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New IBU formula in BS 2.0?

Grumpyowl

Grumpyowl

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Hello,
When importing my recipes from version 1.4 into 2.0, it appears that my original IBU changed a bit.
Does the new version feature different formula than version 1.4?  I use Rager formula for both version.
Thanks for any insights!
Olivier
 
Hi,
  There was a slight adjustment to account for losses to trub/chiller which were not included in the earlier version.  Technically these are part of the overall batch volume for the "post boil" volume, so the net effect is a slight lowering of IBUs.  Separately we added a slight plus up for pellet hops - so overall the change should be small.

Brad
 
So are you saying the formula in 1.4 was incorrect?

Here's my example:
5.5 gallon batch size, 1.055 pre boil SG

v1.4 has .75oz of 14% at 60 minute is coming in at 31.3 IBU Tinseth

http://www.realbeer.com/hops/bcalc_js.html (Tinseth's javascript calculator)
has it coming in at 32 IBU (So we're good so far)

v 2.0 has it coming in a 35.1 IBU Tinseth

Now, that doesn't seem like a big difference, but that actual hop total between 1.4 vs 2.0 differs by 9.3 IBU.  I'm not entirely sure if that REALLY matters in the grand scheme of things, but writing an AIPA recipe and I'm coming in at 76 IBU, I'm inclined to leave it be even with it being a few IBU over "official" style, but just eyeballing 85 IBU made me think about tuning it down a little.

If you're calling it the Tinseth scale, why does it differ from his numbers?

I'm assuming this is just going to be a mental adjustment that I'm going to have to make based on what I like my beers to taste like, but I think It might throw me off when doing styles I'm not completely comfortable with just yet.

 
All IBU calculations become less and less reliable the more hopes are added.  BeerSmith is trying to account for more of the entire brewing session rather than a calculation based on gravity and volume + hop amounts. While bitterness really matters to the overall drinkability of the beer, ALL calculations are inaccurate.  Every brewer has to adjust the bitterness to their own scale based on their system.  Your equipment, process and water all make a profound difference. 

Pick one formula like the one developed by Glenn Tinseth and stick with it.  You need to determine what 75 IBUs are on YOUR system. It takes a few brews and best doen on the same recipe but in three or four you should be able to determine what a 75 means to your beers and adjust hops up and down accordingly.  On my system I usually knock 10 IBU points of the bigger beers.

Also, the age of hops is really important.  Last years crop is already 30-50% of the alpha acids on the package.
 
Well, let's assume that they're the same age.  I imported everything from 1.4 without changing a single setting.

I understand the concept of knowing what 75 IBU means to me.  I remember hearing Jamil or Palmer say that on a Brewstong a while ago, which leads me to my next question...

What I'm trying to figure out is, should what I knew as 75 IBU (or whatever) from Beersmith 1.4, now really be 85 IBU?  I straight upgraded from what I had.  Running the programs side by side gives different results, with 1.4 being closer (within less than an IBU) to what Glenn Tinseth says his Tinseth IBU formula should be.  Is there something different I need to set in BS 2.0?  If there isn't, to me, BS 2.0 is wrong if it's calling it Tinseth when Brad's formula in 1.4 is near identical to what Glenn says. 
 
Your question is quite valid.  Based on what Brad already said, I would not have expected it to change like that.  What happens if you recreate the recipe in 2.0?

 
I'll try a new recipe from scratch in a few, but I did a side by side comparison of my last 15 recipes and their IBU counts.  In every single case, my 1.4 recipes were between 90-91% of the IBUs in the 2.0 recipes.  Brad, is this just the increase you're talking about that you gave to pellet hops?
 
Ok after I stopped being lazy and looked through the options, I noticed that in 1.4's Hop Utilization is setup inverse to what 2.0's does.

1.4 gives options for Leaf and plug adjustment, set to -10% and -8% respectively

2.0 seems to handle it the opposite way, with Leaf being set to 0% adjustment, Plug to +2% and Pellet set to +10%.  Which makes sense to why my IBU calcs were roughly 9% different.

So, if I was so inclined I can just turn off that adjustment, since it's the Brewhaus comfort factor of knowing my system and setup.

Ok, I feel better now that I did some looking.  Thanks for the replies.
 
BeerSmith said:
Hi,
  There was a slight adjustment to account for losses to trub/chiller which were not included in the earlier version.  Technically these are part of the overall batch volume for the "post boil" volume, so the net effect is a slight lowering of IBUs.  Separately we added a slight plus up for pellet hops - so overall the change should be small.

Brad
Click to expand...

Shouldn't that then also be true of the OG calculation?

Chris
 
janzik said:
Ok after I stopped being lazy and looked through the options, I noticed that in 1.4's Hop Utilization is setup inverse to what 2.0's does.

1.4 gives options for Leaf and plug adjustment, set to -10% and -8% respectively

2.0 seems to handle it the opposite way, with Leaf being set to 0% adjustment, Plug to +2% and Pellet set to +10%.  Which makes sense to why my IBU calcs were roughly 9% different.
Click to expand...

