# H2S during MLF?



## RonObvious (Jun 23, 2020)

So this has happened twice now - the first time I thought it was a fluke, but now I'm seriously wondering what's going on:

Red wine (first time was Marquette juice, second time was Chilean Merlot from grapes), primary fermentation goes well, numbers all look good, yeast nutrients added as usual. After fermentation is done, I rack into PET plastic carboys and add Wyeast 4007 to kick off MLF. I checked in a few weeks and found a horrible odor - rotten eggs, cabbage, gym socks, something in that vein. Panic set in and I immediately started H2S correction techniques by splash racking twice, stirring with a copper pipe and adding Sparkolloid. A week later the foul odor was somewhat better, but not all gone, so I splash racked again. The Marquette then went into a barrel for a few months, after which it smelled MUCH better and is really quite delightful now. The Merlot is still in a plastic carboy but smells substantially better. So I'm scratching my head as to why, twice in a row, I had H2S problems...

... then just today I noticed that I had a little bit of Marquette that I didn't have room for while racking back and forth and in and out of barrels - Months ago I put it in a 1 gallon carboy and haven't touched it since. In other words, this is 1 gallon of completely un-treated wine. For the past several months I haven't even wanted to look at it, much less open it, fearing the stench of death and putrescence that must surely be waiting for me. But today I finally summoned the courage to remove the bung and cautiously advance my nose... and guess what... it's GOOD! My wife thinks she still detects a tiny bit of cabbage odor, but I cannot. For the most part, the H2S smell is gone! And again, this is the UN-treated wine. No copper, no splashing, no fining, nothing but time. So what the heck? This begs several questions:

1) Does MLF ever cause H2S problems? Or some other related sulfur chemical?
2) If so, does the strain of MLB matter? I have always used Wyeast 4007 because it is convenient and seems to work). 
3) Does H2S ever clear up on its own?

Any advice is appreciated.


----------



## stickman (Jun 23, 2020)

H2S during MLF is usually related to the amount of lees present, as well as the adequacy of nutrients provided during AF and the resulting health of the lees. Once the AF is complete, or after pressing when using grapes, it's typical to rack off of the heavy lees within 1 to 3 days, often that's enough, but under some circumstances you may need to rack again in a couple of days if significant additional lees drop out and/or are producing H2S. It's a stage in the process where you have to keep your nose in the carboy.


----------



## RonObvious (Jun 24, 2020)

"Keep your nose in the carboy." LOL, I love that! Sounds like good advice stickman, thanks!


----------



## wood1954 (Jun 24, 2020)

You could try Avante yeast, it does not produce h2s at all.


----------



## DizzyIzzy (Jun 25, 2020)

stickman said:


> H2S during MLF is usually related to the amount of lees present, as well as the adequacy of nutrients provided during AF and the resulting health of the lees. Once the AF is complete, or after pressing when using grapes, it's typical to rack off of the heavy lees within 1 to 3 days, often that's enough, but under some circumstances you may need to rack again in a couple of days if significant additional lees drop out and/or are producing H2S. It's a stage in the process where you have to keep your nose in the carboy.


What on earth is H2S?........................Dizzy


----------



## stickman (Jun 25, 2020)

H2S is a chemical that smells like rotten eggs.


----------



## Boatboy24 (Jun 25, 2020)

AKA Hydrogen Sulfide


----------



## RonObvious (Jun 26, 2020)

Hadn't heard of Avante, wood1954 - thanks for the tip, I'll look into it!


----------



## Handy Andy (Jun 28, 2020)

Quoting from instructables "Hydrogen Sulfide removal: Copper sulfate is used to remove hydrogen sulfide and other reduced sulfur compounds which are the source of 'rotten egg' like smells. For best results, use as soon as possible after fermentation. If racking the wine once or twice during fermentation didn't eliminate the problem. Bench tests are used to determine the minimum effective dose. "

I googled Copper Sulphate addition to wine to find out what should be added and found this link Copper Sulfate Trial. I am not at this stage yet, but thought it might be useful


----------



## cmason1957 (Jun 28, 2020)

Handy Andy said:


> Quoting from instructables "Hydrogen Sulfide removal: Copper sulfate is used to remove hydrogen sulfide and other reduced sulfur compounds which are the source of 'rotten egg' like smells. For best results, use as soon as possible after fermentation. If racking the wine once or twice during fermentation didn't eliminate the problem. Bench tests are used to determine the minimum effective dose. "
> 
> I googled Copper Sulphate addition to wine to find out what should be added and found this link Copper Sulfate Trial. I am not at this stage yet, but thought it might be useful



Yes, you can add copper or copper containing products (redulees), but they are a somewhat harsh thing to use on thor wine. It is by fast better to make sure you give your yeast good nutrition during ferment, rather than dealing with the issue after the fact.


