Hop IBU question

[gmiller598]

Ok, I'm going through the BrewDog DIY Dog manual and I'm studying their Punk IPA recipe. The recipe says that it is 40 IBU but when I read the complete list of hops, I can't figure out for the life of me how the IBU can come to that number.

When I enter in all the hops into Beersmith, it tells me the IBU is 88.7 with over 11 oz of hops being used. If the recipe is correct, how does the beer actually exists in the range of 40 IBU with that amount of hops used? Using .71 oz, or 20 g of Chinook at 13% at the start of the boil equates to 31.2 IBU on its own.

Is the recipe wrong or is there something I'm missing about how IBU is calculated?

 

[dmtaylor]

I see your point.... however the recipe is probably not wrong. It's really just that the calculation methods tend to over-estimate IBUs. IBUs are measured in a laboratory, not calculated. So, if the brewery tells you the beer has 40 IBUs, then by-golly, they're probably right as they probably measured that in a lab.

How to resolve this? Brew the recipe the way they tell you. Your calculator might say 89 IBUs...... but in reality, it might only give you 40 or 50 IBUs. Might taste like 89 IBUs to your palate...... but again, in real life, it's not that much when you measure it in a lab. Our calculators are all F'ed up, honestly. They're all wrong. All of 'em.

 

[BobBailey]

Since they list hop additions as start, middle, end and dry hop and don't give Alpha acid % for the hops, a lot of playing around is needed. Not something I would recommend for a novice brewer. You would need to know the AA% of each of the hop varieties as available to you and determine the techniques and timing of additions as well.

Read up on late hopping techniques and don't limit yourself to the belief that start, or bittering, additions need to be added at the beginning of the boil.

I remember all too well the urge to rush into brewing the more advanced recipes. Do yourself a favor and get the process down by brewing simpler recipes first. Once you are comfortable with the process do a bunch of reading on techniques you are not familiar with. You will be rewarded by your patience.

 

[gmiller598]

Since they list hop additions as start, middle, end and dry hop and don't give Alpha acid % for the hops, a lot of playing around is needed. Not something I would recommend for a novice brewer. You would need to know the AA% of each of the hop varieties as available to you and determine the techniques and timing of additions as well.

Read up on late hopping techniques and don't limit yourself to the belief that start, or bittering, additions need to be added at the beginning of the boil.

I remember all too well the urge to rush into brewing the more advanced recipes. Do yourself a favor and get the process down by brewing simpler recipes first. Once you are comfortable with the process do a bunch of reading on techniques you are not familiar with. You will be rewarded by your patience.

Well, I'm not exactly a complete beginner as I've been doing it for a few years now but this will actually be my first attempt at an IPA however. While I'm obviously trying to replicate what they make. I'm fine with experimenting little bit to find what works for me and what doesn't.

That being said, I purchased my hops this evening and the alpha and beta acids don't match what is in Beersmith so tweaking that a bit and playing around with my hop additional are certainly getting me closer to the target.

 

[IslandLizard]

Well, I'm not exactly a complete beginner as I've been doing it for a few years now but this will actually be my first attempt at an IPA however. While I'm obviously trying to replicate what they make. I'm fine with experimenting little bit to find what works for me and what doesn't.

That being said, I purchased my hops this evening and the alpha and beta acids don't match what is in Beersmith so tweaking that a bit and playing around with my hop additional are certainly getting me closer to the target.

Just edit the hop profiles in BS to reflect the %AA and %BA of the ones you have. After that, you will have to pull the hops up in the recipe again and re-assign to the "modified" ones. BeerSmith won't update recipes automatically.

 

[unixuser101]

Yep I did that recipe on Saturday and your correct the IBUs and EBC don't tally.

I assumed that the hops havent been scaled down from the 50 Ltr test Brewdog setup. I halved them and adjusted the flavour hops to 15 minutes rather then 30 minutes and up scaled for my 25 Ltr into the fermentor setup I have.

The dry hoppping regime looks a bit OTT as well. Assumed that is for 50 Ltrs as well. So will halve them as well.

There are lots of errors in other recipes as well. Decimel points in the wrong place or numbers missing. Or obvious ingredients missing.

Still it was great for them to have open sourced the recipes. I shall be brewing another 2 this weekend.

 

[lolcats]

I always found that the calculators over estimate the IBUs.

 

[gmiller598]

Yep I did that recipe on Saturday and your correct the IBUs and EBC don't tally.

I assumed that the hops havent been scaled down from the 50 Ltr test Brewdog setup. I halved them and adjusted the flavour hops to 15 minutes rather then 30 minutes and up scaled for my 25 Ltr into the fermentor setup I have.

The dry hoppping regime looks a bit OTT as well. Assumed that is for 50 Ltrs as well. So will halve them as well.

There are lots of errors in other recipes as well. Decimel points in the wrong place or numbers missing. Or obvious ingredients missing.

Still it was great for them to have open sourced the recipes. I shall be brewing another 2 this weekend.

After adjusting the acids in Beersmith, I have the initial addition at 60, the middle at 15, and the end going at flameout while the dry hop stays the same. That got me into the right ballpark with the IBUs. Still a touch higher than indicated but a lot closer.

I'll give it a try making it this way and do a side by side comparison with the real stuff and see how close I can get.

 

[unixuser101]

Let us know how you get on adding all that dry hop and how it compares to the real Punk IPA.

I went for a more modest 100g, I just halved and rounded to nearest sensible number so I am adding 25,20,20,20,10 & 5

Good luck, hope that 190g of dry hop dosnt make it too grassy. Ok 5 days at 14C will need to adjust my fermentation chamber.

u101