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Author Topic: The Kernel Imperial Brown Stout  (Read 4294 times)

Offline Philip McCaugherty

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The Kernel Imperial Brown Stout
« on: June 06, 2019, 06:43:29 am »
Hi

Can anyone explain the high IBU's that are calculated for this recipe? I have put the numbers into Brewer's Friend and am not getting anywhere close to the 120 IBU's that are stated for this recipe. And that's with Tinseth and Rager. Is there a 3rd IBU calculator that I am unaware of?

Thanks in advance
Phil
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Offline goose

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Re: The Kernel Imperial Brown Stout
« Reply #1 on: June 06, 2019, 07:15:02 am »
We need more information.  What is the recipe?
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Offline Robert

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Re: The Kernel Imperial Brown Stout
« Reply #2 on: June 06, 2019, 07:32:11 am »
120 IBU is physically impossible anyway.   Around 100 mg/L is the theoretical saturation limit for iso-alpha acids in a low gravity wort, and that is greatly reduced by both increasing gravity, and, counterintuitively, increasing hop rates.  The most that will probably ever occur in finished beer is still shy of 80 IBU.   High advertised IBUs are just machismo on the part of brewers.  Ignore the numbers, brew the recipe, and see how you like it.

(Also note that the Tinseth and Rager calculators are capable of generating such an impossible number.  But remember that these tables are really just their individual SWAGs at what they were getting on their own systems back in the day, extrapolated out to increasingly imaginary ranges.  The fact that these tables have been canonized and enshrined in every book and software program published for a couple of decades tells us a lot about homebrewers' obsession with numbers, but very little about what's in our beer.)
« Last Edit: June 06, 2019, 07:50:05 am by Robert »
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Offline Philip McCaugherty

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Someone once told me that making my own beer was a great way to save money. What a load of shyte that was!

Offline Philip McCaugherty

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Re: The Kernel Imperial Brown Stout
« Reply #4 on: June 06, 2019, 08:24:33 am »
120 IBU is physically impossible anyway.   Around 100 mg/L is the theoretical saturation limit for iso-alpha acids in a low gravity wort, and that is greatly reduced by both increasing gravity, and, counterintuitively, increasing hop rates.  The most that will probably ever occur in finished beer is still shy of 80 IBU.   High advertised IBUs are just machismo on the part of brewers.  Ignore the numbers, brew the recipe, and see how you like it.

Yeah mate, I know they're a minefield and that some breweries rip the arse out of their calculations. But these numbers seem way OTT. I really would like to make this brew as good as I possibly can because the original is an epic beer. And the thought of having a keg full of the stuff has me salivating.
Someone once told me that making my own beer was a great way to save money. What a load of shyte that was!

Offline denny

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Re: The Kernel Imperial Brown Stout
« Reply #5 on: June 06, 2019, 08:25:45 am »
We need more information.  What is the recipe?

https://www.homebrewersassociation.org/homebrew-recipe/the-kernel-imperial-brown-stout-london-1856/

Ah, that explains it.  Historical British beers are very often hopped at an extremely high rate.   That's just the way it was back then.  If you look at the Durden Park Circle recipes, some of them have unbelievable IBU levels....but that's what they did.

ETA:   I took the 1856 to be the year it's from.  Probably totally off the mark on that.
« Last Edit: June 06, 2019, 08:27:20 am by denny »
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Offline Robert

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Re: The Kernel Imperial Brown Stout
« Reply #6 on: June 06, 2019, 08:34:52 am »
Remember that these historical beers had enormous hop charges, but we don't really know the IBUs.  Nor did they.  They were brewed according to custom, and empirically developed recipes, but the science was still nascent.   Moreover,  looking at old recipes in, e.g. Ron Pattinson's work, you'll see that the hops were regularly several years old and were not stored in what we would regard as the proper manner.  Reproduction of historical beers really is more of an interpretive art than anything else.   But great fun.
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Offline Philip McCaugherty

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Re: The Kernel Imperial Brown Stout
« Reply #7 on: June 06, 2019, 08:35:52 am »
We need more information.  What is the recipe?

https://www.homebrewersassociation.org/homebrew-recipe/the-kernel-imperial-brown-stout-london-1856/

Ah, that explains it.  Historical British beers are very often hopped at an extremely high rate.   That's just the way it was back then.  If you look at the Durden Park Circle recipes, some of them have unbelievable IBU levels....but that's what they did.

ETA:   I took the 1856 to be the year it's from.  Probably totally off the mark on that.

Den

I think you are correct in that the original year of the recipe is 1856. That is pretty much what The Kernel do. They have loads of historical recipe beers. My query is how, with that amount of hops in the recipe, did the calculator churn out a number of 120.1 IBU's? It doesn't seem possible. I have reached that number using Brewer's Friend but I had to use a lot more hops and use Rager as the calculating tool.
Someone once told me that making my own beer was a great way to save money. What a load of shyte that was!

Offline denny

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Re: The Kernel Imperial Brown Stout
« Reply #8 on: June 06, 2019, 08:50:11 am »
We need more information.  What is the recipe?

https://www.homebrewersassociation.org/homebrew-recipe/the-kernel-imperial-brown-stout-london-1856/

Ah, that explains it.  Historical British beers are very often hopped at an extremely high rate.   That's just the way it was back then.  If you look at the Durden Park Circle recipes, some of them have unbelievable IBU levels....but that's what they did.

