S-04 attenuation vs mash temp

robsan77 · Feb 1, 2014

I've just done a 1040 g all pale beer. Mashed at 68c. Got a final gravity of 1012 which I thought was a bit high. I've not used s04 for such a long time and im used to us05 fermenting right down. The attenuation works out at 71%.

well aerated, pitched and temp controlled.

Does s04 respond well to mash temp? I find us05 doesn't and always ferments low whatever.

Good Ed · Feb 1, 2014

well with a 68C mash you won't get so much fermentable sugars, so maybe the attenuation is not far off. I get an average of 73% with SO4.

morethanworts · Feb 1, 2014

I just had 79% in an ESB with two packets of s-04 in 23L, 1052 to 1011, rehydrated, aerated, kept at 18C until for around 4 days then up 22C for a strong finish for 3 more. Mash was 66C for 90 mins. Maris Otter and 430g Crystal, some wheat and a tiny bit of black malt.

robsan77 · Feb 1, 2014

these are exactly the kind of posts I like to see. Ive not been able to find this information anywhere on t'net

Dr Mike · Feb 1, 2014

That sounds about right. My first AG was a TTL clone (99% PA, 1% Chocolate) mashed at 68C and I got 71% attenuation with S-04. With a 66C mash I got 75% attenuation (Summer Lightning clone - 100% PA).

I think the fermenation temperature also makes a difference. Those two were both fermented at 18C but with a recent brew fermented at 20C I got 78% and that was with 10% crystal malt in the recipe.

Bram · Feb 2, 2014

How long are you mashing for? I found that when I increased my mash time from 60 to 90 minutes at 67C the attenuation increased by a couple of degrees.

Dads_Ale · Feb 2, 2014

Had a similar experience with one of my beers recently. Was supposed to mash at 65c but ended up at 68c. PH was also a bit high. OG was 1040 and it only fermented down to 1017. one sachet of S-04 in 28lts. Not ideal but it has still turned out quite drinkable, especially so for a low ABV beer (about 3%).
I put the low attenuation down to a combination of high mash temp, high PH and under pitching the yeast.
I have now installed a probe thermometer in the mash tun and use two sachets of yeast. No problem now.

rodabod · Aug 19, 2015

Bumping this thread as I currently have a brew which is struggling to push below 1020 after an OG of 1042.

Mashed at 70c for extra body as its a low ABV brew. Brewers Friend reckons I should hit more like 1014. I use an accurate K-type thermocouple thermometer.

Temp held at 20c for the duration. A well aerated wort, and I pitched one sachet of hydrated yeast into a 5 gallon batch. Went off like a rocket for two days and then idled.

Added an extra 5g of rehydrated S-04 and roused existing yeast as it had already fallen bright. Also raised to 21c. It's fermenting, but very, very slowly.

Fingers-crossed I suppose. I'm used to using US-05 which sometimes goes beyond my attenuation expectations, but never less than.... I'm wondering if my yeast were overly active at the start of fermentation.

Covrich · Aug 19, 2015

robsan77 said:
I find us05 doesn't and always ferments low whatever.

Funny I always find it ferments out well I normally get 80% I would say

rodabod · Aug 19, 2015

Covrich said:
Funny I always find it ferments out well I normally get 80% I would say

I think there may be a difference in what is perceived as "fermenting well". I think all agree that US-05 seems to batter through to a low final gravity, even if a large quantity of the sugars are more complex.

Maybe I should have mashed 70c and used US-05, or mashed at say, 67c and used S-04.

It's all experience I suppose.

MyQul · Aug 19, 2015

rodabod said:
.. I'm wondering if my yeast were overly active at the start of fermentation.

S0-04 is a fast fermenter and can ferment out in as little as three days.

markcc · Aug 28, 2015

I made a porter using s-04 last week. Went like the clappers for three days and then went very quiet. I took the FG at 0.022 yesterday, an apparent attenuation of 70%. I was targeting 0.018, so have put it somewhere warmer and will rouse the yeast tonight to see if I can get it to drop a bit more. I mashed at 67oC for 1 hour, but the temp was bit over that for the first 5/10 minutes.

It's the first time I've used s-04 - it gave off a very strong banana aroma.

rodabod · Aug 28, 2015

Those esters you get do fade away with time, but I did find that they were worse when fermenting at a higher temperature.

I'm not sure how much I like S-04, but I'm going to persist as I know that it can work well.

