How fine is too fine for a BIAB grain crush?

[NeoBrew]

I've got a few BIAB brew days under my belt. So far I'm really happy with the improvement over my extract brews. A few weeks ago I bit the bullet and invested in a Captain Crush grain mill. I have been double crushing with a second roller gap of about .030. I have been running it through twice. My crush looks pretty fine with quite a bit of flour in it. I don't have a lot to compare it against since I've never used a traditional all grain setup.

I also just picked up a bottle of iodine. I was surprised to see conversion seems to be done in under 15 minutes. It actually looks pretty complete in 5 with just some darkness around the grains. I've been doing 60 minute mashes regardless with a dunk sparge to rinse the grains. I've gotten Mash efficiency of 87% and 93% with this method. (per Beersmith calculations)

I've had an interesting flavor in my all grain brews that I can't quite place. There is a strong aroma that I have associated with graininess or an "earthy" aroma. Some people say they really like it. For me it's a little out of balance in terms of it's intensity. It does seem to lessen after a few weeks in the keg. One person told me they prefered it after it sat in the glass for a while. I would certainly like to identify it so I can at least be in control of it.

Here's my questions:
1. I know fast conversion isn't a problem. Are there pros and cons to continuing the mash for 60 minutes? Do I get additional flavors or more fermentable wort? Do I risk tannin extraction?

2. Would I benefit from crushing a little coarser? I am not having clarity issues as Whirlfloc and settling in the pot give me fantastic clarity into the fermenter. Are there flavor or fermentability benefits? I've heard efficiency in the upper 80's and 90's can lead to tannin extraction. Is this true for BIAB?

So much of the information out there is about a traditional mash tun approach. It's hard to determine which of the information applies to BIAB.

 

[Conestoga]

You may find what you are looking for in this thread. Read post #10 and on.

https://www.homebrewtalk.com/f244/missed-my-sg-mark-alot-473154/

 

[chitowngator]

My first thought was water profile. The first couple batches of BIAB I did had a grainy taste to them that went away once I started adjusting my water profile and mashing pH. It looks like New Brighton has "very hard" water according to their website. Any chance you are using water from a water softener?

 

[NeoBrew]

Yes, my city has really hard water. I'm using RO water which passes through my water softener first. This is reported to help preserve the RO membrane. It's coming up on 8 years old and I'm still getting 8 ppm total dissolved solids. I've been considering sending in a sample of my RO water to Ward Labs so I can know what I'm starting with.

For the last few batches I've been using Bru'n Water. None of those batches have made it to a glass yet, so we'll see if that helps. Prior to that I was using the calculator in Beersmith. I have not invested in a PH meter yet. I would imagine I'll get there sooner rather than later though.

Based on those referenced threads, I think I'll dial my mill a notch wider for my brew tomorrow. We'll see if that helps.

 

[FatDragon]

Try the coarser grind so you can come to your own conclusion by experience and not just following the advice of others: there are plenty of different opinions out there because different techniques work better for different brewers. I crush fine because I get better efficiency that way and don't seem to be extracting tannins (unless I'm just not tasting them), but if you can get good efficiency with a coarser grind, all the better.

 

[pigroaster]

I see your are doing the BIAB technique but I would use a laundry sprayer and spritz your grain with a fine mist 20 minutes before rolling. Use about 1 oz water per 10 lbs grain. This will allow less damage to the husks and do a fine job at .030 gap. Watch your water temperatures. Mash in at 152-154 and get your bag out before 180 Fwhen you raise your heat or you will have tannin issues from the husks. The more intact they are (husks), the less problems you will have.

 

[ram5ey]

The husks aren't going to give you tannins if you don't sparge and they stay out of the BK. The tannins would come from higher PH sparge water.

 

[NeoBrew]

I can see there is a balance. I've been doing a dunk sparge and getting great efficiency, but if I ground more coarse the grain bag would drain better and I might not need to sparge at all.

I'm in the mash right now. I didn't try moistening this time. I did a double crush with the lower roller at .040. After the first grind the hulls were separated nicely and the hulls were pretty much whole. After the second one the husks were broken up quite a bit more. There was certainly some areas that were pretty fine, but overall there was a particle size that was under about 1/16".

