crush size...larger/coarse but mash longer?

[odie]

What about just using a "standard" 3V crush size but mashing longer? say a few hours? would that result in the same mash efficiency as a fine crush in only an hour? And would a coarser crush allow the bag to drain better and more completely? I ask cause lately I've been mashing before work and letting it mash all day so a "fast conversion" is not required. Just a "complete conversion"

It seems there are two separate things we want to accomplish in the mash.

First is to convert as much starch as possible into fermentable sugars. A tighter crush will happen faster and almost, if not 100%. But if left for a few hours would a larger crush eventually reach total conversion?

Second is to get as much of the wort out of the bag. which retains more wort? A bag of coarse or fine crush? Which drains slower? Doesn't a tight crush plug the bag more? What drains faster? gravel or sand?

 

[bracconiere]

i don't BIAB, but i'd say if you go coarse you'd have to sparge more....because the converted sugars will be in the grain.....(or with my limited knowledge, sparge at all)

 

[jdudek]

I am in a similar situation where with the work from home COVID situation I just mash during the work day without any set schedule... (could mash 2 hours, could mash 5). lift the bag towards the end of the work day, set the temp controller to 205 and come back to finish the boil after the kids are in bed. Anyway. I did a few batches with fine crush (0.024) which converts full in under an hour, but the last one i did at 0.045. It took ~2 hours for full conversion. Without coarser crush bag drained a lot easier than the fine crush, though i just usually squeeze until i hit the volume i am looking for as opposed to trying to get every last drop.

My goal at the moment is to get something that recirculates reliably for an undetermined amount of time, so that i can keep a constant temperature for these long mashes. Brewing another batch this friday with a 0.045 crush and some rice hulls. Happy to report how the conversion went this time.

Maybe the way to go is to crush coarser but not all the way coarse and see what you get and go from there? 0.045 seemed like a good compromise between crush size and fluidity. But i may adjust, I'll see how the next few batches go.

 

[silveiradaniel]

Having tried both ways I've now settled for 'as fine as possible' when crushing malts at the shop... first because they have a very fancy machine that does the job and second because it seemed to suit better mash efficiency. I wouldn't like to leave it there for much longer than 1 hour anyway and truth to be told efficiency-wise 45 min seems to do the job and results in good beer to my taste.

Mind that my setup is very simple (some pictures): burner, 6-gallon pot, 2 fermentors, bag, temp + densimeter.. no fridge, just ice bottles inside a cooler. I mash at the recipe's temperature and do place the bag with pre-squeezed grains inside the fermenter once more with 75 Celsius water (about 167 F) for 10-15 minutes with a few shakes to get more sugars out of it and once this is done I proceed to a proper squeeze. Don't do mash-outs anymore, don't see any difference. After boiling for recipes time wort goes back to fermenter immediatelly for an overnight no-chill and next day yeast finds its way to finish the job.

 

[odie]

well I figured a finer crush lets the hot water reach all the starch faster to convert it. But if it's sitting in hot water for several hours, then isn't all the starch going to get converted anyway? Even the bigger pieces? Just seems a finer crush somehow holds more wort in the bag when you pull it. Or do the larger pieces retain more wort inside the pieces?

Assuming you have complete conversion either way, which will result in the most fermentable sugars draining to the kettle when pulling the bag?

Is it that fine crush converts more starch to sugars in the mash, but larger crush drains/lauters more sugary wort to the kettle?

I guess I need to do two identical 1/2 BIAB mashes at the same time and then compare the resultant wort volume in the kettle and SG.

 

[jdudek]

according to Palmer:
http://howtobrew.com/book/section-3/getting-the-wort-out-lautering/a-good-crush-means-good-lautering
There is a trade-off between particle size and extraction efficiency when mashing crushed grain. Fine particles are more readily converted by the enzymes and yield a better extraction. However, if all the grain were finely ground you would end up with porridge which could not be lautered. Coarse particles allow for good fluid flow and lautering but are not converted as well by the enzymes. A good crush has a range of particle sizes that allows for a compromise between extraction and lautering.

So if lautering efficiency goes up with crush size, then one would think you'd get more liquid out of the bag with a coarser crush... ?

 

[odie]

So what has a higher grain absorption? Tight or coarse? which would naturally drain the most volume without sparge/lautering?

Does a tight crush have a higher starch conversion or just a faster conversion? Does a coarse crush leave starches unconverted or does it just take a couple hours longer to reach the same conversion percentage?

BIAB crushing/mashing methodology seems to be based upon trying to keep with a standard mash time (60-ish). If you have several hours to mash does that open up efficiency possibilities not normally explored?

 

[LittleRiver]

I crush at .025", mash for 45-60min, hoist the bag and let it hang it drain over the kettle for the entire boil. I don't sparge, I don't re-circulate, and I don't squeeze the bag. With this simple and enjoyable process I get BH efficiency that is consistently in the low 80's.

Higher OG brews do cause a hit on efficiency, so I sparge if I'm shooting for an OG that is above 1.065 (which is very rare for me) this way:

• mash with 50% of the total water
• drain the wort into a bucket, leaving the bag and grains in place
• add the second half of the water to the grains, stir thoroughly, then raise the bag
• immediately fire the heat for the boil; leave the bag draining over the kettle for the entire boil

 

[RM-MN]

well I figured a finer crush lets the hot water reach all the starch faster to convert it. But if it's sitting in hot water for several hours, then isn't all the starch going to get converted anyway? Even the bigger pieces? Just seems a finer crush somehow holds more wort in the bag when you pull it. Or do the larger pieces retain more wort inside the pieces?

Assuming you have complete conversion either way, which will result in the most fermentable sugars draining to the kettle when pulling the bag?

Is it that fine crush converts more starch to sugars in the mash, but larger crush drains/lauters more sugary wort to the kettle?

I guess I need to do two identical 1/2 BIAB mashes at the same time and then compare the resultant wort volume in the kettle and SG.

Look up how caramel malts are made. That will answer the first part of your question. Then think about putting some caramel malt in your mash without crushing them and about how much of the sugars you can extract that way. There will be a tradeoff between fast conversion and lauter efficiency and between full conversion and haw fast the wort will drain. If you only want full conversion you can trade off time and the fineness of the crush. If you want high brewhouse efficiency you trade conversion time and how well the mash will drain.

 

[Gnomebrewer]

What about just using a "standard" 3V crush size but mashing longer? say a few hours? would that result in the same mash efficiency as a fine crush in only an hour?

Yes, it certainly does. You can use this spreadsheet http://braukaiser.com/documents/efficiency_calculator.xls to work out when your mash is approaching 100% efficiency (i.e. all sugars are extracted and converted). I use a reasonably coarse crush on my system simply because my mill doesn't work any finer - it typically takes about 75 to 90 minutes to get to about 95% efficiency in the mash. If I use a fine crush on my corona mill, mashing finishes in about 30 minutes. Just watch out for whole (uncracked) grains - they won't work in normal brewing timeframes. As for draining the bag more or less completely....I have no idea, but the coarse crush should drain faster.