Sudden strange efficiency issue

[beervoid]

Hello everyone.

I've been brewing on a grainfather type machine for about 2 years. Efficiency has been all over the place and just when I thought I had it down I run into this low efficiency again.

I currently have 2 similar machines and did 2 batches on the same day.
I usually mash for around 90 mins but after a bit of reading wanted to test out the theory that full conversion happens in the first 30-45minutes.
So instead of mashing for 90min + mashout, I did a 60min + mashout.

I usually get around 72% efficiency but now on both batches I got around 62% Both batches had similar grain bills. Mostly pale malt with a bit of oats 8% and malted wheat 5%.
One hit 1.055 instead of 1.065 and the other hit 1.64 instead of 1.075. Oddly similar loss of around 10 points on both.

Difference with my usual batches?
8% rolled oats (use malted or flaked wheat usually)
Mash time 60min instead of 90

Now here come the strange (for me) thing.
Since I've been having recirculation issues I have widened the gap size on my mill slowly from 0.038" to find a sweet spot.
Batch 1 was milled at 0.042" and batch 2 at 0.050".
I'm surprised both batches had roughly similar low efficiency even when the the gap size was pretty different.
This leads me conclude my low efficiency is not a milling size problem. Recirculation was better on both batches, but still pretty slow.

I've used rolled oats before even at higher % but cant recall taking a big efficiency hit from them.
I wonder if its the shorter mash that is to blame which goes against what most literature suggests should be enough for full conversion.

Any suggestions, idea's so understand this issue would be greatly appreciated.

Cheers

 

[doug293cz]

Time to convert depends heavily on grit size (larger mill gap => larger grits.) The rate controlling step in conversion is gelatinization of the starch, which proceeds from the surface inwards. The larger the grits, the longer it takes to gelatinize all the way to the center of the grit. The data on converting in 30 minutes or less is for very fine crushes.

Brew on

 

[brewbama]

*I do not brew on a Grainfather*

I have tracked my mash every 20 min for the last several batches. I used the same grist bill, set up my pump flow, grain crush, and brewing liquor the same for each of these batches. Each batch followed a very predictable pattern + or - 2%: 20 min - 75% SG, 40 min 85%, 60 min 92%, 80 min 97%, 90 min 100% SG. I went to 100 and 120 at first but found no increase so stopped at 90 min. Every time, it took 90 min until I stopped recording an increase.

I say all that to say this: I mash until I no longer measure an increase in SG. Not a set time. The 60 min mash is an “all things being equal” compromise. No system is the same given all the variables.

Your system setup may require 100 min, or 120, or 60. But measure so you’ll know. My system produces very predictable results every time. Find your system’s setup and you’ll never be more pleased in the results.

 

[JaymzMF]

Do you stir the mash every so often? I found that helped my efficiency quite a bit. Something I didn't know I should do until recently. Helps to keep a uniform heat, even with re circulation.
Is your temp accurate?

I thought those all in one systems pull easy 80%?

 

[Jag75]

Are you using the Gf app for recipes and using the water calculations from it? If yes then your crush is the reason . I use the Gf and I'm consistently in the 80s. Use rice hulls when using oats and wheat instead of milling wider .

 

[day_trippr]

I realize the knurling patterns on mills differ thus one person's .030" could be another's .025" or .035"...but .042" or .050" is going to be efficiency-challenging pretty much regardless of mill design. One would need to add a lot of gelatinization time in an attempt to make up for the crush and would still likely suffer reduced efficiency...

Cheers!

 

[FatDragon]

"I thought I had solved my efficiency problems, but then I changed two of the most crucial variables and suddenly my efficiency dropped again!"

User error. To achieve consistent results, apply a consistent process.

 

[beervoid]

"I thought I had solved my efficiency problems, but then I changed two of the most crucial variables and suddenly my efficiency dropped again!"

User error. To achieve consistent results, apply a consistent process.

Which variables?

