Ways To Lower S-04 Acidity?

Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum

Help Support Homebrew Talk - Beer, Wine, Mead, & Cider Brewing Discussion Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
I've seen a lot of talk about how clean (the current incarnation of) s-04 is, but I tasted one of my recent beers along with an old bottle of a previous version of the same ale fermented with A-09 and found them surprisingly similar, although noticeably different.

The A-09 was fruitier overall, sweeter, with a definite orange flavor not found in the s-04 ale. But the two I just did with s-04 at 71F (closer to 22C) were quite estery with a pleasant English character. It's giving me what I want for what I am brewing, which is great since it's cheap and easy to work with (relatively fast, fairly attenuative, repeatable, flocculant, can survive shipping in the sunny South, etc). I do plan to try fermenting one cooler just to see what the yeast can do though.
 
Does anyone actually measure the final beer pH when referring to the “twang”. English yeast can be notorious for dropping pH significantly. Finished beer pH in the low 4s can definitely taste a bit acidic or twangy.

I know making a starter with dry yeast is technically wrong but from my experience with this yeast this can actually help prevent this yeast in particular from driving pH way down during fermentation and eliminating the “twang”.

Otherwise make sure the pH of your knock out wort is a bit higher, this can help final beer pH finish a touch higher.

And if you don’t have a pH meter, you should. It’s the best investment you’ll ever make. Brewing beer without a pH meter is like driving a car without a speedometer.
 
Here is another HBT thread about S-04 twang: Let's talk S-04 and tartness

Some quotes:

There is a small tartness that I've noticed from it when fermenting above 64-65 degrees.

When I first used S-04 in a brown ale, before I had ferm temp control, it just about made me vomit.
Tried it in a brown ale again at ~68F with some rudimentary control, still hated that sour apple twang it gave me.
Got good temp control and tried it again at 65F and it was almost palatable.
Tried it again at 63F and BINGO, totally different (and very enjoyable!) beast.

That's the key - the Whitbread B family tend to produce lactic acid when they're fermented warm.

Weirdly, Lallemand says the correct range for S-04 is 18-26°C (64.4-78.8°F)! I fermented at 64-66 (according to the Tilt, which seems to measure temps very well).

I don't have a pH meter and I'm not really interested in getting one. I trust Bru'n water for my mash pH calculations. But in this case, I wish I had one. Seems like a good Brulosophy experiment.
 
So4 makes pretty nice ciders! Not bone dry like wine yeast, but still dry. I think one of my ciders finished at 1.004 with s04, or thereabouts, and one at 1.008.

I've used it at 62F in ales, and thought it was pretty clean, but over that and it got tart with some esters (because it's an English strain I assumed).
 
It would be really interesting to see if the ph changes from "tasting tart from the fermenter" to "tasting normal after few weeks in the bottle".
I would assume the ph would stay the same or even drop due to bottle conditioning and increased floccuatuon
 
I wonder if the tart thing is only noticeable in certain beer styles. I've been using S04 for my imperial stout for nearly two decades now and have never thought of "tart" as a character in it...

Cheers!
Sounds to me like folks are experiencing acetaldehyde because they aren’t raising temp at the end of fermentation and giving the beer a chance to clean its self up. For those unfamiliar, it’s a precursor to ethanol and taste like Granny Smith apples or cider. Which would be a twangy tart character in the beer
 
Last edited:
Sounds to me like folks are experiencing acetaldehyde because they are raising temp at the end and give the beer a chance to clean its self up. For those unfamiliar it’s a precursor to ethanol and taste like Granny Smith apples or cider. Which would be a twangy tart character in the beer
This is what my yeast microbiologist friend told me last night in our weekly homebrew club zoom meeting. Reading through other threads (there is a LOT written about this yeast) S04 can drop out and not finish the job cleaning up acetaldehyde (or take a long time doing it). This 1.037 beer has been sitting at 1.015 for two days. I have a half packet of Notty in the fridge. I think I’ll make a small starter and kräusen the beer this weekend and transfer it into a keg and let it clean up and naturally carbonate. This is my standard procedure with lagers anyway.

I also noticed that they changed the recommended temperature range for this yeast. It used to be 59-68.
 
