How many IBU's do I gain/lose when using....

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emgesp1

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only half the LME before the beginning of the boil and the other half at 15 minutes left of boil?


I'm getting about 58 IBU's with my recipie if I were to use all the 8lbs of malt extract pre-boil.

I start off with 3.5 qallons of water, but by the time hops are added about half a gallon has evaporated.
 
eriktlupus said:
according to beersmith you'll increase your ibus by doing a late addition
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By a good number? I want to stay within the style which is listed to have 60 IBU's max.

Maybe, I should add half oz of the total 2oz Chinook at 45 minutes left of boil, just to decrease the IBU's a bit.
 
The maximum threshold of IBUs in a given batch of beer is 100, anything over that is only adding to flavor (and head retention and mouthfeel). This maximum number is also only in worts of around 1.050. Now if you are boiling 3 gal down to about 2.5, and adding 2.5 gal of wort, then your maximum is already sliced down to 50 IBUs in a batch, and that is still with a wort gravity of 1.050 or below.

Now, with a full boil if you are trying to reach a final gravity 1.050, then you will have near 100% efficiency when it come to alpha acid isomerization and IBU absorption, and you can reach the 100 IBU mark, since you would be starting the boil around 1.044. When using LME, this will be about 7 lbs. If you put 7 lbs of LME into only 3 gallons of wort, then you are starting with a pre boil gravity of 1.084, boiling down to probably around 2.5gal at 1.100 before topping of with water to reach your OG of 1.050. Far above the ideal IBU efficiency gravity. This will leave you with a wort that has a max IBU rating of approx. 82.7, not too bad, but wait. After topping off, you will have only 41.4 IBUs.

So without doing a late extract addition you maximum IBU level would be 41.4, not quite the hop bomb you may have thought you were making.

Now, if you add say, half at the end, lets see what that does. Your pre boil gravity will be around 1.042 (very close to that of a full wort boil), and you will boil off around to about 2.5 gal at 1.050, perfect. So now you have 100 IBUs, top off and you are at you maximum of 50 IBUs, still not the hop bomb you thought, but better. If you are only adding 2 gal of top off water, then you max IBU will be 60, 1.5 gal and the max IBU is 70, 1 gal is 80, .5 gal is 90 and not topping off can get you the maximum IBU level of 100.
 
BarleyWater said:
The maximum threshold of IBUs in a given batch of beer is 100, anything over that is only adding to flavor (and head retention and mouthfeel). This maximum number is also only in worts of around 1.050. Now if you are boiling 3 gal down to about 2.5, and adding 2.5 gal of wort, then your maximum is already sliced down to 50 IBUs in a batch, and that is still with a wort gravity of 1.050 or below.

Now, with a full boil if you are trying to reach a final gravity 1.050, then you will have near 100% efficiency when it come to alpha acid isomerization and IBU absorption, and you can reach the 100 IBU mark, since you would be starting the boil around 1.044. When using LME, this will be about 7 lbs. If you put 7 lbs of LME into only 3 gallons of wort, then you are starting with a pre boil gravity of 1.084, boiling down to probably around 2.5gal at 1.100 before topping of with water to reach your OG of 1.050. Far above the ideal IBU efficiency gravity. This will leave you with a wort that has a max IBU rating of approx. 82.7, not too bad, but wait. After topping off, you will have only 41.4 IBUs.

So without doing a late extract addition you maximum IBU level would be 41.4, not quite the hop bomb you may have thought you were making.

Now, if you add say, half at the end, lets see what that does. Your pre boil gravity will be around 1.042 (very close to that of a full wort boil), and you will boil off around to about 2.5 gal at 1.050, perfect. So now you have 100 IBUs, top off and you are at you maximum of 50 IBUs, still not the hop bomb you thought, but better. If you are only adding 2 gal of top off water, then you max IBU will be 60, 1.5 gal and the max IBU is 70, 1 gal is 80, .5 gal is 90 and not topping off can get you the maximum IBU level of 100.
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Hmmm, hate to say this, but this is too much information, but thank you it's still very helpfull.

