Public Brew: OatMilk Stout

We had a fun homebrew session the other day with Bryce Dwyer from Bad At Sports.  Bryce is currently working on a series highlighting artists who are working with beer as an artistic material.  We will post Bryce’s article when he releases it next week.  I’ll try to keep the recipe as simple as possible for quick reference and accessibility.  Feel free to question/comment.

OatMilk Stout Recipe:

This is an all-grain recipe which factors a low-end mash efficiency of 65%.  Please keep this in mind if you are to use this recipe on a higher efficiency system (as most will).  5.5 gallon final volume.

Grain Bill:

  • Marris Otter  11.28#
  • Roast Barley    1.88#
  • Oats (Quick)    1.07#
  • Black Malt          .56#


  • 1.64 oz Fuggle Hops @ 45 min boil time (5.3% AA)

Other Additions:

  • Whirlfloc Tablet @ 10 min boil time
  • Lactose (1 lb) @ 10 min boil time


  • 152º Single temperature infusion mash (pH 5.2) for 60 mins (tincture test)


  • Wyeast Irish Ale XL (1084)


Target OG: 1.060
Target IBU: 30 


For this week, what happens when you miss your Target Gravity when homebrewing?

Hitting target gravities consistently help you refine your recipes and become a better brewer.  The more consistent you are in your process, the easier it will be to manipulate recipes and discover what is and isn’t working in each batch of beer.  As home brewers, efficiency can sometimes be an issue based on multiple factors. 

According to Ray Daniels’ “Designing Great Beers” there are a few easy tips to get you to where you need to be with your target gravities.  I also use the formulas from Daniels’ text as well below.

If the gravity is lower than expected:

  • Boil your wort longer to produce a lower volume, higher gravity, wort
  • Add sufficient malt extract

If the gravity is higher than expected:

  • Produce a higher volume of beer to lower your gravity and hit your target.
  • Remove a portion of the wort from the boil pot and use it for  another purpose

If you are familiar with using Gravity Units (GU), figuring out how to compensate for a low gravity is relatively easy.  If adding dry extract, you will be adding roughly 45 GU per pound.  If adding a liquid, you can predict 38 GU per pound.  I prefer the dry extract as I prefer the consistency when stored for longer periods and it tends not to impart as much coloration as the liquid extract will.  Experiment for yourself to find your own personal preference.

So let’s say I miss my target gravity and the wort from my mash has a lower gravity.  We need to figure out how much extract to add (and quickly as we don’t want to waste much time on math while brewing). Formula as followed:

Extract (lbs.) = [(Target GU x Target vol.) - (GU x Vol.)from mash] / Extract/lb. value

Let’s use the MilkOat recipe as an example.  Say I want to hit 1.060 for my OG (5.5 gal batch = 330 GU).  I usually need at least 6 gallons from the mash for a 1 hour boil on the stovetop as i’ll lose about 1/2 gallon to evaporation.  After the mash, I am left with 6 gallons of wort at 1.050 (using temperature correction with my hydrometer reading).  How much extract should I add to get my gravity where I want it? Just plug and play using the recipe above:

Extract Needed = [(330 GU)-(300 GU)]/45GU (figure for dry extract, use 38 for liquid)
= .67 lbs  

As your wort heats up to boil, you should have plenty of time to figure out these figures and add to your wort before boiling begins.  Its always hand too keep a couple pounds of dry extract around, even if you want to focus on all grain.  Sometimes we don’t hit perfection, but should be as consistent as we can to become better brewers.

  1. arcadebrewery posted this
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