----------



## Handy Andy (Jun 29, 2020)

cmason1957 said:


> Yes, you can add copper or copper containing products (redulees), but they are a somewhat harsh thing to use on thor wine. It is by fast better to make sure you give your yeast good nutrition during ferment, rather than dealing with the issue after the fact.



I know nothing. What is good yeast nutrition, for the fermentation stage. Sugar ? Does a lack of yeast nutrition cause the rotten egg smell?


----------



## cmason1957 (Jun 29, 2020)

Handy Andy said:


> I know nothing. What is good yeast nutrition, for the fermentation stage. Sugar ? Does a lack of yeast nutrition cause the rotten egg smell?



Sugar is not nutrient. Fermaid-O, Fermaid-K, DAP are. Check out morewinemaking.com find their fermentation documents and read them, they go into great details about nutrients. It's feeding the yeast the minerals and vitamins they need to be happy and healthy.


----------



## wood1954 (Jun 29, 2020)

There are products on most online brew and winemaking Stores that sell fermentation nutrients, if your not sure call and ask one of the stores. It’s cheap and easy.


----------



## sour_grapes (Jun 29, 2020)

Handy Andy said:


> I know nothing. What is good yeast nutrition, for the fermentation stage. Sugar ? Does a lack of yeast nutrition cause the rotten egg smell?



And yes, you are exactly correct: the lack of yeast nutrition (nitrogen in particular) causes the rotten-egg smell. See my explanation below:



sour_grapes said:


> From my reading of the primary and secondary literature, this is my understanding of H2S production and its relation to N deficiency. Proteins are made of amino acids, and two important amino acids contain sulfur. The yeast has to provide the sulfur to form these compounds to the proper organelle during protein synthesis. It does so in the form of H2S, which it extracts from more complex sulfur-containing compounds. One organelle passes the H2S off to the organelle responsible for protein synthesis.
> 
> However, nitrogen is a major component of amino acids (hence the root _amine_, from _ammonia_.) If there is a dearth of N, the organelle responsible for synthesizing the sulfur-containing amino acid cannot do its job; this results in a surfeit of H2S, which the yeast then excretes.
> 
> ...


----------



## Handy Andy (Jun 29, 2020)

I know nothing. 

Does the type of SO2 added have an influence on H2S production ie liquid solution H2SO3, or Potassium metabisulphate K2S2O5. Is one better than the other with reference to H2S ?

Apologies for the stupid questions


----------



## cmason1957 (Jun 29, 2020)

Handy Andy said:


> I know nothing.
> 
> Does the type of SO2 added have an influence on H2S production ie liquid solution H2SO3, or Potassium metabisulphate K2S2O5. Is one better than the other with reference to H2S ?
> 
> Apologies for the stupid questions



Makes no difference. The H2S come is a byproduct of the yeast itself and nothing else. All yeast produce some, but when the yeast doesn't get enough nutrients it produces enough to cause us to notice. It is caused by lack of nutrients and stressing the yeast.

I might suggest you read this in depth discussion of how and why it is produced -



https://www.lallemandwine.com/wp-content/uploads/2017/05/WE-7-H2S-production-by-wine-yeast.pdf


----------



## Handy Andy (Jun 29, 2020)

cmason1957 said:


> Makes no difference. The H2S come is a byproduct of the yeast itself and nothing else. All yeast produce some, but when the yeast doesn't get enough nutrients it produces enough to cause us to notice. It is caused by lack of nutrients and stressing the yeast.
> 
> I might suggest you read this in depth discussion of how and why it is produced -
> 
> ...


Thanks for the link, it seems the selected yeast can reduce the chance of H2S smell in wine also, from your links summary

"Hydrogen sulphide (rotten egg) aroma is a serious fault in wine and will result in quality loss in the final product. Its production is mainly found during alcoholic fermentation. H2S production by wine yeast varies based on the yeast used as well as on the environmental factors, especially the assimilable nitrogen concentration and micronutriens present. Ranging from low to high producers, this characteristic is important to take into account, as well as the nutritional status of the must, when deciding on a fermentation strategy. 

The* best way to avoid formation of H2S during winemaking are to choose a low H2S yeast producer *and apply good fermentation practices, and also use wine yeast such as Lalvin Sensy™ which have been especially selected to avoid the production of this compound while keeping in mind a good nutrition and oxygen addition strategy. It is adapted to white winemaking fermentation where the conditions (such as low NTU, low temperature, low YAN) could affect H2S formation, and the *Lalvin Sensy™ with its low capacity to produce H2S, as well as SO2 and acetaldehyde, will let the varietal aromas be fully expressed*. "


----------



## cmason1957 (Jun 29, 2020)

Yes, some yeast are more likely to produce H2S than others, for me RC212 is one that has been problematic. But all yeasts, except for a few very new yeasts specifically bred to not be able to produce H2S, are capable of producing rotten eggs smells, if they don't have enough nutrients. The only real way to know how much you need to add is to measure the YAN (Yeast assimible Nitrogen or something like that), but I don't think many of us home winemakers measure that, from what I understand, it can be done.

