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Old 07-13-2009, 09:12 PM   #1
KYB
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Default Very Low Attenuation - What to Do

I searched some but still don't know what I should do.

So I brewed my modified Foreign Extra Stout. I used White Labs Irish Ale yeast (with a 1000ml starter using 2 cups DME 24hrs prior) and mashed at 156. Was that too high of a mash temp? I did the same for the old recipe that turned out awesome. I'm thinking it might have fermented too hot. It was in the basement, but at like 73 degrees on the outside of the fermenter. Our AC has been broke, now it's 68, although ambient feels cooler. I don't have any freezer room to make a swamp cooler, although I will soon. I'm thinking that may have been it. It has been in Primary for 4 weeks. OG of 1.071, FG of 1.031.

Should I pitch more yeast or just bite the bullet and bottle it. Similar thing happened with my Dry Stout. I should really start checking my beer earlier. Thanks.

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Old 07-13-2009, 10:21 PM   #2
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Although 156F isn't too high if your goal is a very malty beer, it is probably a large part of your problem. What percentage of the recipe was unfermentables?

Dry stouts should be mashed around 150F.

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Old 07-13-2009, 10:24 PM   #3
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Also, when's the last time you calibrated that thermometer? 156F isnt' bad, unless your thermo's reading a few degrees lower than reality.

higher fermentation temps shouldn't leave you under-attenuated.

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Old 07-13-2009, 10:32 PM   #4
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Unfermentable sugars would be my first guess.

I would first try swirling your fermenter to rouse the yeast back into suspension, if that fails to restart the fermentation get some yeast nutrient/energizer, add the recommended amount and give it a gentle stir with a sanitized spoon.

When all else fails pitch more yeast.

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Old 07-13-2009, 10:50 PM   #5
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Thanks. Maybe I'll try some yeast nutrient - didn't think about or read about that. At least the sample tasted pretty good. I guess I'll pitch more yeast if that doesn't work, although it won't be Irish Ale, it would have to be Dry Yeast as that is all I can get in Lexington.

Here is the recipe:

Code:
Recipe Specifications
--------------------------
Batch Size: 5.00 gal      
Boil Size: 6.41 gal
Estimated OG: 1.071 SG
Estimated Color: 37.4 SRM
Estimated IBU: 68.8 IBU
Brewhouse Efficiency: 72.70 %
Boil Time: 60 Minutes

Ingredients:
------------
Amount        Item                                      Type         % or IBU      
7.50 lb       Pale Malt, Maris Otter (3.0 SRM)          Grain        54.55 %       
2.50 lb       Barley, Flaked (1.7 SRM)                  Grain        18.18 %       
1.00 lb       Cara-Pils/Dextrine (2.0 SRM)              Grain        7.27 %        
1.00 lb       Oats, Flaked (1.0 SRM)                    Grain        7.27 %        
0.75 lb       Black (Patent) Malt (500.0 SRM)           Grain        5.45 %        
0.50 lb       Caramel/Crystal Malt - 60L (60.0 SRM)     Grain        3.64 %        
0.25 lb       Chocolate Malt (450.0 SRM)                Grain        1.82 %        
0.25 lb       Wheat, Flaked (1.6 SRM)                   Grain        1.82 %        
1.00 oz       Challenger [7.50 %]  (60 min)             Hops         23.4 IBU      
2.00 oz       Goldings, East Kent [5.00 %]  (40 min)    Hops         27.4 IBU      
1.00 oz       Challenger [7.50 %]  (30 min)             Hops         18.0 IBU      
1 Pkgs        Irish Ale (White Labs #WLP004) [Starter 10Yeast-Ale
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Old 07-14-2009, 01:08 AM   #6
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Did you do an iodine test to see if conversion was complete?
You have 3.75# unmalted grain to 7.5# Marris Otter.
There might not have been enough diastatic power to convert all that starch.
Or it may have been this in combination with the high mash temp.

Also, 2 cups of DME in a 1 liter starter seems like a lot.
The yeast are happiest at around 1.040 and need lots of oxygen to reproduce.

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Old 07-14-2009, 01:33 AM   #7
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Quote:
Originally Posted by HairyDogBrewing View Post
Did you do an iodine test to see if conversion was complete?
You have 3.75# unmalted grain to 7.5# Marris Otter.
There might not have been enough diastatic power to convert all that starch.
Or it may have been this in combination with the high mash temp.

Also, 2 cups of DME in a 1 liter starter seems like a lot.
The yeast are happiest at around 1.040 and need lots of oxygen to reproduce.
No I didn't do an iodine test. My first FES had the same amount of grains and unmalted to malted ratio and finished at 1.020, mashing at 156. I'm using a digital Taylor thermometer, but haven't done any calibrating.

Actually come to think of it, it might have been 1 cup. I was reading the starter info on Mr. Malty before I did it, but I forget. I pretty much did what that site said.

I added some yeast nutrient, so we'll see what happens.
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