-15 mg for a child. EFSA has demonstrated that the cumulative intake for men, women and children very often exceed the ADI.
Wine regulation about sulfites
First, have a look at some sulfites limits fixed by country Food standard administrations and wine laws for conventional dry wines:
- 350 mg/l in the USA
- 300 mg/l in Chile
- 250 mg/l in Australia and New Zealand
- 150-200 mg/l (red – white) in the EU
- 130-180 mg/l (red – white) in Argentina
- 150-160 mg/l (red – white) in South Africa
Even if lower than they used to be, those limits remain relatively high, especially if you consider that 50mg is the sulfite quantity you will get if you drink 2 glass (0.125 litre) of wine with a “total sulfite” concentration of 200mg/l (EU regulation maximum permitted level for conventional dry white wine). That’s why organic wine regulations, and even more biodynamic and natural wine associations have sat up more restrictive limits.
Since 2005, EU regulation impose to give information on the label regarding allergens contain in the wine. It is particularly the case of sulfites. “Contains sulfites” has to be mentioned if concentration exceed 10mg/l. Otherwise the wine is considered as “Sulfite Free”.
As USDA organic wine regulation is very restrictive (10 mg/l as MPL, Maximum Permitted Level) and forbid any addition of sulfites during the wine making process, it's worth mentioning that sulfites concentration is respectively authorised by EU organic wine regulation up to 100mg/l for a dry Red wine and up to 150mg/l for dry White and Rosé wines. Therefore organic wines from EU may contain sulfites significantly. This is why it's interesting for our customers to look for biodynamic and natural wines which sulfites content is very often lower than organic wines.
Note: Since 2012, a mandatory analysis of the wine has to be done to detect any potential allergen. The use of egg white or milk derivative input has to be written on the label as well. Those processing aids are generally used to fine and filter the wine.
Summary tab regarding sulfites regulation for wine :
Do sulfites cause headaches ?
People may believe that sulfites in wine cause headaches which through research have not been proven so far. There has been no strong correlation between sulfites and headaches.
Sensitive people to sulfite may obviously encounter headache issues when drinking wine, especially white which very often contain more sulfites. But more common reaction to sulfite for those people are symptoms in the form of digestion issues, asthma-like symptoms, sinusitis, rhinitis, itchy skin rash that can occur straight or many hours after ingestion.
Actually many researchers suggest headache issues may be associated with presence of fermentation by-products as biogenous amines (putrescine, histamine, tyramine …), molecules that occur during the malolactic fermentation (second fermentation).
Another assumption is that headaches could be caused by ethanol (alcohol) which has already been witnessed for some people.
Wine is a beverage that must be savoured and of course drunk in moderation. In case of over consumption, consider hydrating yourself before going to sleep. It’s important to drink some water because alcohol has a dehydrating effect that contributes to hangover and related headaches.
APPENDIX : Sulfites in food – sample of MPL (Maximum Permitted Level) within the EU regulation to compare with wine regulation
Full EFSA document to read Here