Author Topic: Boil off percentage  (Read 624 times)

Offline chezteth

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Boil off percentage
« on: June 26, 2018, 12:05:14 AM »
I know there has been some discussion of boil off percentage with regards to LODO brewing practices. I seem to recall around 5% boil off is the goal. Depending on the starting boil volume 5% can be a very different amount. I brew some 5gal batches and mostly 3gal batches. If I used the same kettle and boil vigor for each batch size I would expect the same amount of boil off. I typically get about 3 liters of boil off in my kettle. For a starting volume of 17 liters that would be 17% boil off. For a starting volume of 28 liters that would be 10.7% boil off.
 
Should this target be set no matter the beginning boil volume?

Am I thinking way too far into this?

What size batches do you brew and what amount of boil off do you get?

Cheers,
Brandon

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Offline mabrungard

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Re: Boil off percentage
« Reply #1 on: June 26, 2018, 12:19:28 AM »
Boil off percentage has little to do with LODO. However, it does have a strong relationship to wort damage and premature staling of the finished beer. While evaporation losses as small as 2% have been cited in technical literature as producing acceptable beer, I question the study and its results. It appears that 6% to 10% is a more practical and workable target for Pro's and Homebrewers. I regularly limit my evaporation to 8% in a 60 minute boil and don't have issues with DMS. I was at 17% previously...OK, I didn't have DMS problems then either...even when brewing 100% pils grists.

Covering your kettle during the initial boil period and reducing your heat input make it possible to reduce evaporation losses and heat stress on your wort. Uncovering your kettle and conducting a modest and open boil for the later stage of your boil is also important. Volcanic boils are not helpful or useful.

I'm giving a comprehensive presentation on exactly this subject this Friday at HomebrewCon in Portland. AHA members should be able to view the presentation in a few months. There is a lot more to this than I've mentioned above.
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Offline BrewBama

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Boil off percentage
« Reply #2 on: June 26, 2018, 12:45:28 AM »
I am interested in seeing/hearing the presentation. I was one who thought boil meant ‘volcano’ and I was around 15% boil off. I now shoot for 8% and have struggled a bit in my effort even at what I’d consider a ‘simmer’.  I’ve been hitting 10% but decided to reduce boil times to 45 min in an attempt to further reduce boil off. Plus, I get the added benefit of slightly more volume in the fermenter to ensure I get a full keg in the end.

I take a slight hit in efficiency doing these things but the last couple beers have been noticeable better with this and the additional changes in process (step mash, recirculating, etc), equipment (pump, RIMS, etc), and ingredients (Brewtan B). Maybe bias but I’m digging it so....


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« Last Edit: June 26, 2018, 12:59:05 AM by BrewBama »
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Offline Robert

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Re: Boil off percentage
« Reply #3 on: June 26, 2018, 01:03:21 AM »
My beer is astonishingly improved with gentler treatment these days.   I've mentioned elsewhere, if you can heat your kettle asymmetrically, you can get rolling circulation with less heat.  Efficiency?  Saving a buck's no good if the beer is worse for it.   I'm digging it too. Look forward to the eventual release of the presentation. 
Rob Stein
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Offline The Beerery

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Re: Boil off percentage
« Reply #4 on: June 26, 2018, 01:14:26 AM »
Well, it was the Low oxygen folks that brought this information forward, and took quite the lickin from folks about it...Glad to see people are slowly coming around. TBI is real (where have I heard that before :) ).

Offline Robert

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Re: Boil off percentage
« Reply #5 on: June 26, 2018, 01:27:57 AM »
Well, it was the Low oxygen folks that brought this information forward, and took quite the lickin from folks about it...Glad to see people are slowly coming around. TBI is real (where have I heard that before :) ).
Nice to see you again, Beerery.  What I've realized is that even though I didn't ever self-identify as a LODO partisan, there's not much daylight between us (especially since I've taken to bisulfites in the mash and sparge to complement my very tight cold side practices,) because, apart from a few special procedures, most of what you guys advocate is simply sound, attentive brewing practice.  I think the subject of thermal stress is well within that category. Not everyone can pre-boil or spund, but turning the burner down, well ... turn it down!  :)
Rob Stein
Akron, Ohio

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Offline The Beerery

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Re: Boil off percentage
« Reply #6 on: June 26, 2018, 01:42:58 AM »
Well, it was the Low oxygen folks that brought this information forward, and took quite the lickin from folks about it...Glad to see people are slowly coming around. TBI is real (where have I heard that before :) ).
Nice to see you again, Beerery.  What I've realized is that even though I didn't ever self-identify as a LODO partisan, there's not much daylight between us (especially since I've taken to bisulfites in the mash and sparge to complement my very tight cold side practices,) because, apart from a few special procedures, most of what you guys advocate is simply sound, attentive brewing practice.  I think the subject of thermal stress is well within that category. Not everyone can pre-boil or spund, but turning the burner down, well ... turn it down!  :)


I have always said.  Low oxygen brewing is 99% sound brewing process and 1% wizardry. 


