The Sulphur Situation

Sulphur is a naturally occurring element that has been used for centuries in winemaking and grape growing. Its presence in these fields is as essential as it is controversial.  Sulphur treatments play a pivotal role in maintaining the quality and stability of wines, however they are also a subject of concern for those sensitive to its effects.  It is usually the outright villain in the general wine-drinker’s mind – an easier scapegoat for a hangover than overindulgence – without giving much consideration to its importance and the quantity in which it is present relative to other types of food and beverages.


The first specific mention of Sulphur’s use dates back to a German decree in 1487 that allowed growers to burn sulphured wood chips in barrels used for storing wine.  The process that then developed was termed ‘wicking’; whereby sulphur candles were burned inside empty, clean barrels before they are used again.  In modern day it is general practice to use sulphur in a powder or gas form.


One of the primary sources of sulphur in the vineyard is elemental sulphur, which is often used as a fungicide to prevent the growth of various vineyard diseases; such as powdery mildew and downy mildew.  Its application helps maintain the health of grapevines and grape bunches, promoting optimal grape maturation, safeguarding grape yields and quality.  By using sulphur carefully in the vineyards, viticulturists can reduce the need for more aggressive chemical treatments that might have undesirable ecological impacts.


In addition to elemental Sulphur, Sulphur-based products (predominantly sulphur dioxide), are widely used in wineries for their preservative properties.  Sulphur dioxide (SO2) acts as an antioxidant, preventing wine from undergoing premature oxidation, which can lead to the loss of flavours, colours, and aromas.  It also has antimicrobial properties to help control the growth of unwanted bacteria and yeasts, ensuring the stability and longevity of wines.


Sulphur dioxide is added at different stages of winemaking.  During crushing and pressing, it helps control the enzymatic browning of juice and pulp.  It also aids in clarifying must (grape juice before fermentation) and protecting it from oxidation.


During fermentation and aging, SO2 continues to act as a preservative, preventing microbial contamination and maintaining the wine’s overall stability.  Without adequate sulphur management, wines can become prone to spoilage, affecting their quality and shelf life.


Some individuals are sensitive or allergic to Sulphur compounds and can experience adverse reactions, such as headaches, respiratory issues, or skin irritations.  This has led to debates surrounding the appropriate levels of sulphur in wines.  These concerns have driven winemakers to explore alternative methods for preserving wines, and take extra precautions such as natural winemaking techniques to minimise or eliminate sulphur usage.  It is important to know, however, that SO2 can form as a byproduct of alcoholic fermentation.  Therefore, ‘natural’ wines that contain “no added sulphur” can still have SO2 present.


While many people are adamant that sulphites (a general term for a group of chemicals including sulphur dioxide and sodium or potassium metasulphite) in red wines are responsible for their drinking related headaches, red wines typically have lower sulphite levels.  Tannins from grape seeds and skins help prevent oxidation in red wine requiring lower use of SO2 to achieve stability in wines.  White wines are more prone to oxidation as they are not kept in contact with grape seeds or skins and therefore are generally given larger doses of SO2.


The more likely cause for resultant headaches (besides possibly drinking a few too many glasses of wine) are other irritants called Biogenic amines.  Biogenic amines, such as organic nitrogen compounds, are produced naturally during winemaking.


They include compounds like histamines and tyramine.  Unlike sulphites, these substances can cause immune responses, exhibiting symptoms such as headaches or a stuffy nose.  It’s also important to note that just because a wine is “natural” that doesn’t mean it has lower biogenic amines.  Wild or natural fermentations can sometimes increase the chance of compounds like histamine and tyramine forming.


In short; your ‘natural’ wine is just as, if not more, likely to give you a headache!

The ongoing debate regarding Sulphites in wine gets increasingly interesting when comparing levels present in other popular food and beverage items. According to the research, if you are sensitive to sulphites, French fries, dried fruit, or packaged meat may sadly be an issue for you too!


When asked if remaining under the maximum permitted sulphur levels was a particularly difficult task, Bobby Wallace of Paul Wallace Wines and Off the Record Wines in Elgin explained that “the more reductively you work with your wines the easier it is to maintain lower SO2 levels.  Certain cultivars are slightly more difficult to work with especially those with lots of aldehydes present as they tend to absorb more sulphur.  It also has to do with how well the first initial sulphuring after fermentation is taken up.”


He went on to explain that warmer regions can have slightly higher sulphur level as their pH is often higher than cooler areas and therefore the risk of microbial spoilage is higher.  Generally barrel ferments and skin contact wines have higher levels of sulphur compounds present.”


Different countries have different regulations regarding the total maximum limits of sulphur compounds in wine.  The Oxford Companion to Wine mentions the maximum limits as follows:

  • South Africa: 150 mg/L for dry reds, 160 mg/L for dry white, rosé, and sparkling, and between 200 and 300 mg/L for sweet wines depending on style and level of sweetness.
  • EU: 150 mg/L in dry reds, 200 mg/L in dry whites and rosés, 235 mg/L in sparkling wines, and 250 mg/L in sweet white and rosé wines. Some really sweet wines such as Sauternes from Bordeaux may contain up to 400 mg/L.
  • Argentina: 130 mg/L for dry reds, 180 mg/L for dry white and rosé wines and sweet reds, 210 mg/L for sweet white and rosé.
  • Chile: 300 mg/L for all dry wines and 400 mg/L for sweet wines.


The USA has an upper limit of 350mg/L and therefore, as one can see, not all permitted levels of sulphur are equal depending on their specific country’s set of regulations.  This is where knowledge is power if you are on the hunt for lower levels of SO2 in your wines.


Despite the controversy, the use of sulphur in producing high-quality wines remains paramount.  Striking a balance between the benefits and potential drawbacks is an ongoing challenge for winemakers seeking to cater to diverse consumer preferences and needs.


This blog was edited and posted by Digital Squeak.