This is what my yeast microbiologist friend told me last night in our weekly homebrew club zoom meeting. Reading through other threads (there is a LOT written about this yeast) S04 can drop out and not finish the job cleaning up acetaldehyde (or take a long time doing it). This 1.037 beer has been sitting at 1.015 for two days. I have a half packet of Notty in the fridge. I think I’ll make a small starter and kräusen the beer this weekend and transfer it into a keg and let it clean up and naturally carbonate. This is my standard procedure with lagers anyway.

I also noticed that they changed the recommended temperature range for this yeast. It used to be 59-68.

Did it work?
 
Did it work?
Something worked! I did pitch a very active Nottingham starter into a keg and transferred the beer on to it with maybe 10g of whole leaf Worcester Goldings dry hop. It cleaned up the weird flavor and the beer ended up coming in 2nd in our club mild competition. The winner had a very similar recipe but used Imperial Pub yeast and his beer was just plain on target. Going to have to try that yeast next time. I’m done with S04. The beer did drop crystal clear, but looks aren’t everything.
 
Something worked! I did pitch a very active Nottingham starter into a keg and transferred the beer on to it with maybe 10g of whole leaf Worcester Goldings dry hop. It cleaned up the weird flavor and the beer ended up coming in 2nd in our club mild competition. The winner had a very similar recipe but used Imperial Pub yeast and his beer was just plain on target. Going to have to try that yeast next time. I’m done with S04. The beer did drop crystal clear, but looks aren’t everything.
Losing against pub is like losing against Kasparov in playing chess.

S04 is a great yeast! ... At the end you've won against everyone else, except pub.
 
Last edited:
Losing against pub is like losing against Kasparov in playing chess.

S04 is a great yeast! ... At the end you've one against everyone else, except pub.
The worst part was that my beer was the first one being judged, which is usually the kiss of death. But after tasting the pub version I knew it didn’t matter what the judging order was. We had 8 solid entries in our competition and it was a fun night.
 
I have been running a few experiments. Too many people report opposite performance from this yeast to write it off. There must be a process difference responsible for the tang, and we should be able to figure it out.

Earlier in the thread I reported 2 sequential brews that were good, but I kept thinking I was tasting a little sourness. I finally decided that both of them had the same tart off-flavor. Today I am starting to drink the first of 2 sequential brews that absolutely do not have the same tart off-flavor. However, it should be noted that they both did before fermentation was complete (I have a theory about this). The tangy brews were both pale and shared the same water treatment. The good brews were both very dark and shared a different water treatment scheme. This morning I put a third (from the same slurry) in the fermenter that is pale--it will (hopefully) determine whether the tart off-flavor is an artifact of the water chemistry alone.

I do not own a pH meter. I brew with well water that has 35ppm alkalinity and single-digit ppm of everything else and I use the Bru'ngard spreadsheet. I treat 12 gallons of water the night before and add no other minerals or acid during the brewday. I BIAB, start with a thick mash, and do a couple of infusions to get to full volume. I control fermentability by time spent at 145 and 158. Prior to the change I made for the recent good S04 beers, I was adding gypsom and calcium chloride to get calcium up to about 120ppm. I made a bunch of good English ales this way using Imperial Pub A-09 and WY1469. But what I noticed was that, while I could put the mash at any pH I wanted (per the model), the spreadsheet showed the pH of my final full volume of wort dropping to very low numbers. But I was making good beer until I tried S-04.

All that said, for the good S-04 brews, I used much softer water--soft enough to get the spreadsheet model to predict a pH of 5.5-5.6 for the full volume mash (total calcium=50-75). With a pale beer, this resulted in a pH prediction for the starting thick mash of way high. I don't have acid or a pH meter, so I added black patent to get it down to 5.4-5.5, and made a dark brown ale that is as good as anything I have brewed. I dry pitched 2 packs of S-04 into 6 gallons of 1.046 wort. The second brew (with 1/4 of the slurry) was a Guinness clone, in which I added a little baking soda to the mash (not the liquor) to get the predicted pH up to 5.4-5.5 for the starting thick mash. Bru'nwater predicted the full volume pH at 5.5-5.6.