There is a downside to the new yeasts that don't produce H2S, but I forget what it is. I have never used them. They don't seem to be readily available in the small quantities I would use.


----------



## RonObvious (Jun 30, 2020)

cmason, it's funny you mention RC212 because that is the yeast I used in both wines referenced at the beginning of this post. It would be a shame if I had to abandon it because we have done yeast trials (particularly with French/American hybrids like Marquette) over the past few years and have come to regard RC212 as our favorite. Yet this is twice in a row now that we've had to deal with H2S, so now I'm a little suspect of it...


----------



## cmason1957 (Jun 30, 2020)

RonObvious said:


> cmason, it's funny you mention RC212 because that is the yeast I used in both wines referenced at the beginning of this post. It would be a shame if I had to abandon it because we have done yeast trials (particularly with French/American hybrids like Marquette) over the past few years and have come to regard RC212 as our favorite. Yet this is twice in a row now that we've had to deal with H2S, so now I'm a little suspect of it...



It is a perfectly fine yeast, but anytime I use it, I would certainly go high on the nutrition. Depending on what characteristics you are looking for in your wine, I might suggest Asmunhasen (AMH) yeasty and I probably horribly spelled that. I have used it for Chambourcin and St. Vincent both and really like what it brings to the must. I also like BM4X4 and BM45.


----------



## RonObvious (Jun 30, 2020)

Thanks, we haven't tried AMH yet, but we have tried BM4x4. RC212 seemed to do a better job of softening hybrid grapes' acidity while maintaining the bold fruit aromas I like so much. Maybe you're right - just go generous on the nutrients and check frequently. I think I may bite the bullet and try Avante too - the promise of no H2S AND also munching down some of the malic acid sounds pretty appealing.


----------



## RPh_guy (Jun 30, 2020)

For those looking to learn more about H2S, I've covered this off flavor extensively on my wiki:
Hydrogen sulfide - Modern Brewhouse wiki

While bacteria can certainly produce H2S, I didn't come across any research specifically about MLF.

Cheers


----------



## JohnT (Jul 6, 2020)

You need to address H2S as soon as you can. H2S can (over time) bond into other nasty compounds (eg mercaptans) that are harder to address.

I recommend that you look into a product called redueless. It is not toxic like copper sulfsate and gives more control over copper dosage then simply exposing you wine to copper metal.

I use RC212 fr most of my red wines. I do 3 nutrient feedings during AF and H2S is a very rare occurrence.


----------



## RPh_guy (Jul 6, 2020)

JohnT said:


> You need to address H2S as soon as you can. H2S can (over time) bond into other nasty compounds (eg mercaptans) that are harder to address.


This has only been theorized, never proven.



JohnT said:


> I recommend that you look into a product called redueless. It is not toxic like copper sulfsate and gives more control over copper dosage then simply exposing you wine to copper metal.


Check out the article I linked in the previous post.

Arguably copper sulfate gives greater control over VSC removal than Reduless because you can more easily do a bench trial. It's not toxic when used appropriately. Reduless allegedly has fringe benefits though, if you want to solely rely on their marketing (which is dubious).


----------



## JohnT (Jul 13, 2020)

RPh_guy said:


> This has only been theorized, never proven.
> 
> 
> Check out the article I linked in the previous post.
> ...



It is a darn good theory. To get rid of mercaptans I use ascorbic acid / copper treatment. From my understanding, the ascorbic acid breaks the bonds, so that the copper can then address the sulfur issues. I am no chemist, and I am sure that you can argue the science, but this system works like a charm.

When dealing with H2S issues, you need to realize just how little of the stuff there is in wine. Just 1 ppm of H2S could knock you backwards. We are dealing with a very small scale. This is why I like redueless. It is more gentle and less toxic (I believe) delivery system then copper sulfate.


----------



## RPh_guy (Jul 13, 2020)

Your understanding is correct with regard to mercaptans and disulfides. However it's still unclear whether H2S contributes to forming these compounds.

Copper sulfate is *not* any more toxic than Reduless if the product is used appropriately. However, if the powder form is more convenient, then great (and Kupzit is also a good option for a powder). The liquid form does have a significant advantage though: being able to more accurately dose it via a bench trial.


----------

