St. Bernardus Abt 12 Partial Mash (2021-05-15)
- Brewed: May 15, 2021
- Packaged: May 28, 2021
- On Tap: July 9, 2021
- Recipe: St Bernardus Abt 12 Clone Partial Mash
Looking to use my packets of T-58 I have around and branch out more with my brewing, I went with a Belgian Dark Strong Ale this time. After some research, I picked a St. Bernardus Abt 12 clone recipe published by Candi Sugar Inc because I really like the original beer and it is a very simple base recipe which will give me room to experiment and make it my own. As noted on my recipe, I converted their recipe to partial mash and changed up the yeast along with a wild guess as to what I should use for "Caramelized Beet Sugar (Dark)"
Preboil SG: N/A
Original gravity: 1.078
Final gravity: 1.017
Volume in Fermenter: 2.9 Gallons
Mash and Boil Process
Once again, things were changed up from my usual process by going partial mash to reduce weigh on the stove. The original recipe's need for around 7lbs of grain and enough water for a 90 minute boil was pushing the limits a bit too much. I got by with it a few weeks ago for my Weizenbock but I just didn't feel like pushing my luck again.
I started with a full volume mash of about 4 gallons of water. Really, the calculators called for about 3.96, so I figured 4 is close enough. I mashed the 3 lbs of pilsner malt and the Carafa III Special for 75-80 minutes. My target temperature was about 148F. I got considerably lower than that and so extended the time, but I figure this may help with more fermentable sugars from the pilsner malt to help make up for the LME which was probably mashed closer to 152F.
After that I boiled for 60 minutes, figuring the original recipe's 90 minute boil was likely primarily to evaporate more DMS with the large amount of pilsner malt rather than for maillard reaction. I added the 3.3 Lbs of malt extract with about 15 minutes left in the boil and 0.75 Lbs of D-180 and 0.75 Lbs of D-90 with about 5 minutes left.
When everything was complete I had a lot more wort than expected at closer to 3.25 gallons. I verified all of my numbers and everything looked good. My best guess is that with so little grain the water absorption was lower than expected, but I use a pretty low estimate of that at 0.045 gallons/lb of grain based on biabcalculator.com usually coming out about right for me. With so little grain and such low absorption, even if I was a bit low, there's just not much room to have been off much. The other big factor would be boil off rate. My boil off rate is generally around 1.05 gallons/hr which is also pretty low. Really the only option is that I was much lower than that somehow. I have been fiddling with the lid on my boil kettle, but honestly don't remember ever being consistent about it, so I am left wondering if I need to leave it off to allow more steam to easily escape or leave it covering a bit to get a more vigorous boil. 1.05 gallons/hr out of a usual 3.5-4.5 gallon boil is also a very high percentage which leaves me wondering if I actually have a much lower boil off rate and should be calculating by percentage although all of the tools use a flat gallons/hour. A 10%/hour boil off rate puts me much closer to where I landed.
In the end I dumped some of the wort because I have a 3 gallon fermenter plus head space, so I wasn't leaving any room for the large amount of krausen T-58 produces.
I pitched a full packet of T-58 at 63F and set my temperature controls to maintain 64F for the first day. On day two I bumped to 65F and fermentation was already well on its way. On day 3, the 17th I increased the temperature to 66F. On the 18th the temperature increased to over 68F on its own. I held at 69F-70F until the 22nd and then increase to 72F. After that I let nature take its course, keeping the beer in an insulated but no longer chilled fermentation chamber in the garage where it hit temperatures as high as 77F.
Post Fermentation - 2021-05-28
I can't complain. My final gravity ended up about 1.017, which is closer to the original recipe's 1.012 than any calculators said I would get with T-58 even with having a good bit of the fermentables being malt extract and so unaffected by my mash temperature choices. That comes out to about 78% apparent attenuation which is definitely at the high end for T-58, which has somewhat confusing information from Fermentis on their site claiming 72%-78% attenuation but a graph showing it topping out at 70%. I kegged today with 110 grams of corn sugar and will now let the beer sit at 70-75F until July. Even my unaged, 75F, flat sample I drank today was delicious so I have high expectations for this.
I hooked the already chilled and carbonated keg up and had a good pour of the beer. It may have fermented a bit warm for the T-68 yeast, the fruitiness is a bit much and there's a sourness to it which was also in my Weizenbock which used T-68. There is also a noticeable alcoholic taste in the finish. I'm going to drink this slowly and see how it ages. I expect the alcohol to fade and the beer to improve. I will try it again as an all grain recipe and may keep the fermentation temperatures a bit lower and will also experiment with other yeasts, particularly Danstar Abbaye and Fermentis Abbaye.
|1.075 - 1.110||1.010 - 1.024||20 - 35||
12 - 22 srm
|Brewed On||Packaged On||On Tap Date||Original Gravity||Final Gravity||Color|
|May 15, 2021||May 28, 2021||July 9, 2021||1.078||1.017||