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Beersmith Hop ulilisation calculation and boil volume

B

BeerMonster

Im having trouble making sense of the IBUs calculated by Beersmith for a given boil volume versus recipes from outside of beersmith.

Im making Port O’ Palmer Porter from page 136 of How to Brew 3rd edition, using the extract method plus steeping grain (as per the recipe).

It calls for :

14g Horizon 12% 60 mins 21 IBU
21g Willamette 5% 40 mins 12 IBU
14g Willamette 5% 20 mins 5 IBU.

Total IBU 38.

Putting this into Beersmith with a batch size of 19L and a boil volume of 19L gives 38 IBU. All is well.

But I only have a 10L stockpot. So I change the boil volume to 9L. Beersmith recalculates the IBU to be 21.

I initially think this is realistic as there will be poorer hop utilization with less boil volume. Im just about to up the hop weights by around 100% to get BeerSmith to calculate the final IBU to be 38.

But then I notice the recipe uses a boil volume of 11.4Litres and not 19L. This implies the recipe would give 21 IBU (or thereabouts) despite the book saying it is 38IBU.

So how can Beersmith calculate an IBU of 21 with a boil volume of 9L, yet the recipe calculates 38IBU with a boil volume of 11.4L and gets 38IBU ? Clearly I have entered the initial data correctly since Beersmith agrees with the recipe for the hop quantities used when the boil volume is the same as the batch volume.

One of them has to be wrong, or else Im missing something. 38IBU versus 21IBU is significant in my opinion. Although clearly Im just learning and haven’t really used Beersmith in anger yet – so there’s plenty of scope for a decent explanation and education here.

Colin
 
That all sounds very odd. Typically with a smaller wort volume you should get better utilization, as you would normally have a more vigorous boil. I don't see how decreasing the boil volume would decrease the IBU's. For all intents and purposes it should increase the IBU's, as you will have a higher mg alpha acid/liter ratio.

Putting that recipe into beersmith, I get 38 IBU's with a 19L batch size. When I drop it down to a 9L batch size, I get 49 IBU's. Not sure what's going on there.

Darin

 
Well I dont understand that ! I havent, that I know, altered anything to do with hop calculations in Beersmith. But something is different between your setup and mine then.

Would you try uploading my recipe (attached) and see if its the same ? Ignore everything but the ingredients, that's just a cut and paste from a random recipe. As it is it gives 37.5IBU with a 20L boil and 21.2IBU with 9L boil. Well, it does for me anyway !
 

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  • porter.bsm
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There must be something in your setup that is causing this. I opened your recipe and played with the volumes, and I get an increase in IBU when Decreasing the volume also. I will play with it to see if I can find the issue.

Cheers
Preston
 
OK, thankyou very much. At least that narrows it down somewhat.

Im no expert brewer, far from it. But I thought a higher gravity gave lower hop utilisation ?  In layman's terms, less water to suck out the hop flavour ! And to my tiny mind boiling in 20L of water instead of 9L should give a lower gravity boil, ie much more diluted, less dense, less gravity etc etc. and therefore HIGHER hop utilisation at the higher boil volume since there's more (clean) water with which to extract the hop goodies ? So I hadnt thought anything strange about my setup until I started questing it against the recipe - and now others' setups.

Also as far as I know, everything is set to defaults in beersmith excepting I added my own equipment to reflect the 10L pot.

Anyway - the point of this post - here's the exact same recipe with a boil volume of 9L giving an IBU of 21.2 in my setup. Just in case it helps locate the issue.
 

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  • porter 9l.bsm
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Is there a typo somewhere in the initial post?  Your equipment setup has the mash-tun volume at 2.64 gallons, or about 10L.  If your only pot is 10L, then you cannot physically have a boil volume of 19L, right?  Even with a 19L pot, your boil volume will be less than the pot's maximum. 

The batch size can be 5 gallons due to the added top-off water poured in the fermentor (post boil), but your boil volume in a 10L pot might be something like 7L?  At least until the hot break is safely over, then you could add some water back to maximize the boiled amount, which may help hops utilization a little. 

Lots of brewers do 5 gallon batches in 19L pots, adding about 2 gallons of clean water post-boil.  So do you typically add about 3.5 gallons of water post-boil?  If so, that's a very concentrated boil, and I could see BeerSmith having trouble with the math unless your get your equipment setup figures exactly down. 

Hope that helps.  Re-post if I read that entirely wrong.
 