My theory: there is an off-flavor produced by S-04 during fermentation that is either: 1. NOT produced when the wort pH is above some threshold, 2. is only cleaned up when the wort pH is above some threshold (my current favorite), or 3. not detectable when the wort pH is above some threshold AND/OR dark roasted grain is present in sufficient quantities.

I think #1 is not correct because I taste my beer a lot throughout fermentation and I tasted the flavor on both good beers before they were done. I think #3 is not correct for the same reason. Note that this is not simply acetaldehyde. I am very sensitive to it and have used its disappearance as a cue to cask in the past with consistent results. It might be acetaldehyde plus some other factor though.

As for how S-04 seems to work, I think it wants to attenuate about 73-78%, depending on wort composition, works though simple sugars in 2 days, but takes another 3-5 to drop the last few gravity points and clean up. Between 65 and 70 it leaves a soft sweetness, warm bread, and generic light fruit in the background, with no fusels or twang, assuming wort pH is on the high side. If wort pH is on the low side, it reliably leaves a raw biscuit dough sourness that is universally unpleasant. These are my results--actual temperature range might be a little broader.

I hope some other brewers (with pH meters) look into this further. If my recent findings hold, S-04, when used within certain easy-to-maintain parameters, might be the answer to the age old question "is there a decent English dry yeast?" As for me, I am out of S-04 packets. I am going to try the Nottingham/Windsor combo in the next few brews. But these 2 (maybe 3) beers are good enough that I will use S-04 in the future, despite almost swearing it off for good.
 
I have been running a few experiments. Too many people report opposite performance from this yeast to write it off. There must be a process difference responsible for the tang, and we should be able to figure it out.

Earlier in the thread I reported 2 sequential brews that were good, but I kept thinking I was tasting a little sourness. I finally decided that both of them had the same tart off-flavor. Today I am starting to drink the first of 2 sequential brews that absolutely do not have the same tart off-flavor. However, it should be noted that they both did before fermentation was complete (I have a theory about this). The tangy brews were both pale and shared the same water treatment. The good brews were both very dark and shared a different water treatment scheme. This morning I put a third (from the same slurry) in the fermenter that is pale--it will (hopefully) determine whether the tart off-flavor is an artifact of the water chemistry alone.

I do not own a pH meter. I brew with well water that has 35ppm alkalinity and single-digit ppm of everything else and I use the Bru'ngard spreadsheet. I treat 12 gallons of water the night before and add no other minerals or acid during the brewday. I BIAB, start with a thick mash, and do a couple of infusions to get to full volume. I control fermentability by time spent at 145 and 158. Prior to the change I made for the recent good S04 beers, I was adding gypsom and calcium chloride to get calcium up to about 120ppm. I made a bunch of good English ales this way using Imperial Pub A-09 and WY1469. But what I noticed was that, while I could put the mash at any pH I wanted (per the model), the spreadsheet showed the pH of my final full volume of wort dropping to very low numbers. But I was making good beer until I tried S-04.

All that said, for the good S-04 brews, I used much softer water--soft enough to get the spreadsheet model to predict a pH of 5.5-5.6 for the full volume mash (total calcium=50-75). With a pale beer, this resulted in a pH prediction for the starting thick mash of way high. I don't have acid or a pH meter, so I added black patent to get it down to 5.4-5.5, and made a dark brown ale that is as good as anything I have brewed. I dry pitched 2 packs of S-04 into 6 gallons of 1.046 wort. The second brew (with 1/4 of the slurry) was a Guinness clone, in which I added a little baking soda to the mash (not the liquor) to get the predicted pH up to 5.4-5.5 for the starting thick mash. Bru'nwater predicted the full volume pH at 5.5-5.6.

My theory: there is an off-flavor produced by S-04 during fermentation that is either: 1. NOT produced when the wort pH is above some threshold, 2. is only cleaned up when the wort pH is above some threshold (my current favorite), or 3. not detectable when the wort pH is above some threshold AND/OR dark roasted grain is present in sufficient quantities.

I think #1 is not correct because I taste my beer a lot throughout fermentation and I tasted the flavor on both good beers before they were done. I think #3 is not correct for the same reason. Note that this is not simply acetaldehyde. I am very sensitive to it and have used its disappearance as a cue to cask in the past with consistent results. It might be acetaldehyde plus some other factor though.