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Offline chezteth

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Re: Boil off percentage
« Reply #7 on: June 26, 2018, 01:45:08 AM »
So, what I understand so far is I should aim for <10% boil off no matter what volume I start with, correct?

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Offline Robert

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Re: Boil off percentage
« Reply #8 on: June 26, 2018, 01:53:35 AM »
So, what I understand so far is I should aim for <10% boil off no matter what volume I start with, correct?

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Aim for, sure, but with smaller batches, kettle geometry is going to make this difficult of course.  But I've come to see evaporation rate as an index of thermal loading, not an end in itself.  So reducing the length and intensity of the boil is your goal.  It's just easier to manage not overstressing the wort the bigger the batch, up to commercial scale.   Imagine you had only an ounce of wort.  Apply any heat at all, and boom, it's burnt sugar on the kettle surface.
Rob Stein
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Offline chezteth

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Re: Boil off percentage
« Reply #9 on: June 26, 2018, 02:05:24 AM »
Thanks for the replies. I've been stuck on the whole idea of boil off percent. Reducing the boil off by reducing the vigor and keeping the lid on for part of the boil is definitely in my future. I will strive to reduce the boil off as much as possible. I am also changing other parts of my process to reduce oxidation.
I'm also looking forward to Martin's presentation once it is released.

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Offline BrewBama

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Re: Boil off percentage
« Reply #10 on: June 26, 2018, 12:47:52 PM »
Well, it was the Low oxygen folks that brought this information forward, and took quite the lickin from folks about it...Glad to see people are slowly coming around. TBI is real (where have I heard that before :) ).

Yes, the authors Ancient Abbey, Brandon, Techbrau, and Weizenberg (aka - 'The Team at German Brewing Forum') and the primary sources they cite, have brought about significant change in the homebrewing community over the last couple years to be sure.  It's a shame they didn't have a PR guy to soften the blow.

Brains from Heaven indeed (or Stones...).
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Offline The Beerery

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Re: Boil off percentage
« Reply #11 on: June 26, 2018, 01:10:39 PM »
Well, it was the Low oxygen folks that brought this information forward, and took quite the lickin from folks about it...Glad to see people are slowly coming around. TBI is real (where have I heard that before :) ).

Yes, the authors Ancient Abbey, Brandon, Techbrau, and Weizenberg (aka - 'The Team at German Brewing Forum') and the primary sources they cite, have brought about significant change in the homebrewing community over the last couple years to be sure.  It's a shame they didn't have a PR guy to soften the blow.

Brains from Heaven indeed (or Stones...).
ACTUALLY, the Team at German brewing was those folks AND Steve and Myself, with Brandon and myself assembling said "team"... So cite your sources correct ;)

Offline BrewBama

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Re: Boil off percentage
« Reply #12 on: June 26, 2018, 01:12:03 PM »
Well, it was the Low oxygen folks that brought this information forward, and took quite the lickin from folks about it...Glad to see people are slowly coming around. TBI is real (where have I heard that before :) ).

Yes, the authors Ancient Abbey, Brandon, Techbrau, and Weizenberg (aka - 'The Team at German Brewing Forum') and the primary sources they cite, have brought about significant change in the homebrewing community over the last couple years to be sure.  It's a shame they didn't have a PR guy to soften the blow.

Brains from Heaven indeed (or Stones...).
ACTUALLY, the Team at German brewing was those AND Steve and Myself.. So cite your sources correct ;)

Sorry, I was simply going off the paper.  Didn't mean to exclude.  (You should have your names added.)
« Last Edit: June 26, 2018, 01:13:48 PM by BrewBama »
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Offline brewinhard

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Re: Boil off percentage
« Reply #13 on: June 26, 2018, 02:32:15 PM »
Thanks for the replies. I've been stuck on the whole idea of boil off percent. Reducing the boil off by reducing the vigor and keeping the lid on for part of the boil is definitely in my future. I will strive to reduce the boil off as much as possible. I am also changing other parts of my process to reduce oxidation.
I'm also looking forward to Martin's presentation once it is released.

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FWIW, I start with a 7 gallon pre-boil, 60 min low vigor boil (boil off around 8%) and finish with a 6.5 gallon post boil. I transfer 5.5 gallons crystal clear wort into the fermenter leaving behind trub/hops and get 5 gallons into my kegs.

Offline denny

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Re: Boil off percentage
« Reply #14 on: June 26, 2018, 02:35:27 PM »
Martin, will you have beers to taste?  I'd love to see the difference.
Life begins at 60.....1.060, that is!

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