HebridesRob · Aug 28, 2015

http://www.fermentis.com/wp-content/uploads/2012/02/SFA_S04.pdf
http://www.fermentis.com/wp-content/uploads/2012/02/SFA_US05.pdf

I'm not anything of an expert on the yeasts that are available nowadays but given the above plus the understanding that a 70c mash will produce a lot of unfermentable sugars, I think the results you got would be more or less expected.

peebee · Aug 28, 2015

Weird. I'd consider anything less than 1.012 to be abnormal. And I've been using S-04 for years now. [Most recently for very low alcohol brews (mashing at 68-9C I can still get 1.012 from an OG of 1.030). ---EDIT: Scrub this, I was using "Windsor" yeast for its well known habit of finishing high!---]

Talking of "abnormal", I tried that Safbrew "Abbaye" yeast the other day and got 1.008. That was from a bog standard 67C mash. And it took less than 48 hours to get there... from 1.061!

rodabod · Aug 30, 2015

Just added my dry hops (lots of them... Maybe 80g or so) and fermentation has kicked off again. Will see how far it goes.

simonk68 · Sep 3, 2015

markcc said:
I made a porter using s-04 last week. Went like the clappers for three days and then went very quiet. I took the FG at 0.022 yesterday, an apparent attenuation of 70%. I was targeting 0.018, so have put it somewhere warmer and will rouse the yeast tonight to see if I can get it to drop a bit more. I mashed at 67oC for 1 hour, but the temp was bit over that for the first 5/10 minutes.

It's the first time I've used s-04 - it gave off a very strong banana aroma.

Hi New to forum, just brewed my first porter and I think I may have made a mistake by using S-04, I was aiming for a high alcohol 8% beer, had a starting SG of 1.078 which was pretty much spot on to what I was aiming for, I was looking for final SG of 1.017. Had a mash temp of about 66degC. It fermented like the clappers for one day then has just about stopped, checked SG and it is 1.034, still decent at about 5.9% but not what I was after, I have tried giving it a good stir but dosnt seem to have re started it. Do I just leave it or can I throw in another packet of yeast, I have a spare packet of S-05. its a 15 litre batch. used to using S-05 which always ferments out fully. Any suggestions? pointers?

markcc · Sep 4, 2015

simonk68 said:
Hi New to forum, just brewed my first porter and I think I may have made a mistake by using S-04, I was aiming for a high alcohol 8% beer, had a starting SG of 1.078 which was pretty much spot on to what I was aiming for, I was looking for final SG of 1.017. Had a mash temp of about 66degC. It fermented like the clappers for one day then has just about stopped, checked SG and it is 1.034, still decent at about 5.9% but not what I was after, I have tried giving it a good stir but dosnt seem to have re started it. Do I just leave it or can I throw in another packet of yeast, I have a spare packet of S-05. its a 15 litre batch. used to using S-05 which always ferments out fully. Any suggestions? pointers?

Sounds similar to what I was aiming for. OG was 0.077, but gravity is now 0.018 after two weeks (which is about 75% attenuation, so pretty much max for S-04). It went hard for three days and then really slowed, but did keep fermenting. I used one packet in 17litres having mashed at 67oC.

Not really sure what to recommend - I'm pretty new to brewing!

Have you tried raising the temperature a bit? Also, did you oxygenate well at the beginning?

Edit: just seen your other thread - looks like there's nothing to worry about!

simonk68 · Sep 4, 2015

markcc said:
Sounds similar to what I was aiming for. OG was 0.077, but gravity is now 0.018 after two weeks (which is about 75% attenuation, so pretty much max for S-04). It went hard for three days and then really slowed, but did keep fermenting. I used one packet in 17litres having mashed at 67oC.

Not really sure what to recommend - I'm pretty new to brewing!

Have you tried raising the temperature a bit? Also, did you oxygenate well at the beginning?

being at constant 20degC, and stirred it well. my attenuation so far works out at about 72% so if what im reading is correct that is getting to the max for S-04, so don't wether to transfer to clean vessel and pitch another packet of yeast or should I leave it a while longer as it has only being 4 days,

rodabod · Sep 4, 2015

I would say that's a reasonable amount of attennuation. Mine didn't manage much more than 60% in the end, but I mashed at 70c. Try and monitor for slow airlock activity, or even smell the top of the airlock to see if it's bubbled recently. Mine ended with a very long, slow fermentation at 20c.

S-04 attenuation vs mash temp

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