Incorrect IBUs in BeerSmith?

I've already posted this to the BrewSmith Forum, but figured that someone here might be able to explain what's going on faster.

The IBUs listed on the grid (33.3 + 10.1 + 9.2 + 3.9 + 2.5 + 5.4 + 6.0 + 5.5 = 75.9) don't sum up to the IBUs listed under bitterness (105.4) for my recipe. Any idea what is going on? I do have a late Extract addition.

Type: Extract Date: 12/17/2011
Batch Size (fermenter): 5.00 gal Brewer: Anthony B
Boil Size: 4.00 gal Asst Brewer:
Boil Time: 60 min Equipment: My Equipment
End of Boil Volume 3.64 gal Brewhouse Efficiency: 75.00 %
Final Bottling Volume: 5.00 gal Est Mash Efficiency 0.0 %
Fermentation: My Aging Profile Taste Rating(out of 50): 35.0
Taste Notes:
Ingredients
Ingredients

Amt Name Type # %/IBU
2 lbs Caramel/Crystal Malt - 40L (40.0 SRM) Grain 1 18.2 %
8.0 oz Special Roast (50.0 SRM) Grain 2 4.5 %
4 lbs 4.0 oz Extra Light Dry Extract (3.0 SRM) Dry Extract3 38.6 %
1.00 oz Columbus (Tomahawk) [13.30 %] - Boil 60.0 min Hop 4 33.3 IBUs
0.50 oz Columbus (Tomahawk) [13.30 %] - Boil 20.0 min Hop 5 10.1 IBUs
0.50 oz Simcoe [12.20 %] - Boil 20.0 min Hop 6 9.2 IBUs
4 lbs 4.0 oz Extra Light Dry Extract [Boil for 15 min](3.0 SRM) Dry Extract7 38.6 %
0.50 oz Amarillo Gold [8.50 %] - Boil 10.0 min Hop 8 3.9 IBUs
0.50 oz Cascade [5.50 %] - Boil 10.0 min Hop 9 2.5 IBUs
0.50 oz Chinook [11.80 %] - Boil 10.0 min Hop 10 5.4 IBUs
0.50 oz Columbus (Tomahawk) [13.30 %] - Boil 10.0 min Hop 11 6.0 IBUs
0.50 oz Simcoe [12.20 %] - Boil 10.0 min Hop 12 5.5 IBUs
2.0 pkg Dry Ale Yeast (Fermentis #Safale US-05) [50.00 ml] Yeast 130.50
oz Amarillo Gold [6.90 %] - Dry Hop 7.0 Days Hop 14 0.0 IBUs
0.50 oz Cascade [5.50 %] - Dry Hop 7.0 Days Hop 15 0.0 IBUs
0.50 oz Chinook [11.80 %] - Dry Hop 7.0 Days Hop 16 0.0 IBUs
0.50 oz Columbus (Tomahawk) [13.30 %] - Dry Hop 7.0
Days Hop 17 0.0 IBUs
0.50 oz Simcoe [12.20 %] - Dry Hop 7.0 Days Hop 18 0.0 IBUs

Beer Profile
Est Original Gravity: 1.077 SG Measured Original Gravity: 1.086 SG
Est Final Gravity: 1.018 SG Measured Final Gravity: 1.019 SG
Estimated Alcohol by Vol: 7.8 % Actual Alcohol by Vol: 8.9 %
Bitterness: 105.4 IBUs Calories: 297.5 kcal/12oz

Thanks,
Anthony

I dunno, are you missing one? It's a possibility there is a bug in the software, and that it recalculated one or the other IBUs when you changed the batch size, or timing of extract additions, or something like that.

I think the difference in this case is negligible, as difficult as that may be to believe. You aren't really throwing in a lot of late HUGE hops additions, and it's a black IPA (I assume) that is touting enough IBUs that most people cannot really taste the difference anyway.

Also, 2 lbs of crystal malt in there definitely seems like way too much. You will probably have attenuation problems. I would try more like 1 pound and make up the difference with base malt/extract.

I too have noticed that brewing software is often times incorrect with IBUs as well as extract efficiency of malt and attenuation of yeast. We have to understand that brewing software, while a very useful tool, it should be used simply as an estimation.

Hops do not always yield the same alpha acids from crop to crop. For instance: my 1 pound bag of magnums I bought on 12-14-2011 are labeled as providing 10% alpha acid. The last 1 pound bag of the same hops I bought from the same distributor were labeled at 14% alpha acid. The same could be said for base malts. The maltster may not have malted the grains exactly the same and the crop may provide different yields of a-amylase and starches. Yeast can mutate from culture to culture depending on how many generations of said culture may have been harvested. If your distributor has not kept the yeast at optimal temps or the strain is too old it may not flocculate or attenuate the way you expect. The only true way to determine the actual yields of your particular ingredients is to brew with them and keep extensive notes. Also make sure to dial in brew house efficiency and brew over and over with those ingredients. Then you can learn to make adjustments while using brewing software.

weirdboy said:

I dunno, are you missing one? It's a possibility there is a bug in the software, and that it recalculated one or the other IBUs when you changed the batch size, or timing of extract additions, or something like that.

I think the difference in this case is negligible, as difficult as that may be to believe. You aren't really throwing in a lot of late HUGE hops additions, and it's a black IPA (I assume) that is touting enough IBUs that most people cannot really taste the difference anyway.

Also, 2 lbs of crystal malt in there definitely seems like way too much. You will probably have attenuation problems. I would try more like 1 pound and make up the difference with base malt/extract.

Click to expand...

I'm pretty sure that I'm not missing anything; I copied and pasted from the software directly.

Is a 33% difference negligible? (Honestly, I'm curious.)

