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Oatmeal Stout (Partial Mash)

Lynnae Endersby oatmeal stout winter

Oatmeal Stout

Boil duration: 1 hour
Final volume: 20 Liters
Original/starting gravity: 1.052
Final gravity: 1.014
Alcohol: 5.03%

Ingredients needed

200 g Pale Malt
300 g Pale Crystal
160 g Oat malt
200 g Brown Malt
200 g Roasted Barley Malt
300 g Chocolate Malt
1 kg Dry Malt Extract
2.8 kg Light Liquid Malt Extract
10 g Southern passion (US4/78) hops (60 min)
28 East Kent Goldings hops (
5 ml Irish Moss
Fermentis Safale US-04
120 g Sucrose (to carbonate)

Water needed:
5 Liters @ 70 C to soak grain in (referred to as mashing)

6 Liters @ 77 C to rinse grain (referred to as sparging)

Work Order

  1. Measure out 5 Liters of water into a pot and heat to 70 C°.
  2. Fill grain bag with the crushed grain.
  3. Gently lower the grain bag into the warm water (gas/heat should be switched off).
  4. Stir the grain gently inside the grain bag to make sure the entire contents of the bag is in contact with the warm water.
  5. The temperature of the water should now be 68 C°. If the water is too cold apply some heat.
  6. When the temperature is stable at 68 C° cover the pot with a blanket and set a timer for 60 minutes. (You are now mashing).
  7. Measure out 6 liters of water into a second pot and cover with a lid (this will be sparge water to rinse the grain with after an hour). Start heating gently to 77 C°.
  8. After 45 minutes check that the sparge water temperature is 77 C° (adjust temperature if necessary). 
  9. Once the hour ‘mash’ is finished lift the grain bag out of the pot and let it rest in a sieve or colander (to drain into the pot it soaked in)
  10. Gently rinse the grain bag with the 77 C° sparge water making sure to leave about 7 cm headroom in the pot.  
  11. Apply heat to the collected grain liquid (now called wort) while sparging. Discard grain once sparging is complete.
  12. Once the wort almost comes to a boil remove from the heat and add the liquid and dry malt extract powder. Stir gently to dissolve and return to the heat.
  13. When the wort has come back to a boil add the first hop addition of 10 g of Southern Passion. Set the timer for 60 minutes.
  14. Stay with the pot for at least 5 minutes making sure the wort does not boil over. (if it looks like a boil over might happen turn off the heat and bring back to the boil slowly).
  15. While the wort boils make a sanitising solution. This can be made with 4 millilitres of unscented bleach for every liter of water. (Follow the instructions of a no rinse sanitiser if using one).
  16. Soak fermenter and all the equipment that will come in contact with the beer in the solution for at least 30 minutes. Rinse off the bleach solution with cold water at least 3 times making sure there is no bleach residue left.  Once the fermenter is santised pour the sanitising liquid into a suitable container to sanitise glass jug, scissors etc for later use.
  17. After the wort has boiled for 45 minutes - add the second hop addition (20 g East Kent Goldings), lower the immersion chiller into the pot (if using one) and add the sachet of Irish moss.
  18. When there is five minutes left to the boil add the last hop addition (8 g East Kent Goldings).
  19. Sanitise the thermometer, funnel (if using), sieve and a plastic/metal spoon.
  20. When the wort has boiled for one hour and all the hop additions have been added the wort needs to be chilled.
  21. Put a lid on the pot (to keep any wild yeasts/bacteria from infecting the wort while cooling) and leave in an ice bath to cool down. Alternatively the immersion chiller can be connected).
  22. Pour 5 liters of cold water into the sanitised fermenter while the wort cools.
  23. Rehydrate the sachet of yeast (remember to open with a pair of sanitised scissors) in the glass measuring jug containing 120 ml of clean tepid water. Cover with cling film and set aside.  
  24. When the wort has cooled to 35 C° remove the pot from the ice/immersion chiller from the pot.
  25. Pour the wort through a sanitised sieve into the fermenter filled with 5 liters of cold water – you can scrape the sieve with the sanitised spoon to speed up the process.
  26. Top off the fermenter to the 20 liter mark and take a hydrometer reading.
  27. Shake up the fermenter to aerate the wort for 2 minutes.
  28. Swirl up the yeast and add to the fermenter.  Shake the fermenter well for another 2 minutes.
  29. Fit the airlock filled with water or vodka and leave to ferment between 18 – 24 C° for two weeks.

Carbonating your beer after 2 weeks :

  1. Firstly you will need to make a sanitising solution again with either unscented bleach or a no rinse sanitiser to sanitise your bottles, caps, bottling tube an a spoon.
  2. Measure out 250ml of water into a small pot and add the sachet of 120 g granulated sugar.
  3. Boil the mixture for 10 minutes and cover with a lid or foil (You can put the lid/foil on the pot the last minute of your boil to sanitise it).
  4. Cool the sugar solution down by putting the pot in a water bath with some ice.
  5. Once the solution is room temperature carefully pour it into your fermenter.
  6. Stir the beer gently with a sanitsed spoon to incorporate the sugar solution. Wait 30 minutes before bottling.


  1. Rinse the bottles well with water until there is no bleach residue/smell left.
  2. Fill the bottles 95 % with beer and put a sanitised cap on.
  3. Seal the cap with a capper.
  4. Leave the bottles in a dark area (20 C°) for two weeks to carbonate.
  5. After two weeks you can enjoy your beer!

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