How did I break my oat stout-like beer?

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bruce_the_loon

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Okay, so first time using oat malts in a beer, heading for something resembling a stout with stuff I had laying around. I've either buggered up somewhere in the process or the yeasties have stalled.

Recipe as follows.

7.11 lbs Chateau Pale Ale malt
1.10 lbs Chateau Oat malt
1.10 lbs Thomas Fawcett 60L Crystal Malt
1.2. lbs Chateau Peated malt
1.7 lbs Best Chocolate Malt
0.5 oz Southern Promise - 10.8% alpha - 60 minutes
0.2 oz Apollo - 18% alpha 60 minutes (to empty the bag)
1 oz EKG at 10 minutes.

Hops flavour and bittering is fine. Problem seems to lay with the fermantability of the wort. BeerSmith3 estimated FG at 1.017.

Process as follows, using the full body BIAB profile in BeerSmith3 (possible problem 1).
  • Treated 9.7 gal with a campden tablet (possible problem 2) overnight and then heated to 161.6F, mashed in and got 156F.
  • Mashed for 60 minutes and final temp was 153F.
  • Drained and squeezed the bag and hit 1.044 SG (predicted 1.045) with 8.89 gal remaining.
  • Did a 90 minute boil and ended up with 6.6 gal going into the fermenter at 1.054. I was happy with the numbers.
  • Pitched a packet of SafAle S-04 at 72F and set the fermentation chamber to 66F.
  • Yeast took off nicely and raced from 1.054 on the Tilt down to 1.025 from the 27th to the 29th and has stalled there since. Confirmed with a hydrometer.
  • The dregs fermentation, about 1.5l in a 2l PET soda bottle which I do for funsies, has reached around 1.028.
Now, did I bugger up with using a full body mashing profile with oat malt; did BeerSmith3 get the estimates wrong; is the campden tablet killing off the yeasties or am I just being impatient with this yeast?
 

TheMadKing

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Okay, so first time using oat malts in a beer, heading for something resembling a stout with stuff I had laying around. I've either buggered up somewhere in the process or the yeasties have stalled.

Recipe as follows.

7.11 lbs Chateau Pale Ale malt
1.10 lbs Chateau Oat malt
1.10 lbs Thomas Fawcett 60L Crystal Malt
1.2. lbs Chateau Peated malt
1.7 lbs Best Chocolate Malt
0.5 oz Southern Promise - 10.8% alpha - 60 minutes
0.2 oz Apollo - 18% alpha 60 minutes (to empty the bag)
1 oz EKG at 10 minutes.

Hops flavour and bittering is fine. Problem seems to lay with the fermantability of the wort. BeerSmith3 estimated FG at 1.017.

Process as follows, using the full body BIAB profile in BeerSmith3 (possible problem 1).
  • Treated 9.7 gal with a campden tablet (possible problem 2) overnight and then heated to 161.6F, mashed in and got 156F.
  • Mashed for 60 minutes and final temp was 153F.
  • Drained and squeezed the bag and hit 1.044 SG (predicted 1.045) with 8.89 gal remaining.
  • Did a 90 minute boil and ended up with 6.6 gal going into the fermenter at 1.054. I was happy with the numbers.
  • Pitched a packet of SafAle S-04 at 72F and set the fermentation chamber to 66F.
  • Yeast took off nicely and raced from 1.054 on the Tilt down to 1.025 from the 27th to the 29th and has stalled there since. Confirmed with a hydrometer.
  • The dregs fermentation, about 1.5l in a 2l PET soda bottle which I do for funsies, has reached around 1.028.
Now, did I bugger up with using a full body mashing profile with oat malt; did BeerSmith3 get the estimates wrong; is the campden tablet killing off the yeasties or am I just being impatient with this yeast?

Which campden tablet did you use?

I believe they make a whole tablet suitable for 5 gallon batches, but the standard variety are dosed such that a whole tablet is intended to treat 20 gallons, so you need less than half of one to treat your water. That could indeed be the source of your issue
 
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bruce_the_loon

bruce_the_loon

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Which campden tablet did you use?

I believe they make a whole tablet suitable for 5 gallon batches, but the standard variety are dosed such that a whole tablet is intended to treat 20 gallons, so you need less than half of one to treat your water. That could indeed be the source of your issue
LHBS repackaged without detailed labeling. Site does say equivalent to 420mg sodium metabisulfite which looks to be the standard ones. So I guess I did O/D the campden tablet.

Just read a couple of sites on the net that say that it won't kill the fermentation, only stall it for a while until the yeasties recover from being stunned. Should I just wait a while or over-build a starter and repitch with a lot of wide-awake yeast cells?

Source: Campden Tablets: What Are They, Uses & How They Work
 

CascadesBrewer

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I am curious about how strong of a peated flavor this malt has...that seems like a lot: 1.2. lbs Chateau Peated malt

Adding 1 campden tablet pre boil will not impact your fermentation. The tablets are formulated to add 1 tablet per gallon for stalling fermentation.

Assuming your 156F mash start temp is accurate, it is a bit high but I would expect a lower final gravity. On the other hand, if it was actually up above 160F, then fermentability can start to take a dive.
 
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bruce_the_loon

bruce_the_loon

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So, follow-up with sad news. The stout is no more, it is a former stout, it is pining for the canals, etc etc.

So after leaving it in the fermenter at 66F for another 16 days with a re-pitch at 4 days after my last post, the Tilt still reported the same gravity. So we decided to bottle as nothing more was happening.