As for how S-04 seems to work, I think it wants to attenuate about 73-78%, depending on wort composition, works though simple sugars in 2 days, but takes another 3-5 to drop the last few gravity points and clean up. Between 65 and 70 it leaves a soft sweetness, warm bread, and generic light fruit in the background, with no fusels or twang, assuming wort pH is on the high side. If wort pH is on the low side, it reliably leaves a raw biscuit dough sourness that is universally unpleasant. These are my results--actual temperature range might be a little broader.

I hope some other brewers (with pH meters) look into this further. If my recent findings hold, S-04, when used within certain easy-to-maintain parameters, might be the answer to the age old question "is there a decent English dry yeast?" As for me, I am out of S-04 packets. I am going to try the Nottingham/Windsor combo in the next few brews. But these 2 (maybe 3) beers are good enough that I will use S-04 in the future, despite almost swearing it off for good.
I think the the connection mash ph and twang of the final beer is very likely not there. The yeast changes the environments ph to it's liking, no matter what ph it starts with (within reasonable borders of course). The yeast's preferable final ph should be the same no matter what, that's why I don't think that the initial ph plays a big role.

It's very interesting that you are noting that the tartness is disappearing with time. I've noticed the same and this fits perfectly with the habits of the notoriously impatient general home brewer, drinking their beers way too early.

Been there done that myself waaaaaaay to often!
 
Just to be clear, I'm not saying mash pH has something to do with the SO-4 twang. Based on what I see, it's the overall water chemistry. This is why I think some people report good results with this yeast only when being dark beers. For those people, I'm postulating that their "dark beer" water, when all is said and done, has way more alkalinity than their "pale beer" water. Regardless of what they do to get the mask pH in range.

As far as timing, I saw the flavor gone on the tenth day after pitching for one beer and day 4 for the other.
 
Just to be clear, I'm not saying mash pH has something to do with the SO-4 twang. Based on what I see, it's the overall water chemistry. This is why I think some people report good results with this yeast only when being dark beers. For those people, I'm postulating that their "dark beer" water, when all is said and done, has way more alkalinity than their "pale beer" water. Regardless of what they do to get the mask pH in range.

As far as timing, I saw the flavor gone on the tenth day after pitching for one beer and day 4 for the other.
Dark beer doesn't have more alkalinity as the alkalinity is removed by the acidity of the dark grist. It's basically gone once the malt hits the water, that's the whole point of adding for example baking soda.

But it could be connected to certain ion concentrations. Actual British brewing liquor is way more minerally than most us-ians would dare to add to their water.

This could be a reason for yeast from British origination to act weird.
 
Dark beer doesn't have more alkalinity as the alkalinity is removed by the acidity of the dark grist. It's basically gone once the malt hits the water, that's the whole point of adding for example baking soda.

But it could be connected to certain ion concentrations. Actual British brewing liquor is way more minerally than most us-ians would dare to add to their water.

This could be a reason for yeast from British origination to act weird.
Is the alkalinity removed or is it balanced? I was under the impression the both the positive and negative ions (generally) stay in solution, giving you a wort with more buffering capacity at whatever pH it finds equilibrium. Maybe we need a chemist--I'm just a mechanic.
 
Is the alkalinity removed or is it balanced? I was under the impression the both the positive and negative ions (generally) stay in solution, giving you a wort with more buffering capacity at whatever pH it finds equilibrium. Maybe we need a chemist--I'm just a mechanic.
No, they are not. They react and then they are basically "gone".
 
fwiw, I've been brewing ten gallon batches of a 1.107 OG imperial chocolate stout using S04 for many years using RO water with a TDS of 10 or less - so hardly any RA at all to start. That same RO water requires between 20 and 25 ml of 25% PA in the strike liquor for all of my other 10 gallon recipes, but for the stout I don't add any acid and live with a mash struggling to get above 5.19 at 70°F

If I was going to do anything different at all, I'd just hold back the 9 pounds of black (>300L) grains for 30~40 minutes. But tbh the beer always comes out wonderfully, which always leaves me wondering why so many folks are down on S04...