The amount of water in your wort really has nothing to do with utilization. Hops are not very soluble in water, and it takes a lot of heat for isomerization to occur. The presence of sugars and lipids makes it more difficult to isomerize the alpha acids, so therefore a higher gravity wort will result in lower utilization. You were right about the gravity, but not the reason for the lower utilization with higher gravity. Conversely, while researching this topic I learned that the presence of Magnesium ions acts as a catalyst for isomerization. So therefore, you can attain a higher utilization % with higher Mg++ levels. Though you don't want to excedd 65 ppm, as it can become harmful to yeast in those concentrations. I have not tested this, and have not seen any empirical data to back it up; but I did find it from several different sources.

Darin
 
MaltLicker said:
If your only pot is 10L, then you cannot physically have a boil volume of 19L, right?  Even with a 19L pot, your boil volume will be less than the pot's maximum. 

Hope that helps.  Re-post if I read that entirely wrong.

Yes you're right - my pot is 10L, so the boil would be 9 or even less. I havent got down to accurately putting the data in, since I cant make sense of it when I make large adjustments.

So yes, my pot cannot have a 19L boil. But if I change my pot to, say, a 30L one then the same observations are true regarding the IBUs - namely they are 38 for a 9L boil and 21 for a 19L boil, yet the Dave Palmer recipe says 38IBU for a 11L boil.

So your point is quite valid - but consider my post re-posted with a 30 or 40 L pot (or whatever) that can contain a 20L boil ..... my observations remain (not that they're correct, there's obviously something amiss !)

 
BeerMonster said:
Yes you're right - my pot is 10L, so the boil would be 9 or even less. I havent got down to accurately putting the data in, since I cant make sense of it when I make large adjustments.

Since your pot is half the size of Palmer's, I'd start with entering your exact size and water capacities.  Those measurements are "fixed" in the short-term.  There are lots of dependent calculations that happen inside BeerSmith, so it's usually best to verify and enter the known factors first. 
 
Well that in essence is my problem.

I start with a known recipe (ie Porter's as per my first post) and a known IBU of 38 according to Porter. 

Entering it into Beersmith I get the predicted IBUs to be 38  if, and only if, I use a boil volume of 20L.

But Porter's recipe uses a boil volume of 11.4L.

According to Porter's recipe (using the hops in my first post) that would give an IBU of 38 for a boil volume of 11.4L.

According to Beersmith (using the same hop list) it would give an IBU of 21.

My point is, one of them is wrong. Given Ive made Porter's recipe and it's indeed very nice, Im thinking something is wrong with my Beersmith setup since 21 IBUs is unlikely to give a nice tasting porter (or anything some to that).

Dunno if Im making my point too well here. Im just saying surely a recipe from the famous "How to Brew" should match at least approximately the IBUs predicted by Beersmith for the same boil volume ?

 
Wrong might be a subjective term here.  I am no expert here but I believe there is more than one way to calculate hop utilization (e.g. Rager vs. Garetz).  I know I've heard Jamil (who I would bet uses the same method as Palmer) actually name the method he uses to calculate hop utilization. I'm not sure which method BS uses to calculate this but the answer may be as simple as Palmer and BS calculating hop utilization differently.  

addendum:  Well, I got curious so I entered the recipe into BS just as Palmer has it.  I entered it as an All grain batch assumed a 75% efficiency as Palmer does and a batch volume of 5 gallons, again as Palmer does.  

The IBUs BS calculates is 38.8 which is obviously very close to the 38 listed in the book.  So, I would suggest making sure the grain bill is the same, believe it or not this can make a difference and that the hop AA's you are entering aren't different from what Palmer lists (BS and Palmer don't agree on the AA's for all the hops).  I'd also make sure you've accounted for your efficiency (assuming you are making an all grain batch).  If your efficiency is lower and you don't adjust for this, your hop utilization will be greater.  

Try entering everything in just as Palmer has it and make sure the assumptions are the same and see what that tells you.  If you're not close then I'm not sure what to tell you?  If you are, then start changing the variables one at a time to more closely match your system.  See what changing each variable does to that IBU number.  That way, I'm guess you'll be able to narrow down what it causing the issue.

Addendum Addendum:  I looked at your Porter recipe and you don't have the right hops or AA in there.  You have cluster and an AA at 5.5 and not Horizon which should have an AA around 12. Also, the AA levels of your Willamette are low compared to Palmer who has his at 5.  Change these and my guess is your problem will be solved
 
Wildrover - thanks for your time looking at this. Maybe Ill get to the bottom of it !

Most important first :

Well, I got curious so I entered the recipe into BS just as Palmer has it.  I entered it as an All grain batch assumed a 75% efficiency as Palmer does and a batch volume of 5 gallons, again as Palmer does.  

