Brewfather IBU seems wrong for Sierra Nevada clone?

[deeve007]

Hey brewers!

I'm wanting to do a Sierra Nevada pale ale clone, directly from their published recipe: How To Make Pale Ale - Our Pale Ale Recipe - Sierra Nevada Brewing Co.

10L though rather than 20L/5 gallons, so have halved everything roughly: Brewfather

But the IBUs shown on Brewfather are almost double what they should be, both from the IBU of the beer itself, and other clones I've found online.
Is there an issue with how Brewfather calculates IBUs, or something wrong with my recipe I'm not seeing?

Cheers.

Edit: I'm adjusting hop amounts in Brewfather now, so will be lower IBUs now.

 

[VikeMan]

A picture might be worth a thousand words here.

 

[deeve007]

A picture might be worth a thousand words here.

Sorry I'm not sure what you mean?

 

[VikeMan]

Sorry I'm not sure what you mean?

I see you linked to your recipe in Brewfather. So that'll work.

The Brewfather IBUs look about right to me, given the inputs.

The first thing that jumps out is that for the 30 minute addition (and the Flameout addition), Sierra Nevada's recipe calls for 2 ounces. Half of that would be ~23 grams, not 28 grams.

Also, Brewfather is computing IBUs for the Flameout ("Hopstand") addition. Chances are Sierra Nevada didn't count any IBUs for that addition when they wrote the recipe, as the math for that only appeared relatively recently (compared to the history of SNPA).

Also, your recipe assumes 5.5% Alpha Acids for the hops. Sierra Nevada may be assuming something lower when specifying the qtys.

Also, SNPA uses whole cone hops, which don't produce quite the same level of IBUs (for a given AA%) as pellets (which I assume Brewfather may be assuming...I dunno, I don't use Brewfather).

ETA: One last also... Sierra Nevada may be using some Bitterness calculation other than Tinseth, which is what Brewfather appears to be using.

 

[deeve007]

So I found this IBU calculator: IBU Calculator Beer Bitterness - Brewer's Friend
...and entered in the hop schedule and amounts from the original Sierra Nevada recipe, and the IBU calculates as 52, and not 38 like the actual beer. And the calculator added no IBUs for hops added at 0 minutes in boil, which I know is not entirely accurate.

So now I'm not sure how to take - and use - their recipe with regards to the IBU, do I run with it, or do I adjust their earlier hop amounts to get the IBUs closer to their retail beer??

 

[mac_1103]

I have found that calculator to give higher than expected IBU pretty often when I just enter recipes that I've found online. Haven't really been able to figure out why. Does the original recipe specify the alpha acid content of each hop used? Are they the same as the ones you have? Did you use the values that the calculator has built into it for different hop varieties, or did you manually enter the values from the packages that you actually have on hand?

 

[deeve007]

I have found that calculator to give higher than expected IBU pretty often when I just enter recipes that I've found online. Haven't really been able to figure out why. Does the original recipe specify the alpha acid content of each hop used? Are they the same as the ones you have? Did you use the values that the calculator has built into it for different hop varieties, or did you manually enter the values from the packages that you actually have on hand?

I went by AA from hop pellets I have, but I guess I do need to try to work out what their whole hops AA is... damn why don't they write that, for anyone using their recipe??

 

[VikeMan]

I went by AA from hop pellets I have, but I guess I do need to try to work out what their whole hops AA is...

You're not going to have enough information to work out what their AA assumption was, given that you don't know what model they used, and don't know whether 38 IBUs is measured or theoretical. But it should be useful information knowing that they use whole hops. All else being equal, expect about 10% less utilization from whole hops as compared to pellet hops with the same AA content.

Why not start with an assumption that the AAs are about the same as what you have (5.5. is kind of middle of the road for Cascade), cut back the qtys by about 10% for your pellets, brew it, and see?

 

[deeve007]

Why not start with an assumption that the AAs are about the same as what you have (5.5. is kind of middle of the road for Cascade), cut back the qtys by about 10% for your pellets, brew it, and see?

Yeah without more info it may end up being a "brew it and see" time.

 

[dmtaylor]

If you are using pellets, my own formula says it will be about 46 IBU. Very consistent with Brewfather. If Sierra Nevada is using late hop / whirlpool additions but ignoring this in a calculated value for IBUs, then their IBU calculation is incorrect. But they might also be measuring the real IBU value in a lab. I haven't seen all the sources for whatever you were shooting for, but I would say that the consistency of several calcs anywhere in the mid 40s for IBUs isn't going to be far off from a clone of this beer; and if you are concerned with overdoing the bitterness, you can most easily delete the full 90-minute boil addition to reduce by about 9 IBU, knocking it down a couple notches on the human perception scale (humans can taste differences about ~4 IBUs at a time, so 9 IBU would literally be about "two notches"!).

 

[deeve007]

If you are using pellets, my own formula says it will be about 46 IBU. Very consistent with Brewfather.

I have changed the Brewfather recipe earlier today to lower IBU, I should have screenshot the original recipe, which had the same weight of hops as the Sierra Nevada recipe, halved for a 10L batch.

But yeah, I'm thinking about knocking that 90 minute addition on the head, it's not like I'll be brewing an exact mirror beer anyway, either way will be going for a "close as possible" oucome.

 

[dmtaylor]

I have changed the Brewfather recipe earlier today to lower IBU, I should have screenshot the original recipe, which had the same weight of hops as the Sierra Nevada recipe, halved for a 10L batch.

Ah... thank you for the clarification, I missed that. So OK, I've confirmed your later version of the recipe to hit mid 40s for IBUs, if that was your goal.

 

[VikeMan]

If Sierra Nevada is using late hop / whirlpool additions but ignoring this in a calculated value for IBUs, then their IBU calculation is incorrect. But they might also be measuring the real IBU value in a lab.

To be fair to Sierra Nevada, I don't know when exactly they tagged SNPA at 38 IBUS (or how), but I'm pretty sure SNPA predates the Tinseth, Rager, and Garetz formulae by more than a decade. So maybe it was a lab measurement (and what lab method back in the 80s?). Or maybe they estimated it some other way and it "stuck?" That said, my money would be on a brewery the size of Sierra Nevada knowing exactly what their flagship beer measures today.

As for estimating IBUs for post boil additions, to the best of my knowledge the first brewing program/sheet that appeared in was in 2013, and it was (is) based on the study done by Mark Malowicki. Sadly, some tools still don't do it, but I supect most of the popular ones do by now. I mean, technically, the Tinseth formula doesn't support it. Or it does, but computes 0, depending on how you want to look at it.

 

[Somesaymybeerisdrinkable]

It is my understanding IBU calculators are not accurate, but are useful. I would adjust the 90 minute addition until it is at a level you like based on similar beers you have made.

If you want to tryout another IBU calculator there is the SMPH method created by a homebrewer John-Paul Hosom

 

[HM-2]

The Sierra Nevada recipe reminds me of how much I hate it when people don't provide IBU numbers for their hops in addition to weights.

0.5oz of Cascade at 90 minutes could be 8 IBU, or it could be 14
0.75oz of Cascade at 60 minutes could be 11 IBU, or it could be 20
2oz of Cascade at 30 minutes could be 23 IBU, or could be 41
2oz of Cascade in the whirlpool is probably about 5 IBU but could be more or less.

I would guesstimate their recipe is supposed to be at or around 45 IBU and they're using relatively low AA (maybe 4.5%) whole cone Cascade. But if you got some 7.5%-8% stuff you could easily have an 80 IBU beer on your hands.