Cheers!
 
fwiw, I've been brewing ten gallon batches of a 1.107 OG imperial chocolate stout using S04 for many years using RO water with a TDS of 10 or less - so hardly any RA at all to start. That same RO water requires between 20 and 25 ml of 25% PA in the strike liquor for all of my other 10 gallon recipes, but for the stout I don't add any acid and live with a mash struggling to get above 5.19 at 70°F

If I was going to do anything different at all, I'd just hold back the 9 pounds of black (>300L) grains for 30~40 minutes. But tbh the beer always comes out wonderfully, which always leaves me wondering why so many folks are down on S04...

Cheers!
I think that dark beers are pretty much covering up almost everything, so it's hard to detect some off flavours in them. But on the other hand, s04 is also my personal favourite for dark beers :D .
 
Does anyone actually measure the final beer pH when referring to the “twang”. English yeast can be notorious for dropping pH significantly. Finished beer pH in the low 4s can definitely taste a bit acidic or twangy.
Assuming that in a lifetime of drinking cask beer, most of it has been in spec per Murphy's ("The acceptable range of pH for cask conditioned beers is 3·7 – 4·1 units") then I'd disagree.

However, having seen how even illustrious US commercial brewers abuse their English styles with inappropriate cellarmanship, I do wonder whether part of it is either how people are kegging S-04 beers, or how it responds to particular carbonation regimes. IME it's fairly common for British styles (particularly weaker ones - mild & bitter) made commercially in the US to have a definite bite from carbonic acid due to overcarbonation in kegging, so I wonder if part of it is that.

In the UK, low ABV traditional British styles are rarely served from keg, other than a handful of macro brands that are optimised for serving with 70:30 nitrogen:CO2 "Guinness gas" or a similar blend. You don't use 100% CO2.
 
If you two were to take a stab at an explanation of what I just witnessed, what would your best theory be?
I'd second this:
Assuming that in a lifetime of drinking cask beer, most of it has been in spec per Murphy's ("The acceptable range of pH for cask conditioned beers is 3·7 – 4·1 units") then I'd disagree.

However, having seen how even illustrious US commercial brewers abuse their English styles with inappropriate cellarmanship, I do wonder whether part of it is either how people are kegging S-04 beers, or how it responds to particular carbonation regimes. IME it's fairly common for British styles (particularly weaker ones - mild & bitter) made commercially in the US to have a definite bite from carbonic acid due to overcarbonation in kegging, so I wonder if part of it is that.

In the UK, low ABV traditional British styles are rarely served from keg, other than a handful of macro brands that are optimised for serving with 70:30 nitrogen:CO2 "Guinness gas" or a similar blend. You don't use 100% CO2.
 
I've been tasting them all flat, and continuously as they carb. Until this past year, 90% of my brewing was English ale served at about 1.2 volumes.

I did these last few brews in an attempt to isolate the process variable that separates the "S-04 won't make a good beer" people from the "I can't understand why people don't love S-04" people. The assumption that led me to do it is that both groups are being honest about their experiences and the mode of communication (forum posts) has made it difficult to put a finger on what's different.

I'm really interested in the imperial stout with RO data point. I think that might actually support my hypothesis, depending on the particulars. @day_trippr would you be willing to post the recipe and water volumes so I can plug into the spreadsheet I've been using?
 
I'm not being hardheaded here, by the way. I live in a hot, hot place with no local home brew shop. I'm on a desperate search for a dry yeast that will make a decent English ale.
 
@day_trippr would you be willing to post the recipe and water volumes so I can plug into the spreadsheet I've been using?

Sure! Here's the recipe. The actual liquor volumes used are 12.75g Strike, and 5.78g Sparge - out of 11 gallons in the HLT (needed to cover the hex).

1717282027159.jpeg


[edit] fwiw, I actually use four S04 packs...

Cheers!
 
Last edited:
I'm not being hardheaded here, by the way. I live in a hot, hot place with no local home brew shop. I'm on a desperate search for a dry yeast that will make a decent English ale.

Since you live in a hot place, what temperature are you fermenting at?

I've used S-04 a lot and while it can work out on the dry side, and perhaps slightly tangy compared to US-05, acidity has not been a problem with the (mostly light) ales I brew with it. I've found running fermentation temp in the 64-68F range produces the best results with this yeast.

I read though most of this thread, but it is late, if I missed your temp control description, my apologies.
 

Latest posts

Back
Top