vortura
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- Joined
- Feb 18, 2014
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Hi all,
I had a go at brewing my first stout on Saturday, the fifth batch I've done in all, and the first time I've had what seems to be a stuck fermentation. I sprinkled a whole pack of Mangrove Jack M42 into 10L of wort at 16C/61F at 8PM on Saturday, and placed the fermenter inside my temperature controlled fridge, set to 19C/66F. OG was 1.048 measured with a hydrometer and the wort was aerated before pitching by giving the fermenter a good shake. I checked it at 3PM on Sunday, and the airlock was bubbling away nicely.
Sunday was fathers day here, and lucky me, the kids got me a Tilt hydrometer. Monday evening, I sanitised it, and dumped it in the wort, which came back with a reading of 1.020, so everything seemed to be well on track. Tuesday morning though, it was still sitting on 1.020, so I suspected the fermentation might have slowed up or stalled. The airlock had stopped bubbling at this point, but from the gunk on the walls of the fermenter, it seemed like there had been a reasonable amount of krausen at least. I bumped the temperature up to 21C/70F, gently swirled the fermenter hoping to agitate the yeast, and headed off to work
Tuesday evening, however, and it's still firmly stuck on 1.020. I wondered if it might be a problem with the Tilt, so I took a sample and checked it with the hydrometer, which showed more like 1.022 - a discrepancy, but not in the direction I was hoping. To be honest, the sample tastes great, so it's not a disaster by any stretch. 1.048 -> 1.022 is about 3.4% ABV, so that's okay, even if the body and bitterness might be a bit off.
What I'm wondering though is, what I can learn from this episode, and what to do next, if anything. I guess the obvious answer is to leave it and see what happens, but I was also considering the option of pitching more yeast. Is there any rush to do that, or could I leave it a week or so and then decide? I was planning on fermenting for about 14 days anyway.
The grain bill was:
63% Gladfield Pilsner
13% Gladfield Supernova
9% Gladfield Brown
7% Lactose Sugar
4% Gladfield Light Chocolate
3% Bairds Black
1% Gladfield Roast Barley
I was wondering about the possibility of unfermented sugars inflating the OG but limiting the FG. Is there anything in that grain bill to suggest this could have been a factor? I mashed at 68C/154F for 60 minutes, with a 75C/167F mash out for 10 minutes. I use a grainfather, so I think those temps should be reasonably accurate.
Any thoughts or advice would be appreciated.
Cheers!
I had a go at brewing my first stout on Saturday, the fifth batch I've done in all, and the first time I've had what seems to be a stuck fermentation. I sprinkled a whole pack of Mangrove Jack M42 into 10L of wort at 16C/61F at 8PM on Saturday, and placed the fermenter inside my temperature controlled fridge, set to 19C/66F. OG was 1.048 measured with a hydrometer and the wort was aerated before pitching by giving the fermenter a good shake. I checked it at 3PM on Sunday, and the airlock was bubbling away nicely.
Sunday was fathers day here, and lucky me, the kids got me a Tilt hydrometer. Monday evening, I sanitised it, and dumped it in the wort, which came back with a reading of 1.020, so everything seemed to be well on track. Tuesday morning though, it was still sitting on 1.020, so I suspected the fermentation might have slowed up or stalled. The airlock had stopped bubbling at this point, but from the gunk on the walls of the fermenter, it seemed like there had been a reasonable amount of krausen at least. I bumped the temperature up to 21C/70F, gently swirled the fermenter hoping to agitate the yeast, and headed off to work
Tuesday evening, however, and it's still firmly stuck on 1.020. I wondered if it might be a problem with the Tilt, so I took a sample and checked it with the hydrometer, which showed more like 1.022 - a discrepancy, but not in the direction I was hoping. To be honest, the sample tastes great, so it's not a disaster by any stretch. 1.048 -> 1.022 is about 3.4% ABV, so that's okay, even if the body and bitterness might be a bit off.
What I'm wondering though is, what I can learn from this episode, and what to do next, if anything. I guess the obvious answer is to leave it and see what happens, but I was also considering the option of pitching more yeast. Is there any rush to do that, or could I leave it a week or so and then decide? I was planning on fermenting for about 14 days anyway.
The grain bill was:
63% Gladfield Pilsner
13% Gladfield Supernova
9% Gladfield Brown
7% Lactose Sugar
4% Gladfield Light Chocolate
3% Bairds Black
1% Gladfield Roast Barley
I was wondering about the possibility of unfermented sugars inflating the OG but limiting the FG. Is there anything in that grain bill to suggest this could have been a factor? I mashed at 68C/154F for 60 minutes, with a 75C/167F mash out for 10 minutes. I use a grainfather, so I think those temps should be reasonably accurate.
Any thoughts or advice would be appreciated.
Cheers!