How to Solve "Rotten Egg" Smell in Wine
Where does the smell come
from? | The causes of hydrogen sulfide contamination
Prevention of H2S | Treatment
| Conclusion | References
Ever smelled rotten eggs when you racked your wine? We sure hope
not, but if you have, your wine has been bitten by the dreaded hydrogen
sulfide bug. No one wants to drink wine that smells like rotten
eggs, so is there anything you can do to save the wine? You bet.
Better yet, we'll offer some tips that should help you avoid the
problem in the first place.
Hydrogen sulfide (H2S) usually forms at the end of fermentation,
but most home winemakers won't notice a smelly problem until the
first racking. If you do smell rotten eggs, the quicker you can
act, you'll increase the chances of saving your wine. If you tarry
too long before treating the wine, hydrogen sulfide will react with
other carbon compounds in the wine to create mercaptans, and later
into disulfides. These boogers are extremely difficult to remove
from your wine once formed, so the faster you can detect and treat
your wine for hydrogen sulfide, the better!
The possible causes of hydrogen sulfide contamination are myriad:
- Too much sulfites, usually the result of grapes being
dusted with too much sulfur during the growing season
- Lack of proper nutrients (nitrogen, yeast hulls) during
- Yeast combining with various forms of sulfur (some folks
swear that Red Star Montrachet yeast is notorious for causing
H2S, but we've never experienced this ourselves)
- Bacterial contamination due to poor sanitation technique
That being said, here are the things you can do to prevent H2S contamination:
- Add proper amounts of sulfites to wine
- If making wine from scratch (not from a kit), add a proper
amount of yeast nutrient prior to pitching yeast (Fermax,
- Use proper yeast for the wine you're making, and make
sure it has not passed the expiration date or gotten too hot in
- Maintain sanitary conditions for your equipment and must
(especially prior to pitching yeast)
If the cat's out of the bag and you've already got a rotten egg
smell, you could do what the big wineries do and add the correct
(teensy-weensy) amount of copper sulfate to your wine... but we
don't recommend you do that, unless it's a last resort.
The reason? Copper sulfate is poisonous! grapestompers recommends
a gentler, phased approach to solving this problem - if H2S is caught
quickly enough, you may be able to solve the problem with chemicals
you already have on hand.
Here's what we recommend you do:
- First, measure the amount of sulfites in your wine using
a test kit
- If deficient, treat wine to 50 PPM sulfites
- Rack and splash - rack your wine two or three times,
being sure to splash it around a lot as the wine goes from vessel
to vessel. The aeration (introduction of oxygen) will help counteract
- Put the airlock back on and wait a couple of hours or
overnight. If it still smells like rotten eggs, keep going...
- Get a piece of copper (i.e. copper flashing) from a home
- Pour the wine over the copper so that it runs over the
surface of the metal into a receiving vessel.
- Fine or filter the wine.
- By now, the sulfur smell should at least be greatly diminished.
If you can still detect a smell (we've heard that humans can detect
H2S in quantities as low as 2 parts per billion), you might try
to use an egg white or a gelatin fining agent and fine
your wine. Add normal amounts recommended by the manufacturer.
- Filter wine through a tight filter.
- When all else fails you can use copper sulfate on your wine.
A 0.1% solution added at about 0.5 ml per gallon, will give you
about 0.3 PPM copper sulfate in your wine. BE CAREFUL. Remember,
this stuff is poisonous. DO NOT EXCEED 0.5 PPM of copper.
- Fine your wine with a bentonite or Sparkolloid fining
agent. This will remove all the copper sulfate.
- Filter wine if necessary to remove fining agent.
A rotten egg smell doesn't necessarily mean you throw away your
batch of wine... it simply means your wine has a hydrogen sulfide
problem. It's easily treated if caught in the early stages, but
you can bring in the heavy stuff if need be. Of course, it's much
better to prevent H2S from forming in the first place, by ensuring
proper winemaking techniques and sanitation.
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