Oct 25, 2019

What if my Fermenting Wine has a Sulfur Smell?

Hydrogen sulfide (H2S) is the rotten egg odor you smell, and it usually forms at the end of fermentation. Most home winemakers won’t notice a smelly problem until the first racking. If you do smell rotten eggs, the quicker you can act, the better your chances of saving the wine. If your wine is not treated promptly, hydrogen sulfide will react with other carbon compounds in the wine to create mercaptans, and later into disulfides. These are extremely difficult to remove from your wine once they are present, so the faster you can detect and treat your wine for hydrogen sulfide, the better.

How To Get Rid of Sulfur Smell in Wine

Many sources suggest that you add copper sulfate to your wine, but Midwest strongly advises against this. While a very, very, VERY small amount of copper sulfate will take care of your H2S problem, it is poisonous. DON'T USE IT. Big wineries sometimes use copper sulfate, but Midwest suggests a kinder, gentler approach, using chemicals that most winemakers already have on hand.

  1. First, measure the level of sulfites in your wine using an SO2 Test Kit. If the wine is deficient, treat the wine to 50 p.p.m. sulfites.
  2. Next, rack the wine two or three times, making sure to splash it around a lot as the wine is transferred between vessels. This aeration introduces oxygen to the wine, and will help counteract the hydrogen sulfide. This in turn removes sulfur, and thereby the smell.
  3. Replace the airlock, and let it sit overnight. This should take care of the problem in most cases.
  4. By now, that stinkiness should be greatly reduced. If you STILL detect a smell of rotten eggs, try Gelatin Finings in the amount stated on the package.
  5. Afterward, be sure to fine the wine with Bentonite or Sparkolloid according to package instructions. Either of these will remove the H2S. Then filter to remove the fining agent.

The other question to ask is why did this arise?

Common causes are too much sulfites at the start of fermentation, insufficient nutrients, and/or bacterial infection. So be sure to add Yeast Nutrients, add proper Sulfite at appropriate levels, and use a good sanitary process.

Check out our Bottled Knowledge section for more information on How to Make Wine at Home