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Double Crush?

Post #1 made 10 years ago
by smyrnaquince
So, what is the current thinking on double-crushing grain?

I crush at the LHBS using whatever roller setting they have, which would be set for 3V brewers. When I first started BIAB 2 years ago, I started double-crushing the grain. The reasons were supposed to be at least one of:
  • Raise the efficiency to make up for the BIAB method
  • Get additional efficiency because BIAB will allow you to do a finer crush
At this point, I am wondering if it makes sense to double crush because:
  • The efficiencyis/might be fine without it
  • The smaller particles may make it through the bag, thus getting tannins or other undesirables into the wort
(Regarding the last point, it seems to me that one of the biggest differences between BIAB and 3V is the lack of a vorlauf. If I have it right, the 3V-ers drain the wort through the grain bed until it runs clear (the grain bed has established an effective filter), then pour that cloudy stuff back onto the grain to also be filtered. With BIAB, that first cloudy bit makes it into the boil.

What is the prevailing wisdom? Double crush? Don't bother?
Last edited by smyrnaquince on 27 Jun 2013, 01:33, edited 2 times in total.

Post #2 made 10 years ago
by Yeasty
I think its been agreed that a normal crush is adequate for Biab and that double crushing to achieve a finer grist is not required. As long as your crush results in all your grain being cracked/broken/split with a small proportion of flour your efficiency will be fine. The key point is that you want the inside of the grains to be in contact with your water some way or other. I buy my grain in 25kg sacks pre crushed at the mill and my efficiency's are 80%+ for an 1.045 OG brew.

:salute:

Yeasty
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Post #3 made 10 years ago
by Mad_Scientist
I single crush mine myself and get efficienicies, 80+, even with doing a MAXI (just a little water held back). I don't know about particles getting past voile fabric.
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Post #4 made 10 years ago
by BobBrews
A single crush with a 90 minute mash is more than adequate. It doesn't take that much time to re-crush grain so if it makes you feel more confident do it!
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Post #5 made 10 years ago
by smyrnaquince
In previous recipes, I double-crushed, but you guys convinced me that this is not necessary.

For my latest brew, I meant to single crush, but mistakenly sent the grains through the crusher at the LHBS that is meant for steeping grains and has a larger roller gap. I then sent them through the correct crusher, so I guess I consider this a one-and-a-half crush.

According to BIABacus, the predicted Efficiency into Kettle was 87% and I got 84.8%. Quite reasonable, I'd say, and within the error bounds for how accurately I can measure the gravity and volume.

Post #7 made 10 years ago
by smyrnaquince
I agree that my EIK was just fine. I don't really chase the numbers. I do with efficiency what I do with my car mileage. I check the mileage at every fill and the efficiency at every brew. If the numbers are more or less what I'd expect, I'm happy. If they are significantly off, it tells me to look for a problem.

Three brews ago on a witbier, I had around 71% EIK, where I typically get in the 80's. I brewed the same recipe a month later. The second one was an experiment I had planned to adjust the water profile to bring the pH down (and the calcium up). I also went back to my usual stirring of the mash every 15 minutes, which I forgot to do on the first one.

According to Bru'nwater's predictions, my unadjusted mash pH was 5.7 and in the second brew it was 5.3. Half the recipe was flaked wheat and flaked oats, so I suspect that the lower pH helped the enzymes do a better job.

The 1st batch EIK was 71.4%, the 2nd was 86.1%, both calculated with the actual ppg's for the grains. Both were 90-minutes mashes.

The stirring may have made a difference, but I think the pH was the biggest factor.
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