Carbonation at 10 days post bottling was acceptable, then we cracked a couple of minor gushers at 17 days post bottling. Testing gravity on one of the gushers gave a 1.021 reading. The remaining bottles were degassed and recapped. The stout tasted fine, no off flavours, souring or indications of most infections.

Fast-forward to about three days ago, we fast-chilled a couple of bottles as a test and they gushed again, but still drinkable. Carbonation had returned with a passion. We figured maybe the fast-chilling didn't allow the CO2 to dissolve back into the beer. So some were chilled for three days in the fridge and tested today. Carbonation levels were still way to high, so the decision was taken to dump the batch because serving them was unmanageable. Careful decapping at room temperatures yielded fire hose behaviour down from the caps with a couple of loud pops where the partial release of the caps went all the way.

Forgot to grab a sample for gravity testing in the excitement, but the beer still tasted normal. No souring or other indicators of infection. I'm thinking that the warm weather that occurred here (up to the mid 80s) after the bottling along with sufficient time woke the yeast up again and it continued fermenting in the bottles. Either that or I picked up some infection that didn't leave off-flavours during bottling. The citra smash I did after this is perfectly fine.

I probably should have attempted a warming while it was in primary, but the fermentation chamber only had chilling capability at the time and ambient was in the 66F-68F range. I've since obtained a suitable heating pad to allow for lifting of the temps.

Any other ideas?
 

cire

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Quite difficult to know the precise cause of that outcome, so can only offer some suggestions.

Your mash was for 60 minutes, but I will mash dark beers with large proportions of unmalted grains for 90 minutes, aiming to ensure total conversion. That may not be the cause in this case, but it is worth bearing in mind for the future.

The time needed to convert starches to sugars is not fixed, depending upon both the quantity of enzymes and how active they are. for the duration Those enzymes denature with time and the higher the temperature, the quicker they degrade, so your higher mash temperature might not have helped in this case. Calcium added to the brewing liquor lengthens the endurance of these enzymes in a hot mash while lowering pH, combining with phosphates to deposit, but some do remain to give protection. However, a low pH in the mash limits enzyme activity such that a pH lower than 5.0 causes conversion to take more than 60 minutes. To overcome this with enough calcium present to protect enzymes, mash liquor needs an appropriate level of alkalinity for all darker beers.

With 2.8lbs of roast and crystal malts in a little over 12 lb mash for a stout, it may be necessary to have something like 100 ppm calcium and 75 ppm alkalinity as CaCO3 to achieve a fully fermentable wort.

66F is a fine temperature to start fermentation, but to get some character and full fermentation it is wise to let, or help, it rise to over 70F and it should complete fermentation inside a week and be ready to bottle shortly afterwards without fear of gushing.
 
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Okay, so first time using oat malts in a beer, heading for something resembling a stout with stuff I had laying around. I've either buggered up somewhere in the process or the yeasties have stalled.

Recipe as follows.

7.11 lbs Chateau Pale Ale malt
1.10 lbs Chateau Oat malt
1.10 lbs Thomas Fawcett 60L Crystal Malt
1.2. lbs Chateau Peated malt
1.7 lbs Best Chocolate Malt
0.5 oz Southern Promise - 10.8% alpha - 60 minutes
0.2 oz Apollo - 18% alpha 60 minutes (to empty the bag)
1 oz EKG at 10 minutes.

Hops flavour and bittering is fine. Problem seems to lay with the fermantability of the wort. BeerSmith3 estimated FG at 1.017.

Process as follows, using the full body BIAB profile in BeerSmith3 (possible problem 1).
  • Treated 9.7 gal with a campden tablet (possible problem 2) overnight and then heated to 161.6F, mashed in and got 156F.
  • Mashed for 60 minutes and final temp was 153F.
  • Drained and squeezed the bag and hit 1.044 SG (predicted 1.045) with 8.89 gal remaining.
  • Did a 90 minute boil and ended up with 6.6 gal going into the fermenter at 1.054. I was happy with the numbers.
  • Pitched a packet of SafAle S-04 at 72F and set the fermentation chamber to 66F.
  • Yeast took off nicely and raced from 1.054 on the Tilt down to 1.025 from the 27th to the 29th and has stalled there since. Confirmed with a hydrometer.
  • The dregs fermentation, about 1.5l in a 2l PET soda bottle which I do for funsies, has reached around 1.028.
Now, did I bugger up with using a full body mashing profile with oat malt; did BeerSmith3 get the estimates wrong; is the campden tablet killing off the yeasties or am I just being impatient with this yeast?

Two thoughts:

  1. In a thread like this, lead with the problem. Throw all the data after. Quite a commitment for somebody to get to the point here.
  2. I've had the same issue with an oatmeal stout. I think I mashed high, but not sure. Fix was simple.

 

AlexKay

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Probably not relevant to your problem, but if you didn’t mill the oats yourself, and really crank down the mill gap, they’re almost certainly not going to be suitably crushed. FYI for next batch. If you don’t have a mill, flaked oats.
 

Brewdog80

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Temp was fine to start, but it was reduced too low. should have tried going back to 70f.
 

Oldskewl

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Have you brewed any Saisions or used any yeasts with the STA-1 gene? I fought this issue for a several batches. Beers would ferment out ok and hold steady for days or weeks. Then I would bottle and that tiny amount of STA-1 yeast would multiply and ferment my stouts and porters down to 1.010-1.014. Ended up with gushers and dry stouts. But the beers tasted fine. If you cracked a beer in the first month or 2 things were fine and the FG was still in the 1.020-1.024 range. But with time they would continue to ferment. I ended up cleaning everything with a mild bleach solution and it finally killed it. All is good now, but I always do a mild bleach soak after I brew a Saison.
 

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