Someone here pointed out that Tinseth's model was based on whole leaf, so the base formula in v1.4 was applying the whole leaf factor incorrectly.  Brad fixed that by using pellet adjustments instead.  If you use whole leaf hops, and zero out the adjustments, you should get close to Tinseth numbers.  I think Brad's formulas use some additional tweaks based on factors that Tinseth ignored, so it may not be exactly the same. 

 
ChrisNH said:
Shouldn't that then also be true of the OG calculation?
Click to expand...
That's correct Chris. The OG, bitterness and colour all derive from end of boil and will read correctly as long as your 'Brewhouse Efficiency' or 'Tot Efficiency' and 'Loss to Trub and Chiller' are set correctly. One thing that can be hard to get used to is that any time you change your 'Loss to Trub and Chiller' figure, you must remember to also adjust your 'Brewhouse Efficiency' figure accordingly.

There's a spreadsheet in this post to help you do this. (Thread also contains a link to an online tool).

Cheers,
Pat
 
Pat,

I have gone back over my original notes.. I need review again how I produced the issue since what I just described does not quite work. My issue is somewhat more subtle.


I think that all I need is to have the starter size take trub loss into account.

Chris

PS - I fired up brewsmith at lunch. I have verified, at least in build 40, that changing trub has no impact on OG. What was happening was I was trying to get the volumes correct through the process and out into kegging.

So.. in order to represent the 5.5 gallons into the fermenter I was setting batch size to 5.5, setting brewhouse effeciency to compensate for that change.. then putting in 0.5 gallon trub loss to get the correct volumes in my boil. Then, of course, the 0.5 gallon loss before I go to keg.

Its created a problem for me chasing the amount I need in the boil, the amount for the batch size for recipe purposes, and the amount that actually goes through the processing for fermenter and keg.

My desired view is this:

Boiler Column ---> Batch Size ----> Trub Loss---> Fermenter Volume---> Fermenter Loss---> Bottling volume

Which will decouple the the trub loss from the boil volume and the batch size from the starter volume. It would allow my recipe to be a "6 gallon recipe" which is more correct were I to be copying it off for a friend or publishing it in a book.


Chris
 
Thanks Chris for the above. (Wandered off track last night so I got rid of my irrelevant posts ;))

I think Brad is thinking on how to give the user an option to work off either 'Mash Efficiency' or 'Brewhouse Efficiency'. I'd love this as I spend a lot of time converting recipes and find 'end of boil' the easiest common ground to work from. (Most recipes on the net are really hard to convert to your equipment as the provider rarely gives enough information or uses ambiguous terminology such as 'Batch Size' and 'Efficiency' which are terms that mean different things to different brewers unfortunately.)

If he is able to do this, I think this would make things much easier. While the calcs are correct in BeerSmith2, it is quite easy to make an error. eg Change 'Loss to Trub and Chiller' and then forget to adjust your 'Brewhouse Efficiency' accordingly and your OGs etc will be incorrect. I still sometimes forget :D. And it is difficult to work out how much to adjust it by. Setting 'Loss to Trub and Chiller' to zero and then making 'Batch Size' your end of boil volume is what many people, like you and me, currently find simpler.

If you were able to 'lock in' your 'Mash Efficiency' in BeerSmith, I think that would solve all your worries. Do you reckon it would? (I couldn't quite follow some of your figures above but I think I got the general idea ;))

Cheers,
Pat

P.S. On the sharing of recipes, use either the 'Classic Recipe' report or the 'Plain Text' one as they include, 'End of Boil Volume,' 'Batch Size (fermenter)', 'Brewhouse Efficiency' and 'Mash Efficiency' which makes interpretation much easier.






 
Completely selfishly, the way it would work if I had it exactly my way would be that trub loss would have no impact on boil volume. Instead, it would only modify an "estimated fermenter volume" which would be used for starter.

Using my current method, brewing a 6 gallon recipe as a 5.5 gallon batch, I just multiply my mash efficiency by 5.5/6 or about 0.92

Currently I am using 74% for mash. That means I get 68% effective. I am moving to a new mash tun with my next batch and will probably have to rework that.

I am not sure I answered to your comments.. but thats where I am.

An alternative "solution" would be to just have the ability to set a fermenter volume in the starter rather then use the calculated volume but I think that would just be kicking the can.

Chris

 
Sorry Chris, my head keeps spinning any time I read 'Starter'.

I have been trying to work out what you mean for three days on and off at least - lol!

I'm half getting what you are saying but the starter thing keeps throwing me. If your 'starter' question relates to the 'Yeast Starter' tab then don't worry about replying as I haven't even explored that one yet  :D

Cheers,
Pat
 
Yes, it relates to the yeast starter tab. Currently, batch size sets the target yeast count. Because of that, batch size needs to reflect what is in the fermenter when the yeast is pitched for that tool to work correctly.

Chris
 
Chris,
  I believe if you mouse over the batch size you will see that it is defined as the amount of wort going into the fermenter - so it is correct to use this number for yeast counts.

Brad
 
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