Question about full boil vs. partial boil

[sdufford]

Hi guys, I've been doing some reading on partial boil vs. full boil, and it's my understanding that you place some rather severe limits on your hop utilization with a partial boil.

My question is this- if doing say, 2.5 gal instead of 5 gal, with the full extract amount added at beginning, are you essentially placing a "ceiling" on your hop utilization to the point where no matter how many hops you add you will still max out at the same utilization? In other words, if brewing an extremely hoppy beer (like a double IPA), would doubling the amount of hops at each addition fully compensate for the PB or would you be essentially wasting hops at a certain point?

Hope that question makes sense. Thanks for the help!

 

[Delorean1981]

Bump. Would like to know this myself

 

[mixedbrewer]

You will get better hop utilization if you add the extract at the end of the boil. The more dense your wort is during the boil, the less room you have for the hops to make their way in. So maybe try adding a little bit of the malt extract at the beginning, and the rest of of it at the end of the boil. Just make sure it hits at the very least 160 degrees for 10 minutes.

 

[Grinder12000]

Question makes sense and BASICALLY I would tend to agree. I ran one of my IPA's through Brew Smith.

Full Boil I had 57 IBUs but when I went down to a 2 gallon boil it was only like 17 IBUs so then I doubled all of the hops and got it back to 47 IBU with doubling.

 

[SquirrelMaster]

and is it correct to say that once you dillute it to reach 5 gal your IBUs will be going down as well? say you did a 2.5 gal partial at 100 IBUs and then once topped up to 5gal it would be cut in half to 50?

 

[Hang Glider]

I don't know the maximum IBUs that 5 gallons of water can "hold" but full boils are better because if you reach the "hop-max" power of water in a partial boil (likely in an IIPA), you are then diluting it with the top-off water - unless, of course, you do two batches and combine them.

 

[mixedbrewer]

...or dry hop it

 

[Hang Glider]

...or dry hop it

yes, absolutely dry-hop!!!

the OP's question seems to center around the achievement of the bitterness level - the flavor and aroma certainly would be addressed with some (aggressive ! ) dry hopping - and might make up for a slight lack of bitterness, perceptually.

 

[sdufford]

Question makes sense and BASICALLY I would tend to agree. I ran one of my IPA's through Brew Smith.

Full Boil I had 57 IBUs but when I went down to a 2 gallon boil it was only like 17 IBUs so then I doubled all of the hops and got it back to 47 IBU with doubling.

Does Brew Smith account for the fact you're topping off after the boil? As in, is there a spot were you input boil volume and then a spot for "final batch volume"? It seems like if it doesn't then your final value of 47 IBU would then be cut way down again after you dilute, as SquirrelMaster said.

 

[Grinder12000]

Excellent question! I was assuming it was just utilization but perhaps they factor in the dilution due to adding water. hmmmm

 

[SquirrelMaster]

guess i need to plan on doubling the amounts of hops in the recipe i just put together for my first partial mash. Was most likely going to end up with around 2-2.5 gal of water post boil

 

[joetothemo]

Add another confused by brewsmith partial boil calculation. Promash does not have this issue of diminishing IBUs, nor does Tastybrew.com

 

[Boleslaus]

I use tastybrew and you can put in your boil volume and your batch size, so I assume that it knows you will top off your fermenter to reach the final batch size and calculate the IBU's accordingly.

 

[terrapinj]

Does Brew Smith account for the fact you're topping off after the boil? As in, is there a spot were you input boil volume and then a spot for "final batch volume"? It seems like if it doesn't then your final value of 47 IBU would then be cut way down again after you dilute, as SquirrelMaster said.

yup

it has a field for both batch size and boil size

 

[sdufford]

I guess we also all need to be aware that IBUs and hop utilization are two different things- IBUs are a measure of bitterness in a volume of beer, whereas hop utilization is just a percentage measurement of the amount of alpha acids fully isomerized from the hops...

...so...hop utilization would not drop by adding water, but IBUs would. But as stated before, hop utilization is inherently less from the beginning if boiling a higher density wort.

Please chime in if any of this is wrong!

 

[SumnerH]

Question makes sense and BASICALLY I would tend to agree. I ran one of my IPA's through Brew Smith.

Full Boil I had 57 IBUs but when I went down to a 2 gallon boil it was only like 17 IBUs so then I doubled all of the hops and got it back to 47 IBU with doubling.

Brew Smith (and other brewing software) use totally outdated algorithms that make erroneous assumptions (e.g. incorrectly assuming that hop utilization is affected by wort gravity). If you use their hop corrections, your partial boils will wind up much hoppier than they're intended to be. Unfortunately, there's no great solution out there that'll give you adequate adjustments, but in general (especially with extract brewing) you want to be a lot closer to the hopping schedule that software suggests for a full boil than the overly-aggressive partial boil adjustments they make.

