BIAB Parti-gyle (1 gallon batches)

Waiting for my mash to finish so thought I might as well post this.

The plan today is to brew two 1-gallon batches using the same grain bill; an imperial stout and a dry stout. The idea and recipes are from Mike Karnowski's book 'Homebrew beyond the basics'.

I will brew the imperial stout as I normally do (full volume mash). As I understand it I probably won't get my usual efficiency (75%) so after the mash I will see what the OG is and then decide whether to squeeze the bag to get closer to the planned OG of 1.100 or whether to leave the bag drain a bit and leave the sugars still in the bag for the second beer. In that case I will then bump up the imperial stout with some DME.

The grain bag will be placed in a cooler and I'll add 5,5L of water, stir and leave it for 15 minutes. I will then check the gravity and see where to go from there. If it looks like the gravity is good enough to get a 1.040 dry stout then I will proceed but if the second wort is looking and tasting thin I'll add some crystal malts to steep and try and get a nice mild out of it by adding some DME to the boil.

Mash time is up. I'll update this later in case anyone's interested.

After a 60 minute mash I checked the gravity with a refractometer. It was at 1.064 as opposed to a planned pre-boil of 1.068 so that is good enough for me. I pulled the grains and gave a moderate squeeze and started the boil for the imperial stout.

I placed the grain bag in a small cooler and poured in 5,5L of 74C water. I'm not counting on losing any water to the grains now as they should be saturated so that will be my pre-boil volume. Stirred for a few minutes and then left for 10 minutes. Another good stir and then checked the gravity. It was roughly 1.025 and doesn't look nearly dark enough for a dry stout so decided this is going to be a mild. Added some crystal 60 and 120 to the grains and will leave them for 30 minutes to steep. Hopefully the original grain bill of pale, brown malt and black patent will add enough malty character to the final product.

Update:

The imperial stout is now in the fermenter and yeast is pitched. OG of 1.094.

I also pulled the grains out of the cooler and the second/small beer is at 1.026 which would boil down to 1.039 according to Beersmith, which would be spot on for a mild.

The brewing gods have called me on my hubris. I've just realised I don't have a clean fermenter for the second beer. I have a batch I can bottle so no biggie.
But I also have 1 litre over of the imperial stout as I like to leave that in the kettle with the hop junk. If I strain the remaining wort and add that to my second wort that would bump my starting gravity by quite a bit and add significant flavour (I think). On the other hand the remaining wort from the imperial is hopped to 125 IBUs so I imagine a fair bit of bitterness will end up in the second wort. If I do that I will have no idea how to hop my second wort and would have to go by taste.

I won't be able to start boiling the second wort for a few hours now so would appreciate any ideas on how to proceed.

Edit: I decided to combine. This should leave me with a starting gravity in the 1.047 range and even though the new combined wort has a bit of bitterness I will add another 35 IBUs. Better bitter than sorry.

All in all, it's been a fun brew day, although I still have to do the second boil. Parti-gyle works but it's certainly less predictable using full volume BIAB.

Interesting report. I'll be curious to hear how they turn out!

Nice adjustments. I would've lowered the ibu of the planned mild to account for 25 ibu diluted to whatever the final volume was.

If you really want to partigyle I'd suggest doing a normal mash by grain/water thickness ratio rather than full volume.

pricelessbrewing said:

Nice adjustments. I would've lowered the ibu of the planned mild to account for 25 ibu diluted to whatever the final volume was.

If you really want to partigyle I'd suggest doing a normal mash by grain/water thickness ratio rather than full volume.

Click to expand...

Yeah, I was just curious if it was even possible doing full volume BIAB.

For anyone interested, I just bottled the small beer. Despite all the hassles I had with getting the brew into the fermenter (original mash on Friday, didn't pitch yeast until Sunday lunchtime) it turned out very nice. I pitched Safale T58 as I realised I did not have any other yeast at home. The OG was 1.041 and FG 1.011. It is not quite a dry stout as I capped the second mash with crystal malts and it's a bit roasty for a mild but as a session beer I think it is going to be pretty drinkable. Adding the leftover wort from the RIS boil definitely saved this from being an overly watery mild. Will definitely do this again if I ever brew another RIS. Jury is still out on that as the RIS is still in primary and won't be bottled fr another few weeks.