Using Egg Beater to Rid of H2S

[montebello-wino]

Hi all,

I am an obvious beginner to winemaking, having made about 6 batches over the last few years. Most of the batches have been disgustingly inundated with H2S.

I have learned, through this forum, that the probable cause has been a lack of proper yeast nutrient at the proper time, but before learning this I have been using an egg beater to whip up the wine after it's first racking and before placing into carboys. It seems to work well. I've tried "splash racking" the wine, but that didn't do the trick -- hence the egg beater.

Two questions:

1. In all the recipes that I've read, I've always seen that the yeast nutrient is to be added at the same time the yeast is pitched -- but here on the forum I read that it ought to be added sometime AFTER the yeast is pitched. Why don't the recipes reflect this important step?

2. Any thoughts about using and egg beater to rid the wine of H2S?

Thanks

 

[BernardSmith]

Hiya montebello-wino, and welcome. My two cents:
1. an egg beater is fine because one way of removing H2S is to whip air into the wine. One common reason for the yeast's production of hydrogen sulfide is a lack of oxygen and whipping air into the wine either adds O2 or the action of whipping the wine allows the H2S that has been produced to off gas more easily. Other reasons for the production of H2S is a lack of nitrogen and other nutrients.

2. If you add nutrients too soon then you may be creating two problems. A) if the yeast has yet to rehydrate some of the compounds in the nutrients may damage the yeast cells (this is why you don't add basic nutrients when you rehydrate yeast. Go Ferm , for example is one preferred rehydrating nutrient mix NOT fermaid O or K) and B) if you are pitching a relatively small colony of yeast relative to the sugar content of the must then by adding nutrients while the yeast is in their lag phase you are in fact feeding other bacteria and fungi and not your yeast and so you are creating an environment in the must that may not favor the yeast you selected. If you wait 24 hours after the yeast you pitched are very active then you are feeding them and not any competing microbes.

So, this is my thinking but others with far greater expertise than I have may have very different ideas.

 

[sour_grapes]

One common reason for the yeast's production of hydrogen sulfide is a lack of oxygen

Is that true? I don't think I have seen that asserted on WMT before.

As you also said, H2S production is related to lack of N-bearing nutrients.

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.

As John points out, we are extraordinarily sensitive to H2S and thiols (larger SH-containing molecules). That is why they add a tiny (ppm) amount of methane thiol to your natural gas supply, so that you can smell when you have a gas leak. This is good for gas-leak detection, but the unfortunate result for winemaking is that we cannot tolerate very much H2S excretion by our pet yeasts.

 

[montebello-wino]

Thanks Bernard,

But I've also read here that too much oxygen (via beating with an egg beater) is BAD. I'm a bit confused about this whole O2 thing. I've read that primary fermentation is to be done in an open fermenter (with a cloth covering) to allow the yeast the O2 that it needs, while secondary fermentation is do be done in the absence of O2 (sealed in a carboy with water lock).

I've been beating my wine AFTER primary fermentation, prior to placing it a carboy -- and am wondering if this is not the cause of some off-tasting wine (not H2S but off tasting in other ways)?

 

[stickman]

Just my opinion, I generally agree that oxygen during the alcoholic fermentation of red wine helps reduce yeast stress, which plays some role in reducing H2S formation, but probably wouldn't solve an H2S issue related to major nutrient deficiency or other significant cause. Plenty of research has been done, but as usual winemakers have to decide how to apply the information to their particular wine. The question is how much oxygen and what variables should be considered when making the decision. I've been aerating my red wines during fermentation for many years, but the grapes I'm using are very tannic, so I've always felt they can handle oxygen with less concern.

If you search "wine macro-oxygenation" you'll find a huge amount of information, and there will always be some conflicting information, but I think Shea Comfort did a good job of summarizing the information for the MoreWine Manual.

 

[sour_grapes]

Nice to learn!

 

[bsc_so_cal]

Just a thought...
I think the important thing here - is to understand your limitations as a small winemaker. If you can't test your crushed grapes for existing nutrient levels - then it is better to do less when it comes time to add nutrients.

In my 5 years of making wine - the only time I've added nutrients is when the fruit was harvested in "significantly" less than optimum conditions. And even then I was very reluctant to add nutrients. My experience and several other local winemakers in my area have found that the addition of nutrients can be the culprit in a HS2 problem.

Try your fermentation without nutrients next time - or do a controlled experiment - with half of the batch with nutrients and half without. My bet is that your HS2 issue is being caused by adding nutrients when they aren't really needed.

 

[stickman]

I agree, it would be great to always have grapes with adequate natural nutrition, but I haven't been that lucky. I can only speak for myself, but when I started making wine I didn't use any nutrients and had H2S twice in 5 years, so I've already done the experiments. I decided at that time I had to figure out what was going on, or I might as well throw in the towel. If I had never experienced H2S then I probably wouldn't have looked for a solution.

Often I see suppliers that sell "Nutrients" that is nothing more than DAP, or sometimes a mixture of DAP and urea, and I suspect that is one of the problems for a beginner. Large doses of this type of inorganic nitrogen (when used alone) has been reported to potentially cause several different issues including H2S, however, most current research indicates that DAP can be used to supplement very low YAN musts, as long as it is used in addition to a good complex nutrient that contains organic nitrogen sources as well as vitamins and minerals.