 

[beervoid]

I realize the knurling patterns on mills differ thus one person's .030" could be another's .025" or .035"...but .042" or .050" is going to be efficiency-challenging pretty much regardless of mill design. One would need to add a lot of gelatinization time in an attempt to make up for the crush and would still likely suffer reduced efficiency...

Cheers!

Time to convert depends heavily on grit size (larger mill gap => larger grits.) The rate controlling step in conversion is gelatinization of the starch, which proceeds from the surface inwards. The larger the grits, the longer it takes to gelatinize all the way to the center of the grit. The data on converting in 30 minutes or less is for very fine crushes.

Brew on

Following that logic I would expect the finer crushed one to have a better efficiency.
But I get your point.

 

[beervoid]

*I do not brew on a Grainfather*

I have tracked my mash every 20 min for the last several batches. I used the same grist bill, set up my pump flow, grain crush, and brewing liquor the same for each of these batches. Each batch followed a very predictable pattern + or - 2%: 20 min - 75% SG, 40 min 85%, 60 min 92%, 80 min 97%, 90 min 100% SG. I went to 100 and 120 at first but found no increase so stopped at 90 min. Every time, it took 90 min until I stopped recording an increase.

I say all that to say this: I mash until I no longer measure an increase in SG. Not a set time. The 60 min mash is an “all things being equal” compromise. No system is the same given all the variables.

Your system setup may require 100 min, or 120, or 60. But measure so you’ll know. My system produces very predictable results every time. Find your system’s setup and you’ll never be more pleased in the results.

Thanks for this. Im inclined to believe it is the mash time.

 

[beervoid]

Do you stir the mash every so often? I found that helped my efficiency quite a bit. Something I didn't know I should do until recently. Helps to keep a uniform heat, even with re circulation.
Is your temp accurate?

I thought those all in one systems pull easy 80%?

I tried many different things. Till I got a persistant 72% efficiency.

 

[beervoid]

Are you using the Gf app for recipes and using the water calculations from it? If yes then your crush is the reason . I use the Gf and I'm consistently in the 80s. Use rice hulls when using oats and wheat instead of milling wider .

No I use my own made beersmith profile that gave me persistent efficiency for many brews untill these ones.
I use rice hulls as well. If its the crush why did I get less efficiency on both systems with different crush size?

 

[beervoid]

I realize the knurling patterns on mills differ thus one person's .030" could be another's .025" or .035"...but .042" or .050" is going to be efficiency-challenging pretty much regardless of mill design. One would need to add a lot of gelatinization time in an attempt to make up for the crush and would still likely suffer reduced efficiency...

Cheers!

Im starting too think that as well as the settings reccommended by different people found on the internet differ by alot.

The wider one of the two still had a pretty good crush. I use a feeler gauge to meassure the gap exactly. The one with 0.042 still produced quiet some flower and recirculation was not as good as the other.
Im thinking my crush can still go up as even the 0.050 crush still had quit a bit of flower as well.

 

[day_trippr]

How fast are you running your mill? High speeds tend to produce fines even with larger roller gaps.

Have you tried conditioning the grain just before crushing? At least with roller mills (I don't know if it works with disc mills) it allows a tighter crush while preserving husk integrity - which in turns helps with lautering...

Cheers!

 

[FatDragon]

Which variables?

You coarsened your crush (and inexplicably used two different crush gaps on the two batches) and shortened your mash length on the same brew day. Both of those are liable to reduce your efficiency. If you had finally achieved consistency with your process, why would you make changes to it? And for that matter, why make changes that are likely to hurt your efficiency? I understand a shorter mash length to streamline brew days, but a coarser crush in full volume BIAB just doesn't make sense. What are you trying to gain there?

 

[beervoid]

How fast are you running your mill? High speeds tend to produce fines even with larger roller gaps.

Have you tried conditioning the grain just before crushing? At least with roller mills (I don't know if it works with disc mills) it allows a tighter crush while preserving husk integrity - which in turns helps with lautering...

Cheers!

