General Category > All Grain Brewing
more efficiency questions...
goschman:
Hi All. So I brewed an all munich pale ale yesterday and overshot my average efficiency by about 10 points and got my highest efficiency ever. I have a feeling it may be due getting my grain from a different shop. Their mills seem to be set to a smaller gap width since it took a lot longer to mill the grain. This aside, I have some process questions and how much they contribute to efficiency.
My mash water and sparge water volumes were almost identical. I have heard that this can increase efficiency. Any truth to this?
I batch sparge. When adding 180F sparge water the mash stabalized at 168. I try to hit 168-170 regularly but sometimes am not successful.
Any feedback would be much appreciated as I am going a bit crazy. My last batch was at about 66% efficiency while yesterday's was about 79%. It has become hard for me to predict my OGs which is really throwing a wrench in recipe design.
Kaiser:
goshman, your changing efficiency is likely caused by changed in the conversion efficiency during mashing. This efficiency is affected by mash parameters like crush, mash pH, mash thickness, time and temperature. The further you are away from 100% the more changes in these parameters can affect it and your overall efficiency. Here is some detailed reading on the subject:
http://braukaiser.com/wiki/index.php?title=Understanding_Efficiency
don't be put off by the formulae in this article. You don't have to understand them fully to understand the underlying concepts.
Kai
a10t2:
Kai nailed down all the variables. Were the grists similar? Did you check mash pH? Crush is definitely a big factor, but I'd think the original crush would have to be truly awful in order for it to be possible to get a 20% boost in efficiency. Kai's experiments showed a maximum variation of ~10%.
goschman:
Thanks for the link...I will go through it when I have some time.
I do not measure mash pH. I think this is the one factor other than crush that may be affecting my results. Shouldn't my mash pH be somewhat consistent when using the same water and mash thickness? May be a stupid question and I assume the answer is no.
I try to keep my mash thickness consistent at about 1.4 qts/lb.
Last batch I did a 90 minute mash at 150
50% Two row, 43.5% white wheat, 6.5% midnight wheat - 65.9% efficiency
This batch I did a 60 minute mash at 154
100% weyermann munich I - 79.2% efficiency
The grist was nowhere similar but I usually get 66-70% efficiency regardless of the grist. I guess I will have to keep plugging away at my process and learn as much as I can.
Kaiser:
Mash pH depends on water (+salts+acids), mash thickness and the grist. For your two grist examples the 2nd grist likely leads to a lower mash pH than the first grist. Most likely that also means that it was closer to an “optimal” mash pH.
To troubleshoot your efficiency issues I strongly recommend that you start doing the mash gravity test. The idea of the test is to measure the wort gravity of we well mixed mash and compare it to the max that would be expected based on the mash thickness. you can use this table:
Brewer’s Friend also implemented this as one of the log entries you can create.
Kai
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