Conservative nutrient guidelines suggest around 150ppm initial must YAN as a minimum to allow fermentation completion, but there are many other factors that influence that number. I typically have the initial must YAN data, so I'm not so conservative and routinely add enough nutrients to reach a combined YAN of 300 to 325ppm. The Fermaid K general addition rates of 2g/gal total will yield around 50 to 55 ppm YAN, which is a conservative addition that is not likely to push the must total nitrogen content to the extreme high end of the range. Most people fermenting grapes seem to do well with the standard Fermaid K addition rates.

If a fermenting must starts producing H2S at 5 brix, then the window for nutrient addition has already been missed, so if you don't have the must initial YAN data, then it may be best to make the standard addition of a complex yeast nutrient when you have the opportunity in portions before 12brix.

 

[montebello-wino]

S

Just my opinion, I generally agree that oxygen during the alcoholic fermentation of red wine helps reduce yeast stress, which plays some role in reducing H2S formation, but probably wouldn't solve an H2S issue related to major nutrient deficiency or other significant cause. Plenty of research has been done, but as usual winemakers have to decide how to apply the information to their particular wine. The question is how much oxygen and what variables should be considered when making the decision. I've been aerating my red wines during fermentation for many years, but the grapes I'm using are very tannic, so I've always felt they can handle oxygen with less concern.

If you search "wine macro-oxygenation" you'll find a huge amount of information, and there will always be some conflicting information, but I think Shea Comfort did a good job of summarizing the information for the MoreWine Manual.

Stickman, your attachment had very good information that totally changed my understanding of the effects of O2 during winemaking.

But for home wine makers like me, how in the world am I to know how to precisely monitor the amount of O2 being introduced as described in the article?

Thanks

 

[stickman]

There are very few absolute answers with wine, so it's a flexible process. For most home winemakers there is no precise monitoring of O2, it's mostly about managing the technique of each action. In addition, each step in the process depends to some extent on what happened before it. The standard wine making procedures are just a guide, and most people start there and then make adjustments to the procedure based on the results. Plenty of people here can help, but you may need to provide more information about the type of wine and your process.

 

[bluecrab]

It appears one can accurately predict when H2S will occur, due to lack of oxygen during fermentation.

"Opus One Winery in Napa Valley conducted a two-year research project in conjunction with UC Davis (UCD) to measure and monitor oxidation reduction potential (ORP) during red wine fermentations that proved to be an effective parameter to analyze fermentation dynamics. ORP is an effective indicator of yeast metabolism in fermentation and when it drops below a certain level, the fermentation enters a “reductive danger zone” where unwanted hydrogen sulfide (H2S) formation can occur...

"...we now have a good idea what level the ORP can drop to during fermentation to potentially produce H2S, and we can then push the ORP to a safer level through oxygen addition with a timely pumpover.

"At Opus One, Walker said he saw ORP range from 400 mV to as low as 50 mV. The ORP value of must starts high, about 300 to 400 mV, but will begin to drop quickly with the onset of yeast activity and continues to drop as the yeast enter exponential growth. Walker found that when the ORP drops below about 200 mV, the fermentation enters a 'reductive danger zone' where the elemental sulfur can be reduced to H2S. By tracking ORP, Walker said, 'I could predict accurately when reduction would occur.' The Opus One winemaking staff confirmed that Walker’s ORP data accurately predicted reduction just before staff could begin smelling sulfur odors. The trials also demonstrated that higher pH and temperatures are associated with faster fermentations, leading to lower ORP values and more H2S character." [Tracking Oxidation Reduction Potential in Wine Fermentations]

For a home winemaker, ORP meters are available. The Apera PH60 has an optional ORP probe for ~$45. If you don't feel like spending the money, aggressive punch downs are probably sufficient to avoid H2S, related to lack of oxygen.

 

[user 36973]

Walker found that when the ORP drops below about 200 mV, the fermentation enters a 'reductive danger zone' where the elemental sulfur can be reduced to H2S.

The operative word is 'can' be reduced. I bought and used an orp electrode this fall. It did indeed drop from about 300mV to 150mV during fermentation. However the question is IF there is elemental sulfur present to reduce. (By the way, it takes upwards of 5min for the reading to stabilize) The original question did not provide info on the juice or grapes used. In the case of American or French-American hybrid grapes there should not be any sulfur since it tends to burn the leaves. Though I still have gotten H2S with those grapes if the nutrients aren't sufficient.

I've tried "splash racking" the wine, but that didn't do the trick -- hence the egg beater.

No, splash racking won't remove all the H2S because it isn't all volatilized and oxidized. Dosing with copper sulfate (or reduless) does the trick.

an egg beater is fine because one way of removing H2S is to whip air into the wine

Have to disagree on this only bc it is misleading. Yes, whipping air into the wine will oxidize some dissolved H2S but do nothing about mercaptans, thus will be only a temporary solution. Copper solves the rest of the H2S and there are other solutions to the mercaptans. The egg white proteins will serve as fining agents and remove negativity charged ions such as tannin, but will not remove H2S.