The IBUs BS calculates is 38.8 which is obviously very close to the 38 listed in the book.  

But what boil volume did you use when you did this ? If you used 18.9L / 5 gallons then your Beersmith would roughly agree with mine with an IBU of around 38 IBU. Im guessing this is what you did.

But this wouldnt in fact be in agreement with Palmer because he uses a boil volume of 3 gallons or 11.4L. To quote his text (p136 or here http://www.howtobrew.com/section2/chapter13-3.html where he isnt quite as explicit but note he simply brings his 3 gal wort to the boil - no water added ie boil volume 3 gal or thereabouts) :

Add water to bring the wort volume up to 3 gallons (11.4L). Bring to the boil. Add hops as per recipe.

Assuming this is what you did (ie used a batch of 5 gal, and a boil 5 gal) what happens if you change the boil volume to 11.4L (or 3 gallons) as per Palmer ?

If your Beersmith is like mine that will give you an IBU of around 22, which is miles away from Palmer's prediction.

PS :

Wildrover said:
Addendum Addendum:  I looked at your Porter recipe and you don't have the right hops or AA in there.  

yes, you're right, I posted the recipe substituted with the hops I can get hold of, but adjusted the weights for the same IBUs but using the diffferent AAs. If I use the exact same hops as Palmer it gives a very similar result of 37IBU for a 18.9L batch but again only using a 18.9L boil. Using the actual boil volume of 11.4L still gives 22IBU or thereabouts - ie still an almost identical and very significantly different IBU prediction than that of Palmer's recipe.

When you say am I doing an all grain - well Im doing it as per Palmer using 3Kg of palm malt extract, so in fact no, Ive entered it as an extract recipe.
 
BeerMonster,

I assumed this was an all grain batch since this is the AG board and I was looking at the recipe on pg 223-224 where they list the all grain option, not pg 136 where he just has the partial mash version.

Anyway, I can get mine to work out just fine using a boil volume of 3 gallons.  I opened your attached recipe again and worked with that.  The things that i might suggest are:

Check your efficiency, even with a partial mash, this still has an influence.  Palmer assumers 75% so make sure your brewhouse efficiency is set to 75%.

Also, the AA in the hops you have listed are not the same.  Again, if you delete your cluster which is listed at 5.7 and add horizon which is at 12% this will make a huge difference in an of itself. 

Also, raise the AA on the Willamette to 5% from the 4.8 that you have listed and those few things should bring you up to 40.3. 

In summary, I have my BS set to 75% efficiency.  A five gallon batch with three gallons boil volume.  I also changed the hops to match Palmer's as well (and this I think is most important) made sure the alpha % also matched what he listed. 

This should fix it for you.

Of course, when you make the recipe its more important that you are entering the hops you have and using their alpha percentages but for now, to get your problem worked out, try to make those quick changes and see if that doesn't fix it for you.   
 
Wildrover,

thankyou again for your time here.

Well I posted here under the "advanced" topic rather than all grain ... in fact Im about to do my first all grain when I can be confident I have mastered Beersmith sufficiently !

OK, attached is the Palmer's porter recipe as per p136, all ingredients correct according to me that is.

Ive also attached two screenshots of the recipe in Beersmith. One shows 37 IBU (near enough what we expect) for BV 18.9L. The second shows IBU 27 for BV 11.4L. Both have efficiency of the default 75%. So Im still wrong at 27 IBU, but I dont know why !

Interestingly the 11.4L boil isnt 22 any longer, but 27. Still not the same as Porter, nowhere near, however for reasons I absolutely do not understand the final IBU has changed with the use of a different alpha and weight all be it for the same individual IBU for that hop addition. So this is as you said it would be ... but Im still not right at 27 IBU and a 11.4L boil ?

So with the attached recipe, what IBU's do you get for the two Boil Volumes of 18.9 and 11.4 L ?


 

Attachments

  • Palmers Porter 37 IBU.bsm
    13.2 KB · Views: 277
Try updating Beersmith. I see you have an older version installed. This may fix your issue.

Hope this helps

Cheers
Preston
 
BeerMonster,

I've taken another look at your recipes and after thinking about it for a bit my best conclusion is that you and BeerSmith are both right but Palmer is too but there is some inconsistency between everyone that I'll get to in a second.  

Remember all the recipes that are generally given for extract batches usually have an all grain option that almost always tells us to reduce the amount of hops if doing an all grain batch to account for greater hop utilization.  

It makes sense to me that when I enter the all grain batch into BeerSmith and I get close to 38.8 IBU's with my full wort boil that I should not get that if I reduce my boil volume by half (and I don't when putting all this into beer smith).  

