We’ve had a can of Mountmellick Stout kicking around for a while. We also had small amounts of specialty malts in the grain cellar that needed using up, which are perfect for a mini-mash to go with the can.
Mountmellick is pre-hopped so we didn’t need additional bittering hops, but we had some left-over UK Fuggles to use for aroma. This should give the beer a bit more hop character above the malt extract’s bitterness.
Name: Mountmellick+ Batch size: 3 gallons Expected OG: 1.068 (75% efficiency) Expected FG: 1.017 Expected IBU: ? Partial Mash: 30m @ 153°F 4 lbs Mountmellick Stout pre-hopped extract 1.5 lbs Pale 2-row 7.0 oz UK Brown 4.0 oz UK Pale Chocolate (200L) 4.0 oz Belgian Special B 4.0 oz Briess C80L 3.0 oz UK Chocolate (425L) 2.0 oz Briess C120L 2.0 oz Briess C150L 0.5 oz UK Fuggle 5.3% AA @ 20m 0.5 oz UK Fuggle 5.3% AA @ 5m 1 pack Mountmellick yeast 1/2 pack Safale S05 dry yeast
We crushed the partial mash grains and heated our strike water to 160°F. Mash-in dropped the temperature to 152°F and we turned the stove on to raise temperature slightly. Once we got there, we turned off the burner and left the mash alone. Unfortunately the temperature at the top of the kettle wasn’t the temperature at the bottom,and when everything finally stabilized the entire mash was sitting at 163°F for about an hour. While unexpected, it won’t ruin the beer, since most of the sugar in the wort came from the Mountmellick can instead of our partial mash.
We removed our grain bag, sparged with more filtered water, and added that back to the main kettle. When the wort began to boil we moved part of it to a smaller pot and added the can of Mountmellick extract to that, mixing well to ensure nothing would scorch on the bottom. We added the small pot back to the kettle and proceeded with a 30 minute boil, starting at 17.5° Plato (1.072).
The astute among you will notice we’re already over our target gravity of 1.068, and after boiling the gravity would only be higher. It appears we completely mis-judged our efficiency and got closer to 90% of the potential extract from our the partial mash.
Since we weren’t trying to make an Imperial Stout we topped up with 1 gallon of cold filtered water to result in about 4 gallons of 15° Plato wort (1.061) before adding the yeast and fermenting at 68°F for about 10 days. When racking to the keg after fermentation was complete, the final gravity was 1.024 for about 4.9% ABV.
The result was a thick, black, roasty stout with significant bitterness and a dense rocky head that stuck around. Pretty good for an extract beer and a screwed-up partial mash. The bitterness was higher than we expected, but that’s probably because the pre-hopped malt extract can is meant for a 5 gallon batch and we were using it for 3.
What would we do differently next time, if another can of Mountmellick happened to drop from the sky? First, we’d move all our hop additions to 5 minutes or less, and use a hopstand to achieve more flavor and aroma. We’d also more tightly control the partial mash temperature to keep the beer lighter in body. But we’d also not bother doing a partial mash, since the gravity contribution of the pale malt is likely too high and would have significantly increased the alchohol had it been successful.