I'm boiling 3.5 gallons of water. I have about 2.5 lbs of steeping grains and 8lbs of LME. I'm using 2 oz of Chinook at 12% AA at 60 minutes, and I'm adding half oz of Cascade at 6% AA at 15 minutes left of boil.

So, if I add half of the LME pre-boil and the rest 15 minutes left of boil, how many IBU's should I expect.

Lastly, if fermentation goes right, will I not reach a 6% ABV if I use 8lbs of LME?
 
OK, you're targeting an OG of about 1.059. With a boil of 3.5 gallons, you can probably expect to be adding 2-2.5 gallons of top off water to the fermenter. The gravity of your boil will be about 1.043 if you only add half the extract at the beginning, boiling down to a gravity of about 1.060 before adding the rest of the malt, so will get the majority of the bittering potential from the hops. You are almost maxing out the bittering potential of your boil at 100, so, if you are adding 2.5 gallons to top off, you will get about 50 IBUs, 2 gallons will get you about 60 IBUs.
 
BarleyWater said:
OK, you're targeting an OG of about 1.059. With a boil of 3.5 gallons, you can probably expect to be adding 2-2.5 gallons of top off water to the fermenter. The gravity of your boil will be about 1.043 if you only add half the extract at the beginning, boiling down to a gravity of about 1.060 before adding the rest of the malt, so will get the majority of the bittering potential from the hops. You are almost maxing out the bittering potential of your boil at 100, so, if you are adding 2.5 gallons to top off, you will get about 50 IBUs, 2 gallons will get you about 60 IBUs.
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Thanks

Why does the beer recipator say that my SG will be 1.101 boiling 3.25g of water, and that after top off to expect 1.066 with the grains I'm using?
 
Well, you must not be telling it that half the extract won't be getting boiled, and I don't know. I put you at 1.066 if you only end up with 4.5 gallons of water, but as long as you are shooting for 5 gallons, it's going to be about 1.059. And don't trust that thing on what it tells you for IBUs, most programs lie about IBUs when it comes to ranges above 100 and to partial boils.
 
BarleyWater said:
Well, you must not be telling it that half the extract won't be getting boiled, and I don't know. I put you at 1.066 if you only end up with 4.5 gallons of water, but as long as you are shooting for 5 gallons, it's going to be about 1.059. And don't trust that thing on what it tells you for IBUs, most programs lie about IBUs when it comes to ranges above 100 and to partial boils.
Click to expand...


So, will that possibly get me a 6% ABV beer if everything goes well during fermentation?
 
BarleyWater said:
Well, you must not be telling it that half the extract won't be getting boiled, and I don't know. I put you at 1.066 if you only end up with 4.5 gallons of water, but as long as you are shooting for 5 gallons, it's going to be about 1.059. And don't trust that thing on what it tells you for IBUs, most programs lie about IBUs when it comes to ranges above 100 and to partial boils.
Click to expand...

Is there a free calculator, or tool that is easy to use? I mean I have John Palmer's book, and it has a great chapter on calculating IBU's, but if there is an easier way to do it, why not.
 
I use Beer Smith, it has a free trial, and you may want to shell out for it once you try it out, I love it and couldn't imagine make a batch of beer without it or something similar. Also, Ray Daniels book Designing Great Beers is also a great place to figure out how to do a lot of different calculations, and a great resource on how to craft your own recipe.

EDIT: Even Beer Smith has the same IBU calculation problems.
 
BarleyWater said:
I use Beer Smith, it has a free trial, and you may want to shell out for it once you try it out, I love it and couldn't imagine make a batch of beer without it or something similar. Also, Ray Daniels book Designing Great Beers is also a great place to figure out how to do a lot of different calculations, and a great resource on how to craft your own recipe.