Hop utilization is independent of wort gravity, and the impact (if any) of partial boils and late extract addition on IBUs is much, much smaller than what software will calculate.

The most recent test on this was Basic Brewing Radio's experiment where they brewed the same recipe (same hop schedule) as a full boil, partial boil, and partial boil with late extract additions, then measured the IBUs of the 3 beers in the lab. Hop utilization was essentially identical (the three came out with nearly the same IBUs).
March 4, 2010 - BYO-BBR Experiment III:
http://www.basicbrewing.com/index.php?page=radio

You can listen to John Palmer's "What is an IBU, Really?" from 20 March 2008 where he discusses the issue in some depth (including apologizing for getting this wrong in the most recent edition of How to Brew):
http://www.basicbrewing.com/index.php?page=basic-brewing-radio-2008

Now, there are some effects that often correlate with wort gravity that can impact final utilization--e.g. isomerized alpha acids can adsorb to break material. Those are much smaller effects than what brewing software calculates, though, and are pretty minimal in extract brewing (see the test above).

More discussion here:
https://www.homebrewtalk.com/f128/estimating-bitterness-algorithms-state-art-109681/
https://www.homebrewtalk.com/f14/hop-utilization-178668/

 

[SumnerH]

Hi guys, I've been doing some reading on partial boil vs. full boil, and it's my understanding that you place some rather severe limits on your hop utilization with a partial boil.

My question is this- if doing say, 2.5 gal instead of 5 gal, with the full extract amount added at beginning, are you essentially placing a "ceiling" on your hop utilization to the point where no matter how many hops you add you will still max out at the same utilization? In other words, if brewing an extremely hoppy beer (like a double IPA), would doubling the amount of hops at each addition fully compensate for the PB or would you be essentially wasting hops at a certain point?

Hope that question makes sense. Thanks for the help!

This is something that most brewing books and software get wrong--it's only recently that people (like John Palmer) have figured out more of what's going on and that other people (like BBR) have done experiments to test it out.

There is probably a theoretical saturation limit, but nobody knows what it is (you hear 100 IBUs get thrown around a lot, but that's pure speculation).

If you're below that limit, utilization seems unaffected by the size of the boil (though obviously a very small boil would reach whatever the saturation point is pretty easily).

As noted above, BBR actually ran the test last year--they brewed the same recipe (same hop schedule) as a full boil, partial boil, and partial boil with late extract additions, then measured the IBUs of the 3 beers in the lab. Hop utilization was essentially identical (the three came out with nearly the same IBUs).

March 4, 2010 - BYO-BBR Experiment III:
http://www.basicbrewing.com/index.php?page=radio

 

[mixedbrewer]

Why would anyone ever do a full boil extract again?

 

[SquirrelMaster]

glad to hear beersmith is wrong. so i shouldn't be worried that when i change the boil volume in beer smith from 5 gal to 3 that the IBUs go down in half? so if it says 110 at 5 gal it may be less at 3 gal but not the 65 ibus its telling me?

 

[SquirrelMaster]

so if this is my recipe and i plan on only having around 2.5-3gal of water after combining the strike and sparge water, i should be ok with having approximately the same amount of estimated IBUs after topping off to 5gal?

Type: Partial Mash
Date: 1/26/2011
Batch Size: 5.00 gal
Brewer: Scott
Boil Size: 4.89 gal Asst Brewer:
Boil Time: 90 min Equipment: Brew Pot (5 Gallon)
Taste Rating(out of 50): 35.0 Brewhouse Efficiency: 70.00
Taste Notes:

Ingredients

Amount Item Type % or IBU
8.34 lb Pale Liquid Extract (8.0 SRM) Extract 66.64 %
2.98 lb Pale Malt (2 Row) US (2.0 SRM) Grain 23.78 %
0.60 lb Carafa III (525.0 SRM) Grain 4.79 %
0.60 lb Caramel/Crystal Malt - 60L (60.0 SRM) Grain 4.79 %
2.00 oz Simcoe [13.00 %] (Dry Hop 7 days) Hops -
2.50 oz Chinook [13.00 %] (90 min) Hops 86.2 IBU
2.00 oz Amarillo Gold [10.00 %] (Dry Hop 7 days) Hops -
1.00 oz Simcoe [13.00 %] (10 min) Hops 11.7 IBU
1.00 oz Amarillo Gold [10.00 %] (10 min) Hops 9.0 IBU
1.00 oz Amarillo Gold [10.00 %] (1 min) Hops 1.1 IBU
1.00 oz Simcoe [13.00 %] (1 min) Hops 1.4 IBU
0.28 tsp Irish Moss (Boil 10.0 min) Misc
1 Pkgs American Ale (Wyeast Labs #1056) [Starter 125 ml] Yeast-Ale


Beer Profile

Est Original Gravity: 1.081 SG
Measured Original Gravity: 1.010 SG
Est Final Gravity: 1.019 SG Measured Final Gravity: 1.005 SG
Estimated Alcohol by Vol: 8.06 % Actual Alcohol by Vol: 0.65 %
Bitterness: 109.4 IBU Calories: 43 cal/pint
Est Color: 31.4 SRM Color: Color

 

[SumnerH]

Why would anyone ever do a full boil extract again?

