More on Sulphur in wine, now the negatives

By Tobias Webb

Following up from the last post, here’s the counter-point to the summary I added in the previous post about sulphur from the Berry Brothers and Rudd blog, from the same source.

More on Sulphur in wine, now the negatives - Sustainable Wine
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Again in quote and bullet point form, the author argues against using any more sulphur in wine, than naturally occurs. Here are his counter points to the last post, which argued that sulphur really isn’t such a big deal if you are careful in how you use it:

“Starting in the vineyard, sulphur can be sprayed on vines to help combat powdery mildew. SO2 is often added before fermentation to kill bacteria found on the grape skins; during fermentation (mainly of sweet wines) to stop yeasts fermenting and retain residual sugar; and after fermentation to prevent oxidation and remove any remaining bacteria or yeasts in the wine.”

  • “…dusting sulphur on the vines can lead to excess soil acidity, lowering pH, and ultimately inhibiting growth of the vine roots.”
  • “Even small additions of SO2 prior to fermentation – commonly at crushing to protect against oxygen – have been known to encourage the extraction of proteins. This has a particularly negative impact for white wines, which will then require greater quantities of bentonite to remove the proteins, which will in turn remove important flavour compounds.”
  • “A perennial problem with the presence of SO2 in the must (or the addition of it during alcoholic fermentation) is the formation of volatile sulphur compounds (VSCs) which are formed in the absence of oxygen through yeast and sulphur metabolism.”
  • “Hydrogen sulphide (H2S) and mercaptans are the most common compounds which are responsible for off aromas, and can destroy the organoleptic quality of a wine in miniscule quantities, being detectable at levels as low as one to two mg/l.”
  • “The continued use of SO2 has raised many eyebrows and it is certainly the most controversial component used in oenology, posing a serious health concern. Employees who handle the substance must take great care. Short-term exposure from five to 25 minutes at a rate beyond five ppm can lead to respiratory problems including bronchoconstriction and increased asthma symptoms.”
  • “Additions of SO2 in winemaking are strictly legislated: measured by parts per million or milligrams per litre, maximum levels vary from 350ppm in the US to 160ppm for red wines in the EU. In low concentrations, SO2 is mostly undetectable in wine, but over 50 ppm, it becomes evident in the smell and taste of a wine.”
  • “No wines are completely free of SO2 as tiny quantities are released as a by-product during fermentation; yet there are practices that can be made to ensure its additional use is kept to a minimum.”

The final point seems the most significant to me. Anything in concentration or large quantities is bad for you. Given SO2 does occur naturally, and has its uses in judicious quantities, the key question for wine makers, it seems to me, is “can you manage with what comes naturally, or do you need to add an extra, minimal amount to assist in making a better wine?”.

So far, aside from the hardcore folks in the natural wine movement, (who do still have some in the wines, just the minimum amount) the answer seems to be “yes”, that a little extra SO2 can and does help. I’m hoping that given the rigour of today’s food/health testing, and given how long SO2 has been around (particularly in other foods) that’s not a problem for human health. Used well, it doesn’t seem to distract from flavours, if the world’s top rated wines are any guide to go by.

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About the author

Tobias Webb

Toby Webb is co-founder of Sustainable Wine. He is also founder of Innovation Forum, a leading platform for change in sustainable supply chains. He has spent 20+ years working in business and sustainability and has spent ten years teaching the subject at various London universities. He advises a number of companies large and small on sustainability. Businesses he has worked with include Patagonia, Interface, Bayer, SOK Group, Boots/Walgreens, Metro, Unilever, Nestle, Reckitt Benckiser, Sainsbury’s, and many others. He co-authored the UK’s national CSR strategy for David Cameron from 2006-10. He has been organising events, advising, teaching writing, blogging and podcasting on sustainable business since 2001. His (non-wine) blog is at