IBU confusion with beer kit

[AleL0ver]

I bought this kit, according to the instructions the IBU is 30-33, now if I use the IBU calculator it comes out with an IBU of 21.
I played around with the numbers and the kit recipe calls for a boil volume of 2.5 gal, if I replace the volume with 5 gal in the IBU calculator then the IBU is 31, is that the issue here, the kit assumes my boil volume is 5 and not 2.5 gal?

Thanks

 

[dneubeck85]

Read the brew tips section and your question is answwreed

 

[AleL0ver]

I did, that is just the thing, I input all the values and the IBU came out to 21 when using the calculator, so the instructions dont match up??

 

[twistr25]

The kit probably(possibly) assumes you are doing a full boil. You get better hop utilization with more water, so it stands to reason that using half the water you'll get less utilization.

 

[AleL0ver]

The kit instruction read as follows...

3. STEEP GRAINS
Pour 2.5 gallons of clean water into your brew pot and begin to heat
1. Pour
crushed grains into grain bag and tie a loose knot at the top of the bag
2. When
the water is within an appropriate steeping temperature (150º - 165ºF) place the
grain bag into the brew pot
3. Steep grains for approximately 20 minutes. Remove
grain bag and without squeezing, allow liquid to drain back into brew pot. Your
water is now wort.

 

[twistr25]

Does it say to add more water before the boil, that's just for steeping?

Or perhaps they made the mistake and just calculated the IBUs off of a full boil and wrote the instructions for a partial.

 

[EvilDeadAsh]

What are the AAU of the hops you received? The ingredients are just listed as "bittering, flavoring, and aroma" with no indication. Its possible the brewersfriend.com calculator is making assumptions on general AAU values, and the AAU of the hops you received are higher or lower than that average.

That said - the calculator is probably accurate to the numbers you are giving it, but you likely won't notice a significant difference in the finished product from a difference of 9 IBU.

 

[AleL0ver]

No additional add of H20 after steeping, I think I will need to do a full boil unless I read it wrong?

AAU is 4.9 as per packet (US Golding), I put that in the calculator as well

After steeping it says...
4. START BOIL
Bring your wort to a gentle, rolling boil. Add all of the included LME and DME
to the boiling wort
Continuously stir the extract into the wort as it returns to a
gentle, rolling boil

 

[gcdowd]

Could also be a different scale being used to calculate (rager, tinseth)

 

[menerdari]

I have brewed several Brewers Best kits and they do intend for you to boil 2.5 gallons and top off in the fermentation bucket.
They probably calculated it wrong.
I brewed their American pale ale and it is one tasty beer, I really like it a lot. I bet your English version will be very similar.

 

[Revvy]

More than likely two different hop formulas are at play, yours and whatever the one used to create the recipe is set at. There's several different formulas, and some software defaults differently than others.

It doesn't really matter. In a lot of ways they're arbitrary numbers anyway. Once you'll listen to this John Palmer podcast you'll see what I mean.

Basic Brewing Radio

March 20, 2008 - What Is an IBU . . . Really?
John Palmer, author of How to Brew, shares information from a conference that challenged his concept of what defines an International Bitterness Unit (IBU).
Clicky to listen mp-3

Just brew the beer, it's not going to be any more or less hoppy no matter whether it's in your software or in their recipe. It will be whatever it's meant to be.

 

[larrybrewer]

At Brewer's Friend, on the recipe editor, click the More... button, from there you can choose what IBU equation you want to use. I wonder if the Tinseth or Rager equation provides a different value?

It could also be the AA value from a few years ago is higher than today. I've seen changes as much as 3.5%, which is a lot when it comes to a delicate beer around 30. Try fiddling with either the equation, or the hop AA value, and I bet you can get closer to 31.

If you really want it to be higher in IBU, split the fermentables in half, add the first half as normal at the start of the boil, and do a late addition for the second half. A lower boil gravity translates into higher hop utilization.

 

[freisste]

A lower boil gravity translates into higher hop utilization.

I don't think that is true...

It was long believed, but I think it is generally accepted as a myth.

 

[beerman0001]

Most of the kits originated as all grain then transfered over to DME/LME + steeping grains. The IBU are based on a full boil.

 

[larrybrewer]

I don't think that is true...

It was long believed, but I think it is generally accepted as a myth.

From Palmer:
"hop utilization decreases with increasing wort gravity."
http://www.howtobrew.com/section1/chapter5-5.html

I'd guess Palmer's information and the Tinseth equation are getting a bit dated, but I'd still be very hesitant to dismiss their results off hand without some numbers to back it up.

 

[freisste]

From Palmer:
"hop utilization decreases with increasing wort gravity."
http://www.howtobrew.com/section1/chapter5-5.html

I'd guess Palmer's information and the Tinseth equation are getting a bit dated, but I'd still be very hesitant to dismiss their results off hand without some numbers to back it up.

Admittedly, I have no numbers, but I believe Palmer himself has come out and said he was wrong. Again, I don't have a source to cite and you are more than welcome to believe whatever you would like. (In fact, while Palmer doesn't believe wort gravity has a direct effect on hops utilization, he does mention a possible indirect effect caused by hot break.)

 

[EvilDeadAsh]

Yooper talked to him in person and has corrected this in a few threads, like this one.

 

[freisste]

Yooper talked to him in person and has corrected this in a few threads, like this one.

Thanks for the source. I was kinda going from memory.

 

[larrybrewer]

Yes, thanks for the source, interesting information to review there.

 

[Revvy]

It's also in the podcast i posted earlier in this thread.

 

[freisste]

Revvy

Great pic. Go Tigers! (I'm from Ann Arbor...)