Low mash efficiency, course crush?

[SmokeyRydr]

I got a grain bill & crush at LHBS. My mash efficiency was super low: 57%, that's alot less that my typical 75%.

I suspect the crush was off. I didn't check before mash but in looking at the spent grains and they seem really course...

Any thoughts on this crush from the looks of it?

 

[Gnomebrewer]

It looks coarse, but I can't see any whole grains amongst it (it's hard to tell though, some of them might look whole, but when rubbed between fingers will fall apart, so they are actually crushed). A coarse crush might take longer to mash, but won't affect efficiency if you mash for long enough. Thus, if you mashed for the typical 60 minutes, you might not have got the same efficiency as if you'd mashed a finer crush for 60 minutes.

In the future, rather than mashing to a timeframe, mash until the mash is complete. Providing there aren't any un-crushed grains, you can always get around 100% conversion efficiency, your mash efficiency (into the kettle) then only depends on your sparge.
To check if the mash is complete, use this spreadsheet
http://braukaiser.com/documents/efficiency_calculator.xls
It's a bit of work, but worth the effort. FWIW, I find a temperature rest at about 160F really helps complete the mash.

 

[SmokeyRydr]

It looks coarse, but I can't see any whole grains amongst it (it's hard to tell though, some of them might look whole, but when rubbed between fingers will fall apart, so they are actually crushed). A coarse crush might take longer to mash, but won't affect efficiency if you mash for long enough. Thus, if you mashed for the typical 60 minutes, you might not have got the same efficiency as if you'd mashed a finer crush for 60 minutes.

In the future, rather than mashing to a timeframe, mash until the mash is complete. Providing there aren't any un-crushed grains, you can always get around 100% conversion efficiency, your mash efficiency (into the kettle) then only depends on your sparge.
To check if the mash is complete, use this spreadsheet
http://braukaiser.com/documents/efficiency_calculator.xls
It's a bit of work, but worth the effort. FWIW, I find a temperature rest at about 160F really helps complete the mash.

Thx, In hindsight, I should have just pumped the wort back into the MT and let it go longer.

Most looked to be cracked, but there were a good amount that were not cracked at all. Maybe 15%of the sample I grabbed weren't cracked.

 

[Gnomebrewer]

15% uncracked is really poor - I'd be complaining to the LHBS about that. That's an instant 15% efficiency drop.

 

[SmokeyRydr]

It turn out pretty poor. The finished porter is really thick and has a muddy mouth feel.
Almost undrinkable

 

[SoCal-Doug]

One of the best investments you can make is a mill. For numerous reasons.

 

[SmokeyRydr]

One of the best investments you can make is a mill. For numerous reasons.

No doubt. But the fact that I didn't examine the crush until after mashing was an operator error.

 

[SoCal-Doug]

No doubt. But the fact that I didn't examine the crush until after mashing was an operator error.

And that is exactly how we become better brewers! You will now always be aware of your crush