Viscous Oatmeal Stout

This past weekend I set out recycle my Safale S-04 from the previous batch that was ready to keg (Amarillo Coffee Blonde) and settled on using some of the yeast slurry to make an Oatmeal Stout. I’d never used oats as a large portion of the grain bill and most recipes seem to use 2-10% but I really wanted to push the limits and get a nice, heavy, oat-y stout from this. So I did a bit of reading on the style and took a look at a few recipes and eventually came up a recipe that was ~18% oat:

Recipe Specifications
Boil Size: 7.44 gal
Post Boil Volume: 6.24 gal
Batch Size (fermenter): 5.50 gal   
Bottling Volume: 5.00 gal
Estimated OG: 1.065 SG
Estimated Color: 40.6 SRM
Estimated IBU: 33.9 IBUs
Brewhouse Efficiency: 72.00 %
Est Mash Efficiency: 78.5 %
Boil Time: 60 Minutes

Amt                   Name                                     Type          #        %/IBU         
8 lbs                 Pale Malt, Maris Otter (3.0 SRM)         Grain         1        57.1 %        
2 lbs 8.0 oz          Oats, Flaked (1.0 SRM)                   Grain         2        17.9 %        
1 lbs                 Chocolate Malt (350.0 SRM)               Grain         3        7.1 %         
1 lbs                 Roasted Barley (300.0 SRM)               Grain         4        7.1 %         
1 lbs                 Victory Malt (25.0 SRM)                  Grain         5        7.1 %         
8.0 oz                Caramel/Crystal Malt - 80L (80.0 SRM)    Grain         6        3.6 %         
2.00 oz               Willamette [5.50 %] - Boil 60.0 min      Hop           7        33.9 IBUs     
120 mL slurry         SafAle English Ale (DCL/Fermentis #S-04) Yeast         8        -             

Mash Schedule: Single Infusion, Light Body, No Mash Out
Total Grain Weight: 14 lbs
Name                   Description                                              Step Temperat Step Time     
Mash In                Add 24.50 qt of water at 168.3 F                         156.0 F       60 min        

Sparge: Fly sparge with 2.19 gal water at 168.0 F

My efficiency was a little low, but otherwise the brewing went well, yielding an oily-black sweet wort. Interestingly, I got a bit of wort on my hands and it is extremely viscous; I can tell that there was a large portion of oats used just by feeling the wort. After a bit of fooling around with the MrMalty yeast calculator I settled on pitching 120mL of the thick S-04 slurry, just to be on the safe side. The beer started visibly fermenting 6h after pitching – it’s been going for 2 days now. Planning on letting this sit for a few weeks and then kegging. I’ve been planning on a coffee stout for a while – if this turns out well, I’ll likely brew it again, adding some coffee after fermentation!

Update: Kegged and burst carbing @ 30psi 12/17/14.


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