I generally add a lot of additional crystal malt because I like a little more caramel and body to beer and because many of the home brews that I have tasted are a little thin for my taste. With regard to attenuation problems I assume you mean excess residual sugars?

I'd say it's a little bit more of an Imperial IPA rather than a black one, but I made up the recipe so who's to say. Doesn't black IPA usually have some Black Patent malt?

Thanks,

Anthony

Just by chance. I've been reading " Designing great beers" and read the hops section last night. A difference of less than 5 IBUs is not dectable by the human palate. 33% you probably will detect. I assume, since your question is well thought out, that you are an experienced brewer. You probably know that the first oils to be isomerized are the aroma oils, which then dissapate, followed by the flavor oils, which dissapate, followed by the bittering oils. If you want to boost the IBUs, either increast the early additions quantity or extend the boil. The brewing software should show you the likely combination that will hit your target IBU numbers. Also, be sure to plug in the actual Alpha acid content from the hopps. The numbers used by the software are "average" for that particular variety, and can help you with your initial selections. The actuals vary from crop to crop, which is why they are printed on each hop package. When I brew a recipie, I always record the target IBUs ( from the recipie) and the actual AA content of each hops (fron the hopps package). I then use a beer calculator to adjust the hops quantity and timing to hit the target IBUs.

william_shakes_beer said:

Just by chance. I've been reading " Designing great beers" and read the hops section last night. A difference of less than 5 IBUs is not dectable by the human palate. 33% you probably will detect. I assume, since your question is well thought out, that you are an experienced brewer. You probably know that the first oils to be isomerized are the aroma oils, which then dissapate, followed by the flavor oils, which dissapate, followed by the bittering oils. If you want to boost the IBUs, either increast the early additions quantity or extend the boil. The brewing software should show you the likely combination that will hit your target IBU numbers. Also, be sure to plug in the actual Alpha acid content from the hopps. The numbers used by the software are "average" for that particular variety, and can help you with your initial selections. The actuals vary from crop to crop, which is why they are printed on each hop package. When I brew a recipie, I always record the target IBUs ( from the recipie) and the actual AA content of each hops (fron the hopps package). I then use a beer calculator to adjust the hops quantity and timing to hit the target IBUs.

Click to expand...

I appreciate the feedback. The AA numbers I inserted are the ones from the packets. My concern is that the individual IBU contributions (as shown by the software) of each hop addition sum to a total which is far lower than the total IBUs listed by the software and I don't know which number is correct.

its probably related to the boil size vs batch size. about 100IBUs is considered the max saturation and since this is a partial boil, you'll be closer to the 75.9 IBUs. btw, that evap rate can't be correct - less than 2qts in an hour?

+1 to cutting the crystal down. extract already contains some carapils so 2lbs of crystal on top of that is excessive, especially in an IPA.

squirrelly said:

I too have noticed that brewing software is often times incorrect with IBUs as well as extract efficiency of malt and attenuation of yeast. We have to understand that brewing software, while a very useful tool, it should be used simply as an estimation.

Click to expand...

i've noticed that too. sometimes my software gives me things like 55.6 IBU from a dry hop add, for instance.

weirdboy said:

I think the difference in this case is negligible, as difficult as that may be to believe. You aren't really throwing in a lot of late HUGE hops additions, and it's a black IPA (I assume) that is touting enough IBUs that most people cannot really taste the difference anyway.

Also, 2 lbs of crystal malt in there definitely seems like way too much. You will probably have attenuation problems. I would try more like 1 pound and make up the difference with base malt/extract.

Click to expand...

both of these! when i brew beers over 100 IBU, i really stop worrying about IBU and focus on the flavor/aroma compounds going into the beer.

that seems to be way too much crystal/caramel for a CDA (assuming by recipe). i have a CDA fermenting now, og 1.067, with .75# crystal 10 and i'm wondering if i went overboard with that. 2# of caramel malt will definitely leave you one sticky brew, IMO.

That's not a black IPA recipe... there are no dark malts in it!

Anyway, I checked some recipes on my BeerSmith 2.0, and the calculations match for my all grain/full boil batches, but differ for my partial mash/partial boil batches. So it probably has to do with how the software adjusts the bittering calculations to compensate for top off water.

ArcaneXor said:

That's not a black IPA recipe... there are no dark malts in it!

Anyway, I checked some recipes on my BeerSmith 2.0, and the calculations match for my all grain/full boil batches, but differ for my partial mash/partial boil batches. So it probably has to do with how the software adjusts the bittering calculations to compensate for top off water.

Click to expand...

just looked back at the op, i saw special roast and my brain thought roasted barley. i've got CDA on the brain!

i still think that's an a$$load of caramel malt.

So if I change the boil time of my late extract add, the individual line item IBU numbers do not change but the Bitterness (IBUs) change. It looks like adjustments for late extract adds are not reflected on the individual ingredient lines.

NordeastBrewer77 said:

just looked back at the op, i saw special roast and my brain thought roasted barley. i've got CDA on the brain!

i still think that's an a$$load of caramel malt.

Click to expand...

Holy crap you're right. I thought it said roasted barley too.

Is a 33% difference negligible? (Honestly, I'm curious.)

Click to expand...

No, not normally. But when you are talking about a recipe that is already 75+ IBUs, you are getting pretty close to the limit of what the human palate can distinguish. Which is why I said in this particular case the difference is negligible. If it was going between 40 and 60 IBUs, then you'd have a more serious issue.

weirdboy said:

Holy crap you're right. I thought it said roasted barley too..

Click to expand...

too funny! it's an addictive style, hard not to think about a tasty CDA from time to time. i'm thinking with the roasted barley and all that caramel, a barley wine or or maybe a really big red (those are addictive too)