I go slow, aim for 100rpm. I've read experiments where the conditioning didnt make a.major difference on efficiency. I'm happy with 72% on medium to high gravity beers. I just dont get why this suddenly became a problem.

 

[beervoid]

You coarsened your crush (and inexplicably used two different crush gaps on the two batches) and shortened your mash length on the same brew day. Both of those are liable to reduce your efficiency. If you had finally achieved consistency with your process, why would you make changes to it? And for that matter, why make changes that are likely to hurt your efficiency? I understand a shorter mash length to streamline brew days, but a coarser crush in full volume BIAB just doesn't make sense. What are you trying to gain there?

I have been having trouble keeping stable mash temps and blame the slow recirculation for it.
After some reading on forums where people use similar systems widened grain crush was used to achieve better recirculation thus better mash temp stability and also higher efficiency.
80% efficiency is entirely possible according to accounts on this system.

 

[FatDragon]

I have been having trouble keeping stable mash temps and blame the slow recirculation for it.
After some reading on forums where people use similar systems widened grain crush was used to achieve better recirculation thus better mash temp stability and also higher efficiency.
80% efficiency is entirely possible according to accounts on this system.

Got it. That's out of my wheelhouse, then. I can say for certain that 80%+ in an hour or less is easily reachable with a fine crush, a couple stirs, and a small sparge in a low-tech BIAB system, and I've been in that range on my few no-sparge batches as well, which I'll only do if it's a pretty small beer for a very thin mash.. When you bring recirculation into the equation, my experience is nil.

 

[brewbama]

On my system, a finer crush resulted in less efficiency because I had compaction and channeling around the resulting tieg as I constantly recirculated throughout the mash. I also experienced stuck mash. I opened my mill gap to allow more grits vs flour which allowed the wort to permeate the bed running through it vs around it. I also thinned my mash and slowed my pump. The result was higher efficiency and eliminating stuck mash.

This is my reference:
http://www.craftbrewersconference.com/wp-content/uploads/ImprovingBrewhouseEfficiency-Havig.pdf

Episode 079 Brewhouse Efficiency for the Small Brewer
https://www.masterbrewerspodcast.com/079

 

[beervoid]

On my system, a finer crush resulted in less efficiency because I had compaction and channeling around the resulting tieg as I constantly recirculated throughout the mash. I also experienced stuck mash. I opened my mill gap to allow more grits vs flour which allowed the wort to permeate the bed running through it vs around it. I also thinned my mash and slowed my pump. The result was higher efficiency and eliminating stuck mash.

This is my reference:
http://www.craftbrewersconference.com/wp-content/uploads/ImprovingBrewhouseEfficiency-Havig.pdf

Do you have a grainfather like setup?
Which crush size did you settle on?
How long do you mash?

I was alarmed as well that most people seems report having no problems mashing adjuncts up to 20%, where as in my system just a little has a big impact on recirculation.

 

[brewbama]

Do you have a grainfather like setup?
Which crush size did you settle on?
How long do you mash?

I was alarmed as well that most people seems report having no problems mashing adjuncts up to 20%, where as in my system just a little has a big impact on recirculation.

As I indicated in post #3 above, I do not use a Grainfather like system. I mash 90 min: I measured SG every 20 min and was still getting an increase in gravity at the standard 60 min so I continued to mash until I no longer measured an increase.

I believe everyone’s system is unique to a point that an optimal setup like a certain mill gap, or pump setting, etc will vary system to system. Simple experiments over several batches led me to my settings.

 

[beervoid]

As I indicated in post #3 above, I do not use a Grainfather like system. I mash 90 min: I measured SG every 20 min and was still getting an increase in gravity at the standard 60 min so I continued to mash until I no longer measured an increase.

I believe everyone’s system is unique to a point that an optimal setup like a certain mill gap, or pump setting, etc will vary system to system. Simple experiments over several batches led me to my settings.

Right sorry missed that.
Thanks for elaborating. I have to conclude it was the shorter mash time that was the cause of this lower efficiency.