Fermentation funk odors

[verdot]

An update on this - I followed Cap Punchers suggestion and followed the scottlabs guidelines. The company was also quite helpful over email. I started with noblesse, splash racked as others suggested and later added Reduless. The issue seemed to persist which led me to believe the additives had not done the job. So another splash rack and left to rest for a few weeks. Upon sampling, the foul smell was almost completely gone and the fruit was now showing in the nose. No signs of oxidation. So the wine will likely be saved. Ph was 3.5 and TA 6.7 Thanks to everyone who gave tips.

 

[mgarnto]

Question for everyone, is it possible that people think they smell H2S but it’s actually something else?

Everywhere you look it says “H2S can only be solved by splash racking if you’re lucky or chemicals, but it not treated early there’s no way to fix it”.

Yet, there are plenty of anecdotes where people say it magically fixes itself. Or they tried and failed early on with chemicals but several months down the road it’s fine.

So either H2S isn’t the doomsday people claim, or it frequently gets confused for some other aroma.

 

[sour_grapes]

Question for everyone, is it possible that people think they smell H2S but it’s actually something else?

Everywhere you look it says “H2S can only be solved by splash racking if you’re lucky or chemicals, but it not treated early there’s no way to fix it”.

Yet, there are plenty of anecdotes where people say it magically fixes itself. Or they tried and failed early on with chemicals but several months down the road it’s fine.

So either H2S isn’t the doomsday people claim, or it frequently gets confused for some other aroma.

IMHO, the resolution to your last proposition is that H2S is detectable in minute quantities (like ppm). So you have a small amount of H2S, you smell it, but it dissipates to the ppb level where it "just adds complexity."

 

[reeflections]

Question: will splash racking under vacuum help or is the point to introduce oxygen?

 

[mainshipfred]

Question: will splash racking under vacuum help or is the point to introduce oxygen?

I have no proof of this though I would think vacuum racking might reduce O2, it definitely reduces CO2.

 

[reeflections]

I have no proof of this though I would think vacuum racking might reduce O2, it definitely reduces CO2.

So is the point of splash racking for removing the H2S odor to introduce O2?

IOW, it would be better to splash rack via siphoning?

 

[mainshipfred]

So is the point of splash racking for removing the H2S odor to introduce O2?

IOW, it would be better to splash rack via siphoning?

I'm fortunate to have only had an H2S problem one time. I can't remember if I pumped from one vessel to another or splash racked it under a vacuum. I do believe though that the splashing released the hydrogen sulfide and the vacuum sucks it out without introducing O2. There are tons of folks on here that can give a more scientific response and even disprove my theory.

 

[reeflections]

I'm fortunate to have only had an H2S problem one time. I can't remember if I pumped from one vessel to another or splash racked it under a vacuum. I do believe though that the splashing released the hydrogen sulfide and the vacuum sucks it out without introducing O2. There are tons of folks on here that can give a more scientific response and even disprove my theory.

Yes, I only had it once as well - with Skeeter Pee. I poured it from one open bucket to another and back again. That fixed it but I hated introducing that much O2 after the fermenting was almost done (1.000).

 

[sour_grapes]

Yes, vacuuming should help with H2S.

 

[reeflections]

Yes, vacuuming should help with H2S.

Thanks!

 

[winemaker81]

Question for everyone, is it possible that people think they smell H2S but it’s actually something else?

It's possible someone smells sulfite and believes it to be H2S. However, if you smell H2S in any quantity, there's no mistaking the odor.

With H2S there are 3 components: the cause, the H2S itself, and its fallout (mercaptans).

The cause is typically low nutrient levels stressing the yeast. If the wine is currently fermenting, add nutrient. To prevent H2S in the future, use a proper nutrient regimen and/or use a yeast that doesn't produce H2S.

