Smoked Porter - Stuck fermentation or just impatient?

[playoldgame]

I've had a couple of goes at brewing a small batch of smoked porter using a recipe I put together myself, which has an OG of 1.050. Both times, fermentation appears to have stopped, and the gravity has stuck around the 1.030 mark.

I originally pitched half a pack of Safale S04, and had a good initial fermentation before it went dormant. There's no sign of infection, I've tried swirling it and warming it up a bit (no reaction), repitching fresh yeast (no reaction except now I've got a yeast cake in the secondary!), and all the other stuff that gets recommended, and it just won't kick off again - the gravity has stayed at 1.030.

I threw out the first batch after giving up on it after about 3 weeks (which I now know was a silly thing to do, as there wasn't anything really wrong with it), but I've got the second batch sitting around after only two weeks - but it looks just as dead as the first batch did.

Here's my grain bill (Total: 905g):

Pale Malt: 500g (55%)
Rauch Malt: 225g (25%)
Chocolate: 67.5g (7.5%)
Crystal: 67.5g (5.7%)
Black: 45g (5%)

Mashed with 2.2l water

Sparged with 3.8 litres of water, 1 hour boil with EKG hops in there for 40 minutes.

Fresh Blackberries added to secondary - Blackberry Smoke, y'see.

Is there anything obvious that I've missed, aside from just not giving it enough time to come back to life?

 

[McMullan]

That looks like a really nice recipe. What temperature was the mash and for how long? Did you rehydrate the yeast? Did you aerate the wort prior to pitching? What was your ambient fermentation temperature, roughly?

 

[playoldgame]

That looks like a really nice recipe. What temperature was the mash and for how long? Did you rehydrate the yeast? Did you aerate the wort prior to pitching? What was your ambient fermentation temperature, roughly?

Let's see...

First off, thanks!

Kept the mash between 63c and 68c.
Pitched dry, then gave the fermenter a vigorous shake to wet the yeast and aerate - I figured around 5-6g at this volume would be okay to pitch dry.

Ambient temperature is between 18c and 21c, but I've got a heat mat that I used to try to give it a bump when I repitched. That kept the thermometer on the fermenter around 28c - a bit higher than recommended, but thought it was worth a shot to get it going.

 

[McMullan]

Can't see where it might be going wrong, TBH. Dodgy batch of yeast? Maybe rehydrate the yeast next time? Did you add blackberries to the first batch too? I'm wondering whether they've had an impact. Any means to measure the pH of your beer? The blackberries might have caused the pH to change from what yeast prefer, causing them to drop out?

 

[playoldgame]

First time, I made a syrup with fresh blackberries and sugar, and added that at the end of the boil, right before I started cooling. Second time, I just added the whole fruit to secondary. No litmus paper or anything, I'm afraid.

Might try Nottingham or Wyeast London III if I give this another go...

 

[playoldgame]

As I'm brewing a small batch of Irish red ale with blueberry today and using Nottingham yeast, thought I'd throw some into the porter as a last roll of the dice. I'll report back :)

 

[playoldgame]

The Nottingham Yeast didn't work either - brew was still dead, so another batch got tossed out.

I can only think that it is the blackberry acid killing the yeast off prematurely. If I try this again, I'll wait for fermentation to completely finish, then rack onto blackberries for a while before bottling.

 

[McMullan]

Have a read of this.

http://byo.com/hops/item/679-fruit-brew-part-2-techniques

I did a nice raspberry stout. I used WLP005 and racked on top of a pack of Funkin raspberry puree after a week and left it there for 10 days. Steep the dark malts separately and add to the 'coffee' to the boil. Pretty sure you can get Funkin black berry puree on amazon.

 

[playoldgame]

That's an excellent read - thanks very much :thumb: