Giving brewhouse efficiency a closer look

For a while now I have been working on these step by step instructions for troubleshooting brewhouse efficiency. While there are a lot of instructions and suggestions out there on how to improve brewhouse efficiency (one of the most common topics), none of them seem to take a systematic approach to the problem. One of the main ideas behind this system is that the brew house efficiency is the combination of extraction and lauter efficiency which need to be evaluated and fixed independent of each other. Very similar to the idea of limit of attenuation (fermentability) and actual attenuation which are determined by 2 different brewing processes.

In the guidelines I focuses on 3 steps:

- make sure that you measure correctly and calculate the brewhouse efficiency correctly
- determine extraction efficiency and explain how it can be fixed
- show ways to calculate (batch sparging) and test (fly and batch sparging) the lauter efficiency with some suggestions on how to fix it.

I tried to avoid formulas as much as possible and added tables and a spread sheet to make it easier, but if you get the idea behind the calculations it will be easier to follow the steps understand how the tests work.

Glance it over, read it through or even put it to the test. I'm open to feedback of any kind.

Kai

 

Just the Measuring Volumes section has answered questions. My in pot efficiency was always off by about 3 to 5% of actual efficiency and this brings it much closer. This is great so far. I will continue to read on. Thank you for posting this!!!

 

this will most definitely be helpful in the long run for reference and otherwise. Thanks for putting it together!

 

Glad it helped you.

Regarding pre and post boil measurements: Over at the NB forum some brewers reported that the simple formula: pre-boil volume *pre-boil GU = post-boil volume * post-boil GU doesn't work. I checked this for one of my batches and yes some extract seems to be lost in the boil since the post-boil GU is less than expected (in that case by 2 gravity points). The loss of extract was not into the trub (I dried and checked that) and at this point I don't know what is happening.

That may have been another reason for an efficiency difference between pre and post boil numbers.


Kai

 

I believe I read somewhere about the hops themselves absorbing some of the extract and water and this leads to the difference in Pre-Boil Gravity and expected Post-Boil Gravity.

Comments?????

 

But that is not enough to make a difference. I'm missing about 100g from a 5.5 gal batch. The dried trub minus the hops was only 20g. The preboil volume was measured hot and the post boil volume was measured cold. But I corrected for temperature. Next time I'll measure the pre and post boil volume hot.

Kai

 

What do you use as the correction factor of shrinkage between 70F post boil wort and 170F preboil runnings? I know beertoolspro uses some calculation for it but I never looked into the formula. Nevermind, I just saw that you said 3%.

 

I think I remember a discussion about issues with hydrometer accuracy at higher temps, are you using a hydrometer or refractometer to measure preboil gravity? Have you tried cooling a pre-boil sample before checking the gravity?

 

If that's to me, I have cooled it before using the hydro in the last 10 batches or so. Before that I was WAY off

 

The spread sheet is giving me weird readings what am I doing wrong?


grist information value unit
grain 1 amount 23 lb
grain 1 extract potential (leave empty if unknown. 80% will be assumed in this case)

grain 2 amount (leave empty if n/a)
grain 2 extract potential (leave empty if unknown. 80% will be assumed in this case)

grain 3 amount (leave empty if n/a)
grain 3 extract potential (leave empty if unknown. 80% will be assumed in this case)

grain 4 amount (leave empty if n/a)
grain 4 extract potential (leave empty if unknown. 80% will be assumed in this case)

grain 5 amount (leave empty if n/a)
grain 5 extract potential (leave empty if unknown. 80% will be assumed in this case)

grain 6 amount (leave empty if n/a)
grain 6 extract potential (leave empty if unknown. 80% will be assumed in this case)




wort information value unit
total amount of water used to make the collected wort this includes strike and spage water but not water added to comensate for evaporation losses in a decoction. 16 gal


Volume of wort collected 12 gal
Temperature of wort when volume was measured 80 F
Extract or gravity of the collected wort (already temperature corrected) 150 SG

number of run-offs collected 2


optional wort information value unit
first wort extract or gravity
amount of water used to produce the first wort. This includes strike water and water added to the mash before the first wort is run off


Volume in kettle after 1st run off
Temperature of that wort when volume was measured
Volume in kettle after 2nd run off
Temperature of that wort when volume was measured
Volume in kettle after 3rd run off
Temperature of that wort when volume was measured
Volume in kettle after 4th run off
Temperature of that wort when volume was measured




results value unit
brewhouse efficiency (this is efficiency into kettle) 30513158 %
theoretical lauter efficiency 0 %
extraction efficiency calculated from brewhouse efficiency and theoretical lauter efficiency 1052454593103 %

extraction efficiency calculated from first wort extract content n/a %
grain absoption 150683.7345 l/kg
17931.36441 gal/lb

 

Yes, the sample was cooled to 90F and the reading (hydrometer) was temperature corrected. Based on the suggestion of HB forum member I also looked into boil pot expansion, but it is not significant enough and would go into the other direction anyway.

Kai

 

bubbabrewer, Welcome to the board.

The value you entered for SG doesn't make sense. It should be 1.050. 150 would be a gravity units measure but I doubt that you made a 1.150 beer with that grist. 1.050 seems more reasonable.

with 1.050 I get these results:

brewhouse efficiency (this is efficiency into kettle) 72 %
theoretical lauter efficiency 79 %
extraction efficiency calculated from brewhouse efficiency and theoretical lauter efficiency 90 %

extraction efficiency calculated from first wort extract content n/a %
grain absoption 1.83 l/kg 0.22 gal/lb

Which seem reasonable.

Kai

 

Kai,

thanks a lot for that spreadsheet.

1 quick question for you:

my brewhouse efficiency was 61%
theoretical lauter efficiency was 67%
extraction efficiency was 91%

So, my question -- does this mean my mash efficiency isn't as high as it could be? I'm assuming th 91% means I got 91% of the sugars that were available in the mash? Or any I way off base?

okay, that's 3 questions I guess!

 

Yes, your mash efficiency could be higher if you can get the extraction efficiency closer to 100%. This would gain you about 6 points (67% of the 9% that you lost in the extraction step). Check the wort and spent grain for starch.

Was this a particularly large beer (lots of grain) or a no-sparge? 67% seems like a low theoretical batch sparging efficiency.

Kai

 

I think I found an error on my part - volume of wort collected (cell H30) - that should be pre-boil, right? I entered post-boil. If I change it pre-boil, it raises the theo. lauter efficiency to 79% and brewhouse to 72%.

But yes, it was a bigger beer - 12.75 lbs of grain

 

Are there theorectical batch sparg effciency numbers out there? From what I understand it hasn't really been studied, just used by homebrewers. I batch sparge all the time and after worked out some pH issues I had with the mash, I am getting 80%.

 

I have studied batch sparging by using a mathematical model for it. The results are here. In addition to that, the spread sheet does an estimation of the batch sparge efficiency and relies on correct volume measurements to do that.

Kai

 

Hey Kai, I have run into this same exact problem, I am missing 133 grams (+- 9 grams) of sugar in a 5.5 gallon batch. I am trying to understand where its coming from and it doesn't make sense. It dropped my brewhouse efficiency from 85% to 75% and I want to find the culprit. I was hoping that in the past 3 years you might have discovered the source of this missing sugar. I have played around with the idea that the sugars are getting stuck on the sides of the pot, or spoon, or lost in the hops, but unless I am losing a bit to everything it seems like too much to be coming from any of those. Any ideas?

 

I've only got one AG batch under my belt but I figured I should subscribe so I can reference this