EDIT: Even Beer Smith has the same IBU calculation problems.
Click to expand...

Thanks for all your help. I greatly appreciate it.

This what I love about homebrewing, it's a less cocky hobby and everyone is helping others to become better brewers.
 
Like I said, Beer Smith, and every other calculator that I have come accross, don't account for the fact that you can only get 100 IBUs in a batch, nor does it account for the dillution in partial boils, just the increased boil gravity. You can figure it out, it just takes some extra working of the numbers.

If the maximum amount of IBUs that can be dissolved in wort is 100 (beyond that and the iso-alpha acids that create the bitterness are no longer soluble), and you dillute that with water that has 0 IBUs, than naturally the maximum amount you can reach at that point will be 50, which most calculators do not account for.
 
A full boil says 114 IBUs which is impossible. If you want a more accurate depection of your IBUs, and you plan on always adding half the extract at the end of the boil for your partial boil batches, there is a trick on Beer Smith that you can use.

Set the boil volume to allow for a full boil, about 7.5 gallons on mine, and add all the ingredients, including the extract that would normally be added at the end, and see what the IBUs are calculated at. If at or above 100, then you are maxing out, and you can assume about 50 IBUs if topping off with 2.5 gallons, and 60 IBUs if topping off with 2 gallons. If it is below 100, then you can assume about half the number if topping off with 2.5 gallons, and 60% of the number if topping off with 2 gallons. It isn't perfect, but it's close enough without busting out the equations and doing it by hand.
 
BarleyWater said:
A full boil says 114 IBUs which is impossible. If you want a more accurate depection of your IBUs, and you plan on always adding half the extract at the end of the boil for your partial boil batches, there is a trick on Beer Smith that you can use.

Set the boil volume to allow for a full boil, about 7.5 gallons on mine, and add all the ingredients, including the extract that would normally be added at the end, and see what the IBUs are calculated at. If at or above 100, then you are maxing out, and you can assume about 50 IBUs if topping off with 2.5 gallons, and 60 IBUs if topping off with 2 gallons. If it is below 100, then you can assume about half the number if topping off with 2.5 gallons, and 60% of the number if topping off with 2 gallons. It isn't perfect, but it's close enough without busting out the equations and doing it by hand.
Click to expand...

So, just put down 7.5 gallons of water? I'm getting 106 IBU's.

Are you saying I can never get 60+ IBU's if I stick with 3.5 gallons of water boils?

EDIT: I see how it works now, that depending on how much water I top off with will limit my final IBU's.

So, as long as I stick with 3.5 g boils, the highest IBU's I can achieve is around 60, because I'll most likely always be topping off with 2 gallons of water.
 
You know what, judging by your calculations, it seems that it's best to leave off late extract boils on beersmith, because than it calculates 57 IBU's.
 
Feel like I'm the only one who ever brings this point up, but Palmer has also subsequently reported that he was wrong in HTB. Wort gravity has NO direct correlation on hop utilization. This means all the calculators (which more or less relied on his calculations) are also wrong. Unfortunately, exact IBU calculations are not a trivial exercise.

Listen here for Palmer's full report on IBUs.
 
Gravity does impact hop utilization. It doesn't impact the maximum IBUs.

(based on the information I've gleaned from the OSU High AA hop program)
 
You calculated a 50 IBU limit, but this is if you are only boiling 2.5 gallons of the wort and topping it off with the other. What is the IBU limit if you are boiling 3.25 gallons of the wort?

Also, is it true that no matter what method of brewing you do, that 100 IBU's is the limit?

Lastly, is this quote taken from a BYO article correct?

"Although the extract late method allows for hoppier beers than the concentrated boil method, you still end up diluting your wort (and the bitterness it contains) before fermentation. If you want to brew truly bitter, hoppy extract beers, you need to perform a full-wort boil. However, for most stovetop brewers, both the size of their brewpot and the output of their stove preclude vigorously boiling all their wort at once."