ETA:   I took the 1856 to be the year it's from.  Probably totally off the mark on that.

Den

I think you are correct in that the original year of the recipe is 1856. That is pretty much what The Kernel do. They have loads of historical recipe beers. My query is how, with that amount of hops in the recipe, did the calculator churn out a number of 120.1 IBU's? It doesn't seem possible. I have reached that number using Brewer's Friend but I had to use a lot more hops and use Rager as the calculating tool.

Sure, it's entirely possible to ha e numbers calculate that high.  I once made an American variations that called to 135 IBU.  Obviously, as pointed put in the Durden Park book, it's impossible to know what the AA of the hops in the original recopes is, and they certainly didn't know either.  Just the amount.

And a side note on calculations...when we interviews Glenn Tinseth for Experimental Brewing, he made it clear that unless you used whole hops, had a brewing setup exactly like his and chilled for the same length of time he did,  there was no reason to expect you'd get the same results he did.  The takeaway is that IBU calcs are highly variable and not necessarily reliable.  When we did an experiment to test that, we found results as much as +/- 50% from the calculated value.
Life begins at 60.....1.060, that is!

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Offline Kevin

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Re: The Kernel Imperial Brown Stout
« Reply #9 on: June 06, 2019, 09:13:46 am »
Kernel Brewing in London re-created this beer from an 1856 Barclay Perkins recipe. Everything in the recipe submitted to Zymurgy matches up with Barclay Perkins IBS ex recipes from the mid 1850's all the way to the 1950's except these IBU numbers. The OG, the ABV and SRM all line up with the original but the IBU's of Barclay Perkins Stouts are generally in the low to upper 50's. The sites that rate commercial beers do not give an IBU for the Kernel commercial beer so it would seem the contributor of that recipe took a WAG.
« Last Edit: June 06, 2019, 09:16:00 am by Kevin »
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Offline Robert

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Re: The Kernel Imperial Brown Stout
« Reply #10 on: June 06, 2019, 09:24:34 am »
Kernel Brewing in London re-created this beer from an 1856 Barclay Perkins recipe. Everything in the recipe submitted to Zymurgy matches up with Barclay Perkins IBS ex recipes from the mid 1850's all the way to the 1950's except these IBU numbers. The OG, the ABV and SRM all line up with the original but the IBU's of Barclay Perkins Stouts are generally in the low to upper 50's. The sites that rate commercial beers do not give an IBU for the Kernel commercial beer so it would seem the contributor of that recipe took a WAG.
I'm curious.  If I get the time I'm going to see if I can find anything in Ron's work giving original hop rates for these IBS ex's of the period.  It would have been scheduled in pounds of hops per quarter of malt.  From this we might take our own WAG at the alpha content of the hops and guesstimate a bitterness number.  Then taking into account the fact that vatting would have further reduced bitterness, which a modern brewer will not match, we could come up with our own adjusted guideline for historical reproductions also based on quantity of hops rather than IBU calculations.   Going out on a limb, I'd bet we'd want to use no more than half the weight of hops, scaled down, that the original brewers used.
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Offline Philip McCaugherty

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Re: The Kernel Imperial Brown Stout
« Reply #11 on: June 06, 2019, 09:31:17 am »
I have emailed The Kernel, asking them for their estimated IBU's for this beer. They were very helpful when I asked them about the recipe on this website so I am hopeful they will come back to me with something.
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Offline kramerog

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Re: The Kernel Imperial Brown Stout
« Reply #12 on: June 06, 2019, 12:10:07 pm »
I think the IBUs in a professional system can be higher than in a homebrew setting because the boil temperature is higher in a tall tank due to water pressure.  Perhaps I'm imagining this. 

Anyway, the purpose of IBUs in a beer that should be aged is so that there is a reasonable amount of bitterness around when you want to consume it, maybe 6-18 months after brewing. For this purpose, a calculation of 70 IBUs or 110 IBUs is pretty much the same thing.

Offline denny

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Re: The Kernel Imperial Brown Stout
« Reply #13 on: June 06, 2019, 01:06:22 pm »
I think the IBUs in a professional system can be higher than in a homebrew setting because the boil temperature is higher in a tall tank due to water pressure.  Perhaps I'm imagining this. 

Anyway, the purpose of IBUs in a beer that should be aged is so that there is a reasonable amount of bitterness around when you want to consume it, maybe 6-18 months after brewing. For this purpose, a calculation of 70 IBUs or 110 IBUs is pretty much the same thing.

Yeah, temp has nothing to do with once you reach isomerization temp.
Life begins at 60.....1.060, that is!

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Offline Robert

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Re: The Kernel Imperial Brown Stout
« Reply #14 on: June 06, 2019, 02:22:45 pm »
I think the IBUs in a professional system can be higher than in a homebrew setting because the boil temperature is higher in a tall tank due to water pressure.  Perhaps I'm imagining this. 

Anyway, the purpose of IBUs in a beer that should be aged is so that there is a reasonable amount of bitterness around when you want to consume it, maybe 6-18 months after brewing. For this purpose, a calculation of 70 IBUs or 110 IBUs is pretty much the same thing.

Yeah, temp has nothing to do with once you reach isomerization temp.
Kettle geometry and circulation can affect utilization rates, as well as the amount of oils retained in wort.  The bigger the batch the more you get from the hops, it seems.  Some things just don't scale precisely from commercial to homebrew batch size.
Rob Stein
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