Having said all that on page 213 where Palmer is talking about his assumptions for the recipes, if you look at the bottom of the page where he discusses hop schedules he says "The hop utilization factor is a function of the boil gravity.  I have attempted to keep the hop schedules the same across each version of a recipe by manipulating the quantity and form of malt extract (dry/liquid), so that the gravity of the boil is the same (within a couple of points) whether you are using the 3-gallon boil (extract-based) or the 6 gallon boil (all grain).  I wanted to avoid confusion over the hop quantities for each recipe.  However, you may want to verify the gravity of your boil, depending on the specific size of your pot and recalculate the hop utilization factor accordingly"

Keeping this in mind, its important to remember that the higher the boil gravity the less hop utilization (and vice versa).  Palmer does address this by saying he adds only a portion of the extract at the beginning of the boil to keep the boil gravity close to what the boil gravity would be for an all grain batch and then adds the rest at the end of the boil when hop utilization has already been established.  

In other words, extract and partial mash with extract shoot the gravity of what is being boiled through the roof.  Extract brewers bring the gravity back down when they add the top off water what at the end.  All grain brewers do the opposite.  The gravity of what they are boiling is lower than what they will end up with but over the course of the boil they boil down which shoots the gravity up.  So in a way the extract (partial boil) and all grain (full wort boil) start at opposite ends of the gravity spectrum but through boiling down or topping off they sort of meet in the middle.  All great, right?  But since hop utilization is a function of the boil gravity (higher gravity = less utilization, partial boils = greater concentration = higher gravity = less utilization)  adjustments need to be made in order to achieve the same effect.

Palmer does this simply by putting less extract in during the boil and then the rest at the end to keep the boil gravity close to that of an all grain batch.  

You need to mess with the volumes of extract you put in for the entire boil to figure out how much you can put in to achieve the same hop utilization.  After you have all that figured out you can simply add the rest of the extract at the end of the boil.  Messing around in BeerSmith for a three gallon boil all you need to do is cut the extract in half (only put in 3.3 lbs of extract for the entire boil and add the other 3.3 at the very end, this is consistent with what Palmer says about his recipes and works out in beersmith to 38.8 IBUs)

Hope this helps

p.s.  if this is confusing read chapter five of the book, he goes into better detail and probably explains it a lot better but the moral of the story is you are all correct!
 
Wildrover, you are exactly right. After reading through all the postings I came to the same conclusion. With the higher gravity the utilization will drop dramatically. With wort gravity of 11.1 Plato (This is for the full boil gravity) your utilization at 60 minutes is 24%. With wort gravity of 19 Plato (the 11.4l boil volume gravity) it's 17%. Big difference.

Darin
 
Wildrover,

I can only conclude that brewing beer is good for your intellectual capacity. I keep telling my wife I need more gear to try all grain etc, now I know why !

That explanation makes perfect sense, thankyou. I had become transfixed with technology and overlooked the seemingly (to me) trivial or 'fine detail'  fact that Porter adds his second extract after the hop boil. Bad mistake. I had even read the chapter you refer to, but of course it's all new and not everythng sinks in first time.

So as you point out, and as verified completely in Beersmith like you suggest it will be, doing so is very significant indeed. If I take out the second can of extract, I dont think Beersmith will let me add it later for an extract recipe, I get 40 IBUs with an 11.4L boil ! Spot on, thankyou very much for explaining that.

I think what might have thrown me initially is it seemed others could apparently reduce their boil volume without the IBUs coming down significantly. This can only have been because they weren't using the full recipe, or the recipe exactly as I had it enetered for an extract brew, right ?

 
Playing around some more now I understand a little better, I find several of my previous extract recipes show the same problem - ie way too low IBU predictions. However these (mainly from 'Brewing beers like those you buy' and the like) are primarily extract recipes with options for all mini-mash and grain. But they are so specific ie step by step, there is no option or suggestion to delay the addition of extract to adjust the boil gravity.

However, plying with these recipes in Beersmith I discovered that the selection of the Bittering method (Tinseth/Rager/Garetz) has a major bearing on the predicted IBUs. So for example taking a recipe for Landlord's Strong Pale Ale, and using the spciefied boil volumes of 9.5L in this case, Beersmith predicts the final IBUs to be 34.5 against the recipe's 33IBU if Rager is the bitterness method. Close enough !

But if Tinseth is used, predicted IBUs are only 24.6. Garetz gives only 19.9.

So it seems to be equally as important to select the appropriate Bittering method (for the recipe being used - maybe extract requires a particular method ?). This implies an understanding of the various methods, which to date I do not have.


 
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