So, is he saying I can't get the minimum IBU's to make an I.P.A, even if I do the late extract method boiling 3.25 gallons of wort?

I'm pretty sure you can hit 60 IBUs without having to do a full-wort boil.
 
david_42 said:
Gravity does impact hop utilization. It doesn't impact the maximum IBUs.

(based on the information I've gleaned from the OSU High AA hop program)
Click to expand...

So you've reviewed the data from the 2007 International Brewers Symposium on Hop Flavor and Aroma and disagree with the findings (and Palmer?)
 
emgesp1 said:
So, is he saying I can't get the minimum IBU's to make an I.P.A, even if I do the late extract method boiling 3.25 gallons of wort?
Click to expand...

Basically, yes. The maximum you will ever be able to achieve acieve is 60, if topping off with 2 gallons. I beersmith tells you 106 (or anything over 100), then you must assume 100. You are using 40% water, so you have 60% left. 60% of 100 is 60 IBUs, maxed out for a stove top boil.

If the alpha acids responsible for bittering can't be solubalized beyond the point of about 100 IBUs. Beyond that they reach the point of "saturation", no more will be extracted, because the liquid won't accept it.

EDIT: Reseach has shown that in high gravity beers, a level of up to 120 IBUs may be achievable, but calculation for this are sketchy at best.
 
jkarp said:
So you've reviewed the data from the 2007 International Brewers Symposium on Hop Flavor and Aroma and disagree with the findings (and Palmer?)
Click to expand...

Any links to any of the presentations or data? I'd like to take a look at them, but Google is unhelpful on the topic.
 
I don't beleive Val Peacock's paper has been published yet. david 42 mentioned OSU so I was wondering if he went to the symposium.
 
BarleyWater said:
Basically, yes. The maximum you will ever be able to achieve acieve is 60, if topping off with 2 gallons. I beersmith tells you 106 (or anything over 100), then you must assume 100. You are using 40% water, so you have 60% left. 60% of 100 is 60 IBUs, maxed out for a stove top boil.

If the alpha acids responsible for bittering can't be solubalized beyond the point of about 100 IBUs. Beyond that they reach the point of "saturation", no more will be extracted, because the liquid won't accept it.
Click to expand...

Thanks, this has helped a lot. I have an 8g kettle, will putting it on 2 stove burners be enough to boil 5.5 gallons of water, or will I still need an outdoor propane burner?

FWIW, I own a wort chiller as well.

Lastly, can I do a full boil in my garage, with the garage door opened if I were to use a propane burner? See, it's mighty cold here in Chicago, so I'd like to be somewhat indoors.
 
No problem going in the garage, and the two burner thing may work, depends on your stove really. I would test it with plain water before trying it with your wort, but the burner in the garage, with the door cracked and a fan blowing, is probably the better way to go.

I will say that I just listened to that Basic Brewing podcast with Palmer talking about IBUs, and wow, just wow. I don't even think HE knew everything that was going on at that conference, and they did conclude that wort gravity isn't what they thought it was when getting IBUs. But he did say, that for the most part, the more popular IBU calculations are good within 5 IBUs of the actuall tested IBUs, but those formulas are all jacked up if you listen to that podcast. Some very interesting hop info.

They did conclude that partial boils with extremely high gravities are not good for isomerization, and the dillution factor won't change at all. The only difference, is the max may not be held back by wort gravity, but more the amount of protien and other matter in a boil with that much wort. Basically, they said as far as the homebrewer is concerend, RDWHAHB and keep going as normal.
 
BarleyWater said:
Basically, they said as far as the homebrewer is concerend, RDWHAHB and keep going as normal.
Click to expand...

As in... draw up my recipe in BeerSmith to fit the desired style, use the IBU calculations shown for the full boil (even though mine is a partial) and don't worry about it?

:D
 

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