Partials - Reducing top off, or how I maintained hop utilization

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Grumpybumpy

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I'm working on a recipe for an IIPA (Yooper's Ruination Clone modification) and I'd like to keep the hop utilization to a maximum. My last IPA is lacking in the bitter department. Here is Yoopers recipe with my modification to make it a partial mash:

(originally started with 14# pale malt, Original Gravity: 1.077)

8 lbs Pale Malt (2 Row) US (2.0 SRM) Grain
4 lbs Light DME (late addition)
1 lbs Caramel/Crystal Malt - 20L (20.0 SRM) Grain 6.67 %

1.75 oz Magnum [14.00 %] (60 min) Hops 73.2 IBU
1.00 oz Centennial [9.60 %] (30 min) Hops 22.1 IBU
1.00 oz Centennial [9.60 %] (10 min) Hops 10.4 IBU
1.00 oz Centennial [9.60 %] (1 min) Hops 1.2 IBU
2.00 oz Centennial [9.60 %] (Dry Hop 7 days) Hops -

1 Pkgs Pacman Yeast (Wyeast) [Starter 50 ml] [Cultured] Yeast-Ale

My process for BIAB partials with two 5 gallon pots has been as follows:
Strike with 3 gallons
Sparge with 1.5
Boil as usual

Efficiency has been around 68%

My pre-boil volume usually comes to about 3.8 gallons, which is plenty high in my brew kettle. However, by then end of a 60 min boil, I'm down to 3 gallons, leaving myself 2-2.5g of diluting top off water. It is my understanding that hop utilization goes down as gravity increases, so hopping in the concentrated wort will not be as efficient. On top of that, it'll be diluted by plain water.

Beersmith tells me that this method will result in 71 IBU, where the recipe should end at 103+

Aside from the late DME addition or adding lots of extra hops, I was thinking of ways to keep the IBU's high.

1. Do a 2nd sparge with 2 gallons, boil that thin wort for 60 min with .5 oz of magnum. Add that to the end of the main boil when there's some room in the kettle.
2. Boil a 2 gallon "hop tea" for 60 min with a small amount of DME the night before, cool it and use it as top off water. (comes to around 40 IBU)
3. Split the pre-boiled wort into two 5 gallon kettles, sparge until both reach 3 or 3.5 gallons. Split the hop additions between the two. (might be difficult with only 2 kettles and a bottling bucket)
4. Increase the boil time to 90 min (which means more boil off :cross:)

Any thoughts as to what would work best?
 
Adding extra hops wont help you increase the IBUs as you are hitting the solubility limit of isomerized alpha acids in your 3.8 gallons and then adding additional water later, which will reduce the concentration in the final volume, lowering the calculated IBUs.

Honestly, I think the easiest thing to do would be reduce your recipe so you can do a full volume boil in your current pot or do a split boil.
 
Right, I forgot about the max solubility of aa's.

I'd rather keep this as a 5 gallon batch as I give a good amount of my beer away. I've done a 3.5 gallon batch before and it didn't last long.

Of those other options, would any of them work?
 
Number 3 is a split boil. That's going to get you the closest to intended beer outside of a full boil.
 
I'm beginning to like the idea. Would it matter if I used only sparge water for the second pot? It could save a lot of mess. The only problem I can foresee is that I won't be able to accurately measure my pre boil gravity. Or maybe I could with a little math given the gravity of both pots... Hmm

Hop utilization in the sparge pot will be higher too...
 
I'd drain about half of the 1st runnings into each pot and then drain half of the sparge into each pot. Shouldn't be too hard to calculate how much you need from your grain bill and strike water volume.
 
So here's the plan...

I'm shooting for 5.2 gallons in the fermenter

3.5 gallon mash w/9# grain (volume comes to around 4.2 gallons in kettle)
less 1g to grain absorption
2.5 gallon post-mash volume

2 five gallon pots need 2.6g in each post-boil
3.7g boil in each assuming ~1g boil off

3.7g * 2 = 7.4 gallons between both pots

7.4g - 2.5g (post mash) = ~5 gallons for sparge

Total water usage: 8.5 gallons

I'm probably going to toss some of the runnings and some of the sparge into a bottling bucket then redistribute to get equal volumes in each kettle. Boil each as usual, halving the hops between each.

Has anyone else tried doing this method? Forsee any problems? The 3.5# dry malt extract might up the volume a bit, but that's ok. I'm anticipating a little more than 1 gallon of boil off in each kettle.

I'm getting pretty excited to try this. Too bad I'm on call this weekend, so I can't get too deep into something.
 
So I'm reading through "designing great beers" by daniels and he has a table that says 9# of grain will absorb 2 gallons of water. Does that seem like a lot to anyone else? I'm a bag squeezer....a grain bag squeezer...
 

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