The quick treatment for H2S is to splash rack and/or stir well. This drives off the H2S -- do it in a well ventilated area. H2S is flammable, although I'm told that there isn't enough in a wine to produce a real danger; that said, even if it didn't reek, I'd still use a well ventilated area.

I run a fan while working with my wines and have 2 windows in my winemaking area that I open, weather permitting.

Also add a double dose of K-meta. Add more sulfur to combat sulfur ? Yup -- H2S and SO2 are completely different compounds. SO2 protects wine by binding to contaminants, which includes H2S.

The heavy-duty treatment is to expose the wine to copper. Although the "old time" remedy was to rack over new pennies, this is frowned upon because copper is a poison and there is no way to determine how much copper is introduced into the wine.

Instead use a product such as Reduless, in which the dose is calculated. Then fine the wine to help remove residue.

Mercaptans can be formed with the H2S interacting with alcohol, producing off flavors and smells that do not go away on their own. A treatment for mercaptans is ascorbic acid, but go VERY light on it, as very little makes the wine acidic, sharp tasting. Also, IME it takes months to work -- do not add ascorbic acid, taste the wine a week later, and then add more.

Yet, there are plenty of anecdotes where people say it magically fixes itself. Or they tried and failed early on with chemicals but several months down the road it’s fine.

My guess is that H2S didn't "magically" fix itself. Either the person misinterpreted the smell, or they caught it early and something they did (add nutrient, add K-meta, stir, etc.) corrected the problem.

Regarding the wine being fine several months down the road? IME the treatment for mercaptans was not quick -- it took months, so the wine was fixed by the treatment.

 

[Rice_Guy]

@mgarnto H2S is an extremely reactive chemical, ie it will not stay in the wine as H2S gas. YES it will magically go away producing less volatile chemicals classed as mercaptans.

The danger in all this is that our ability to detect the desirable parts per billion fruity aromatics is covered over by the mercaptans so, ,,, you can produce a perfectly drinkable wine, ,,, which has meaty notes and might complement a dark chocolate candy, or as one of the gals in the vinters club says “fried chicken” flavor wines.

This post evaluates ten webinars,, “BOOK REVIEWs” related to air exposure (AKA redox potential) while making wine. - - - - - - - - - - - - - - - - - - - - - - - ->
This video is about half chemistry and half treatments which can be tried to change reductive flavors. Ie sulfides / threshold detection level/ latent sulfur changes (in bottle), YAN prevents yeast from forming sulfide compounds, it is easier to flush SO2 out early with yeast CO2.
* Managing ‘reductive’ aromas in wines; Speaker: Dr Marlize Bekker (The Australian Wine Research Institute) Webinar recorded: 7 November 2019 Additional resources: https://www.awri.com.au/industry_supp... Volatile sulfur compounds (VSCs) are known to cause ‘reductive’ aromas in wine, commonly described as ‘rotten egg’ (hydrogen sulfide), ‘putrefaction’ (methanethiol) and ‘rubber’ (ethanethiol). These compounds play important roles in determining wine aroma, consumer preference and the perception of wine quality. Therefore, the management of VSC concentrations in wines, whether from fermentation or 'other' origins, is an important consideration for winemakers. The main techniques used for VSC removal are oxidative handling and/or copper fining; however, the effectiveness of these treatments may be temporary, as the compounds can often reappear post-bottling when reductive conditions are re-established. This presentation will summarise the latest research on ‘reductive’ aroma formation in wines and discuss practical remediation strategies to manage these characters, 58 minutes (30 min. was Q&A)
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[winemaker81]

@mgarnto H2S is an extremely reactive chemical, ie it will not stay in the wine as H2S gas. YES it will magically go away producing less volatile chemicals classed as mercaptans.

Thanks for pointing this out. In my research on the topic, I've not read that the H2S will dissipate on its own, although it makes sense that it does so.

Essentially, the symptom (H2S stench) goes away, but is replaced by a permanent-unless-treated problem (mercaptans).

I learn something new every week on this forum.