Well now. Fumble is a strong word. But by the numbers, yeah, missed it by that much! But recovered, rather than dumping the beer.
Recently I re-brewed an old Robust Porter recipe, confident that with the experience I have gained over the last few years it would turn out better than the previous brew. I am not going to list the recipe here… you can review my thread at the AHA forum if you would like here. And here is the crux of the discussion.
I achieved a much higher efficiency than expected while using the same recipe (something I should have expected!). I pitched Nottingham yeast, rehydrated and at the appropriate rates into the wort. However, after 7 days in primary, the fermentation stalled at 1.025 – far to sweet and high for a Robust Porter. I had high hopes for this.
I pitched 3 rehydrated packages (previously I sprinkled 2 dry packages) of Nottingham at 64F. Fermentation took off as expected and I let the fermentation naturally rise to 68F. After a week and a couple of days gravity stuck at 1.025, I pitched another rehydrated active slurry of S-04. Gravity remained the same. I posted on the AHA forum asking for advice, and got some good ideas. I recently brewed a hoppy American Brown ale, took some excess from the cooled and oxygenated wort, and pitched a fresh package of Notty into that – and at high krausen, tipped the lot into the porter.
Fermentation took off, although I wouldn’t call it vigorous. 3 days later, no drop in FG. We did manage to shave it down to 1.023, but that maybe to dilution from the starter. Remember my OG was 6 points high and I finished basically 6 points high.
There are two fundamental issues at play here:
First, I used a recipe from the past that was not re-tuned to my current setup, capability or more more educated taste. The OG was 6 points higher because my system efficiency has increased. I also did not have the temperature controls that I have today – so my notes indicate 68F at pitching the first time, and I now pitch several degrees lower than fermentation temps and let the wort free rise to fermentation target temperatures.
I would love to blame a bad batch of Nottingham yeast, but cannot. S-04 and a later pitch of active and new Nottingham failed to bring the gravity any lower. I should note that S-04 was not the best choice as its minimum attenuation is lower than Nottingham. My bad.
Secondly, a review of the recipe reveals an overly large portion of specialty malts. Namely a portion of British Brown Malt and Carared… adding, along with some of the roasts, unfermentables. It is possible that I mis-measured my grist and/or I didn’t write down an accurate FG.
The second issue is the real eye opener. I am a far more detailed brewer that I was just a few years ago. So, note to myself, revisit recipes each time to make sure they are tuned to my system, my palette and meet my more educated expectations!
As suggested by Jon in the AHA thread, I cold steeped some locally sourced roasted coffee. I intentionally made it stronger than normal, and after 2 days it was ready. I took a sample of the porter and slowly added higher concentration of coffee. After some tasting, I chucked the lot into batch and started to cold crash. I expected to need to add more, but tasting before kegging – there was a very nice balance.
Now that the porter is kegged and carbing, this will be a really nice beer. Not something I would expect to do well in competition, perhaps, given the high final gravity, but a solid porter with subtle roasty notes, some coffee, nut and vanilla in the finish. Looking forward to this one! And making adjustments to the recipe to ensure proper attenuation, a slightly lighter color and a tweak to the roast character without adding coffee.