IBU calculation help

[Riverevir]

Hi All,

I just completed a third brew, and I'm hoping to get some help in calculating the IBU's. As a result, here comes my first post seeking help...

I brewed "Dead Ringer" from NB and the Centennial I used were 9%AA. The partial boil calls for 2.5 gallons of water plus the extract after the specialty grains are added until 170. 1 ounce at 60, 1 ounce at 20. I saved the 2 ounces for flameout and whirlpooled them. I read a bit on late hop additions and thought I would try this as the bitterness addition didn't seem to matter. Now I feel like this may have been bad instinct?

If I use a hop utilization chart with the OG reading (1.067), the IBUs come out to 43 on a 5 gallon batch. Using the calculator on Brewer's Friend website, which factors in a partial boil and batch the IBUs are closer under 30. If I add the 5 minute hop back in it's still showing at 34, which seems under style guidelines

The smell coming out of the airlock is very hoppy after a few days of fermentation. The aroma seems like it will be there even before the dry hop. I'm less worried about it being a "ruined batch" and more curious so I don't make the mistake again. Any help clarifying what I've got for an IBU calc? Every place I input seems to be a bit different.

 

[cswis86]

In my experience IBUs can be really difficult to accurately calculate. So much so that I only use online calculators as a rough estimate. 2 beers can have the same calculated IBUs and have a completely different perceived bitterness based on the variety of hop, malt, yeast, and water used in brewing. You beer will definitely taste fine but my not have the bitterness level you hoped. Once you drink the finished beer you can determine if you want to add more or less hops or change the hop schedule the next time you brew. Use the calculator as a reference point. If you calculated you have 43 IBUs from this beer and that's not enough you can up it 10-20 IBUs next time.

I have found that flameout or whirlpool hop additions do add some bitterness even though calculators count them as 0 IBUs. I've also found that beer will lose some bitterness during fermentation so recently I've upping my calculate IBUs by 15-20% to account for this loss. For instance if I want a beer with a finished IBU of 60 I've been adding enough to get to a calculated IBU of 75.

My best advice is to take good notes and tweak your recipes to achieve the flavors and bitterness you want. You never brew your best beer the first time! You need to brew the same beer over and over to get it right.

 

[mredge73]

I plugged it into my favorite recipe builder (Brew Mate) and got 45 IBU.
It doesn't calculate partial boil. I know hops are under utilized on a partial boil but I wouldn't expect it to loose as much as 30% as the brewer's friend suggests.
I would say that it probably somewhere between 34 and 45; as far as taste goes there isn't much difference between the two anyway.
Resulting beer should still be drinkable but it is far from a IPA.

 

[Silver_Is_Money]

If you boiled only 2.5 gallons (vs. the typical 7 for an all grain batch yielding ~5.6 gallons in the fermenter), then I'm calculating that your hop utilization is only about 45% of what it would have been for a 7 gallon boil.

If you were shooting for 40 IBU's based upon 7 gallons boiled then you should hit about 18.5 IBU's if you only boil 2.5 gallons into which the hops are added.

But IBU's are likely +/- about 33% to begin with, so you may end up with anywhere between roughly 14 and 26 IBU's. But the greater likelihood is to end up on the low side of the midrange vs. the high side, so best bet is in the neighborhood of 14 to 18.5 IBU's.

 

[mredge73]

If that is the case your bittering is in the BMC range. I never realized how crippling a partial boil can be to your hop utilization, haven't done one in many years.
The hop aroma and flavor will cover up some of the sweetness via perceived bitterness if you drink it quickly. Once the aroma fades this beer will be hard to drink.

Going forward, I would advice you to find a good recipe building software that can handle partial boils and plan your brew with in prior to ordering.
If you continue to do partial boils it looks like you will need to double up your bitter charge from now on. AA% on hops degrade over time, some hops degrade faster than others and storage condition also plays a huge role.
So nailing an exact IBU through recipe formulation isn't really possible, but you can get close using fresh ingredients.

 

[Riverevir]

Thanks for the replies - the comments regarding the inefficiency of a partial boil make sense. The batch is 5 gallon which should bump the the IBU a bit from your calculation but it won't be a massive increase. Disappointing because the aroma is very good at this point before I dry hop but I guess that's why IBUs are a bit incomplete on measuring hops in the final product.

Any thought to extra ounce of dry hops to cover up the low IBUs ? At this point I'm not sure it matters a ton but I appreciate any suggestions/comments

 

[Silver_Is_Money]

IBU's are only reduced by about 16% if 5 gallons are being boiled along with the hops (instead of the more typical 7 gallons).

 

[mredge73]

One ounce won't do much, if you are going to put it in do it now.
It certainty won't hurt anything, may even increase the perceived bitterness for a little while.
You will need to drink this beer young, as soon as it is finished fermenting in a few more days bottle it.
Don't waste any time with a secondary.

The 20 minute addition that you did adds a lot of flavor but little bitterness, Centennial is fruity.
I would expect this beer to taste like a grapefruit after it sits for a while and the hop aroma dissipates.
Let us know how it goes and good luck.

 

[Riverevir]

Sorry I guess I need to rephrase. The boil volume you listed was correct at 2.5 gallons, but the final batch size was 5 gallons as opposed to the 5.6 you list.