Less caramelization of wort (better color and theoretically less extract twang), no worries about running up against a theoretical aa supersaturation point, maybe others. Usually by the time you're worried about that, partial mashing is on the table too.

 

[SumnerH]

glad to hear beersmith is wrong. so i shouldn't be worried that when i change the boil volume in beer smith from 5 gal to 3 that the IBUs go down in half? so if it says 110 at 5 gal it may be less at 3 gal but not the 65 ibus its telling me?

Well, there's where you get into a tricky area. I got interested in the subject because the hops corrections software was giving made everything too hoppy for my extract brews; personally I'd adjust a little bit (to account for the precipitation factor Palmer discusses in that podcast), but only maybe 10% more bittering hops and no adjustment on the 15 minute or less additions.

Unfortunately while the newer research shows that the old formulas are wrong, there isn't a well-accepted replacement yet; some people (including some really experienced brewers who know their stuff--e.g. YooperBrew) still think the old adjustments are fairly close, while others (including other experienced brewers who know their stuff, e.g. the measurements at BBR) would have you adjust very little or not at all.

 

[mixedbrewer]

This is great information. I will experiment more on my stove top for sure.

 

[molson]

Brew Smith (and other brewing software) use totally outdated algorithms that make erroneous assumptions (e.g. incorrectly assuming that hop utilization is affected by wort gravity). If you use their hop corrections, your partial boils will wind up much hoppier than they're intended to be. Unfortunately, there's no great solution out there that'll give you adequate adjustments, but in general (especially with extract brewing) you want to be a lot closer to the hopping schedule that software suggests for a full boil than the overly-aggressive partial boil adjustments they make.

Hop utilization is independent of wort gravity, and the impact (if any) of partial boils and late extract addition on IBUs is much, much smaller than what software will calculate.

The most recent test on this was Basic Brewing Radio's experiment where they brewed the same recipe (same hop schedule) as a full boil, partial boil, and partial boil with late extract additions, then measured the IBUs of the 3 beers in the lab. Hop utilization was essentially identical (the three came out with nearly the same IBUs).
March 4, 2010 - BYO-BBR Experiment III:
http://www.basicbrewing.com/index.php?page=radio

You can listen to John Palmer's "What is an IBU, Really?" from 20 March 2008 where he discusses the issue in some depth (including apologizing for getting this wrong in the most recent edition of How to Brew):
http://www.basicbrewing.com/index.php?page=basic-brewing-radio-2008

Now, there are some effects that often correlate with wort gravity that can impact final utilization--e.g. isomerized alpha acids can adsorb to break material. Those are much smaller effects than what brewing software calculates, though, and are pretty minimal in extract brewing (see the test above).

More discussion here:
https://www.homebrewtalk.com/f128/estimating-bitterness-algorithms-state-art-109681/
https://www.homebrewtalk.com/f14/hop-utilization-178668/

So I just want to make sure I understand. If I buy a recipie kit that is designed for a partial boil of 2.5 gallons, I can do a full boil without adjusting the amount of hops at all? I always thought I would have to make adjustments for the beer to come out as expected.

 

[SumnerH]

So I just want to make sure I understand. If I buy a recipie kit that is designed for a partial boil of 2.5 gallons, I can do a full boil without adjusting the amount of hops at all? I always thought I would have to make adjustments for the beer to come out as expected.

See my last note. Unfortunately there's no easy answer to that.

 

[molson]

See my last note. Unfortunately there's no easy answer to that.

So would it be a safer bet to make adjustments, or just leave it as is.

 

[SumnerH]

So would it be a safer bet to make adjustments, or just leave it as is.

I would maybe cut the bittering hops by 10% and leave the later additions the same. As I said above, reasonable minds disagree.

 

[Nova5]

I asked Forrest of AHS this on the stuff I got recently, he recommend reducing bittering hops by 20%.

 

[Rev2010]

Wow, this is great info! When I put in my amber ale in Beersmith the IBU change for my smaller boil got me worried. Guess everything may be perfect after all.


Rev.

 

[K5MOW]

Some great info.

Roger