Stuck Fermentation

[Crusader-Rob]

Smoked Porter. stuck fermentation at 1.028, I'm pretty annoyed.

I used S-04 formain yeast in a 11litre batch, 1 rehydrated packet.

I've roused and shaken the living hell out of it, and I ended up pitching a small starter of Us-05, which still hasn't moved it, been in for about a week and a half. raised temp to 24, to get things moving too.

OG 1.060

Current gravity 1.028

recipe as follows:

1kg maris otter

1kg weyermann smoked

0.2kg crystal medium

0.15kg pale chocolate

0.05kg black

0.15 torrified wheat

0.5kg brown malt

mash 60 mins at 70ish, Poor insulation ended at 63 degrees

small sparge step of 6 litres ad 76 degrees.

Any ideas on possible causes, and possible fixes, I'm so disappointed as it was going to be a competition beer, and it currently tastes awesome, but is still quite sweet, There ended up being a little about 1.5 litres of trub from the kettle, that hops and break material, which is high.

I also used a relatively coarse grain bag BIAB. I've since got a new one, which is much finer than this one.

I would prefer not to throw any sugar at it if possible, but its looking that way. What about Candi syrup/sugar? would this make any difference? otherwise dextrose is the one i'll be chucking in?!

[Ralph]

Looks like about 30% specialty malt. Did you put this in some brewing software that would predict what FG you should get?

Also, did you mash with all of the dark grains in for the full mash time? That many dark malts may have dropped the pH quite a bit leading to the enzymes not working as efficiently as possible... combined with the temperature maybe being a bit low it could be possible that the starch was not fully converted to sugar in the mash? If there is still starch then the brew may not drop in gravity from where it is?

Other than that I think S04 may have a reputation for stopping before it should? Pitching a starter of something like US05 should have fixed this problem though?

[John H]

I've had a few like this in the past. As already mentioned you can rebrew with a low mash temp and blend or add dextrose to give further apparent attenuation.

[Crusader-Rob]

Isn't it more like 20% specialty malts?? Isn't Brown considered a base malt? the FG from Beer smith says it should reach 1.018, so I was expecting 1.020 most likely, given the higher temp and the crappy S-04.

I mashed for 60mins, 30mins for the pale chocolate, and 15mins for the Black Malt.

If I made the recipe again, using that general b\malt bill, how would you make it up for a robust smoked porter?

What about some dark Invert sugar? Or some Brown sugar? and how much for an 11litre batch?

[Ralph]

Ah! I have not used brown... did not realise it needed to be mashed and not just steeped. I have no idea if the "browning" process added more unfermentables or not tho? Yup 1.020 or so sounds like a reasonable place to aim for.

[Ralph]

You could always try throwing some 3711 in there to see if it will chew through some more? 3711 seems to have great attenuation!

[Crusader-Rob]

HA! Yeah I thought about that. I thought of Sandiego Super Yeast, thats supposed to be pretty good??

[Ralph]

I have some San Diego, but I doubt it would go much lower than 05. It just seems to ferment really quickly

[Tom C]

Brown malt is very un-fermentable in my experience - handy for adding body to ordinary bitters but too much leaves you with a sweet treacle of a beer.

With no evidence to back it up, I'd suspect the smoked malt to be high in unfermentables too.  You'd need to check Weyermanns spec though rather than trust my hunch.

My favourite plan for dealing with 'surprises' like this is to brew a light bodied, high IBU, highly carbonated beer and blend the two in the glass to make an acceptable drink!

[Karl Hayes]

Sounds like a job for Denny's Favourite 50

[Ralph]

Rob, I have some Dennys if you wanted to try it too, although I never found that it attenuated that much. I also have some 1272 that I just started up... and the San Diego is starting up at the moment for a brew, but we could easily make another starter from it.

[Dougal]

3711 will work, but you'd definitely get flavour contributions that probably aren't what you're looking for. If I were you I'd repitch a large amount of active, fresh slurry of US-05, or Zane's San Diego. Even with the crystal and mashed at 70C it surely won't be that un-fermentable that you can't get down to 1.018.

My dubbel that stuck at 1.020 was mashed for a decent while at 73C (by accident!). I managed to bring it down to 1.009 using a fresh 4L starter of 3711, and got a bronze at the NHC for it.

[Grant R Baker]

I would syphon this off to another vessel and maybe top up with a sprinkle of S04.

The only malt I would question really is the amount of Smoked malt.. I have no idea how much % fermentables come out of that one.... but I have made beers with higher percentages of roasted malts before.. the last one went from 1.068 to 1.012 but it was using a yeast meant for higher alcohol levels.

It is possible that your yeast died... but I have never had that happen yet.