To further complicate my issue of IBU calculation, I may have inadvertently helped myself with a small boost. I've read one issue with extracts is a longer boil leads to a darker color than intended. One work around to this is that you add most of the syrup later in the boil. In my case I added 3lbs of syrup at boiling with with 60 minute hop addition. The remaining 6.1 lbs of syrup didn't get added until the 20 minute hop addition. So at least the initial 40 minutes of the boil was done at a lower gravity. If I'm understanding the problems with a partial boil correctly (thicker liquid that is harder for the hops to boil into) this would likely have given me a bit better utilization earlier in the boil. For whatever that's worth *shrug*...

Ultimately the idea of noting the bitterness and adjusting to taste is something I will have to do a bit of as I learn. The way I approached this at least helped me understand the disadvantages of partial boils and I hope to still have decent beer in a few weeks.

 

[Silver_Is_Money]

The way you did it your IBU situation will not be as dire as 18, but it will not be 40 either. Something inbetween.

 

[Yooper]

Sorry I guess I need to rephrase. The boil volume you listed was correct at 2.5 gallons, but the final batch size was 5 gallons as opposed to the 5.6 you list.

To further complicate my issue of IBU calculation, I may have inadvertently helped myself with a small boost. I've read one issue with extracts is a longer boil leads to a darker color than intended. One work around to this is that you add most of the syrup later in the boil. In my case I added 3lbs of syrup at boiling with with 60 minute hop addition. The remaining 6.1 lbs of syrup didn't get added until the 20 minute hop addition. So at least the initial 40 minutes of the boil was done at a lower gravity. If I'm understanding the problems with a partial boil correctly (thicker liquid that is harder for the hops to boil into) this would likely have given me a bit better utilization earlier in the boil. For whatever that's worth *shrug*...

Ultimately the idea of noting the bitterness and adjusting to taste is something I will have to do a bit of as I learn. The way I approached this at least helped me understand the disadvantages of partial boils and I hope to still have decent beer in a few weeks.

Even though the IBU calculators take the SG of the boil into account, it really has very little impact on the isomerization of the hops oils. What really has the most impact is the dilution factor of a partial boil.

First, it's important to note that the most IBUs you can get to isomerize is less than 100 IBUs before the wort is saturated with hops oils and not able to isomerize. Even some of the hoppiest beers have been lab tested, and are about 80-85 IBUs when they calculate out to 250+.

Even if you were able to get 100 IBUs in your 2.5 gallon boil (not likely, but for the same of argument and my bad math skills), when you add 2.5 gallons of 0 IBU water to the wort, you immediately halve the IBUs.

Like this: 2.5 gallons of 100 IBUs + 2.5 gallons of 0 IBUs= 5 gallons of 50 IBUs. Again, getting 100 IBUs is unlikely, so it'd be more like 70 or 80 if a ton of hops were used. That means, just by adding water, you'd end up with 35-40 IBUs as a max.

The fix it to boil as much as you reasonably can, and if necessary consider using Hopshot or one of those hops extracts for bittering.

 

[Riverevir]

Foam dropped off in the last 24 hours. FG is pretty well right on the mark so I dropped in the dry hops. Definitely is under-bittered but figured I'd post an update and some pics for those who offered me some help.

Learned a lesson thanks to everyone here. Hopefully someone who is new reads this and learns to bump their hop additions if they plan to partial boil!

Yes... in spite of lower than intended IBUs it is still beer. Clocking in at about 7.2% ABV and the lack of bitterness just means I'll have to take it easy.View attachment ImageUploadedByHome Brew1491268818.447625.jpgView attachment ImageUploadedByHome Brew1491268829.047583.jpg

 

[Silver_Is_Money]

Foam dropped off in the last 24 hours. FG is pretty well right on the mark so I dropped in the dry hops. Definitely is under-bittered but figured I'd post an update and some pics for those who offered me some help.

Learned a lesson thanks to everyone here. Hopefully someone who is new reads this and learns to bump their hop additions if they plan to partial boil!

Yes... in spite of lower than intended IBUs it is still beer. Clocking in at about 7.2% ABV and the lack of bitterness just means I'll have to take it easy.

Where did you purchase the Fermonster with the bottom discharge valve? I like the idea!!!

 

[Riverevir]

MoreBeer has them in 7 and 6 gallon capacities. Buying two gets you over the free shipping threshold very easy. https://www.morebeer.com/search?search=fermonster

I got the 7 (more capacity seemed better) before I read about headspace and oxidation but if I can get a better pipeline set up I'll just go to secondary fermentation more often... after reading enough about secondaries and their benefits I decided to do primary only until it screws me. Less equipment the better for a new brewer.

 

[Silver_Is_Money]

MoreBeer has them in 7 and 6 gallon capacities. Buying two gets you over the free shipping threshold very easy. https://www.morebeer.com/search?search=fermonster

I got the 7 (more capacity seemed better) before I read about headspace and oxidation but if I can get a better pipeline set up I'll just go to secondary fermentation more often... after reading enough about secondaries and their benefits I decided to do primary only until it screws me. Less equipment the better for a new brewer.

Excellent. Thank you! My local shops don't sell the Fermonster with the bottom valve.

 

[neverfadeaway86]

Brewers friend has a spot to where you can add boil size and batch size into it, so if you boiled 2.5 gallons you would put that amount for boil size and then put 5 gallons as batch size and it should calculate the batch with the addition of the non hopped water

it also has a spot for a whirlpool addition