Here's what it looked like.


I think next time I might tighten the mill down to .024 and do just one crush. If I can get the grains through I think it might leave the hulls more intact.


Sent from my iPhone using Home Brew

 

[unionrdr]

I use the Barley Crusher grain mill set at the factory notches of .039". Even if grains are pre-crushed,I crush'em again at that setting. My efficiency is quite good,as I've gotten OG's of 1.060 & 1.061 out of recipes that were 1.045-1.049. I'm finding that the less floury stuff you get from your crush,the better. And I do pb/pm biab.

 

[jbaysurfer]

That's WAY too fine IMHO. The husks are generally supposed to be intact. I think your setting should either be a 1 pass setting or you should readjust to .038 and double pass it (also condition it as described above 1oz per 10lbs, have a helper slowly pour the grain into a second bucket while you spritz it).

Generally unless you get a lot of debris into the boil kettle you're not going to extract "grainy" tannins..but with that crush, you're almost guaranteed to get a lot of debris in the boil kettle....all IMHO. Hope this helps. I do great when I BIAB and double crush (after conditioning) at .038.

 

[RM-MN]

That's way to coarse IMHO. That grain still has chunks in it and your husks are mostly intact. My milling leaves me with smaller particles and the husks are torn to shreds.

You'll get a lot of debris in the boil kettle. Unless your pH is too high you won't extract any more tannins than if you had whole grains. When the yeast are finished the debris will settle to the bottom of your fermenter.

 

[RM-MN]

This is what my milled grains look like.

 

[NeoBrew]

I think your setting should either be a 1 pass setting or you should readjust to .038 and double pass it...

Generally unless you get a lot of debris into the boil kettle you're not going to extract "grainy" tannins..but with that crush, you're almost guaranteed to get a lot of debris in the boil kettle....all IMHO. Hope this helps. I do great when I BIAB and double crush (after conditioning) at .038.

The crush in my pictures was at .040 and double crushed. So I don't think going larger is going to be a good idea. I will definitely try conditioning the grain next time.

As I think about this, your suggestion that getting material in the boil kettle will extract tannins is my front runner theory. I really doubt I'm getting much husk in there though. I'm using a voile bag and it does a great job of holding anything but particles too small to see. I'm sure some flour is getting in there though. My wort is definitely cloudy when I start the boil. I've been resting comfortably in the reassurance from other BIABers that settling that stuff out post boil and in the fermenter means it doesn't affect the beer. I've had great luck getting pretty clear wort into the fermenter by using whirlflock and settling in the pot for a few hours before transferring.

RM-MN, It's hard to really see what's going on in your crush to compare against mine. I do have a lot of flour mixed in with the larger chunks. Your's seems to be more consistent in size than mine. Perhaps adjusting both rollers a little tighter and going for a one pass crush will help.

Oh, and I got 85% mash efficiency today according to Beersmith. I think that seems a reasonable number.

 

[RM-MN]

If you got 85%, your crush is fine. My grains are milled on a Corona style mill which is probably why the size is more consistent. How long do you let your mash set? With the bigger size particles it should take your mash longer to complete than mine. My mash, as evidenced by iodine test, wort clarity, and the apparent attenuation, is over in less than 10 minutes so that's when I've been pulling the bag out of the boil pot and starting to heat the wort.

 

[NeoBrew]

I've been doing full hour mashes just to make sure everything that can convert has. Today I still got a little bit of a dark iodine test at 20 minutes, by 40 it seemed to be done. I let it go the full hour just to be sure.

What are the pros and cons of pulling the bag vs leaving it in? Flavor? A minor amount more conversion? I would think that you would get moisture deeper into the granules and get something more out of it.

 

[816North]

I have used actual bread flour without issues. It's not pretty but it worked. I had 20% by weight. It was whole wheat flour.

 

[jbaysurfer]

I think your crush is too fine as well RM-MN, but then again, if it works for you, I wouldn't change a thing!

I would definitely get a stuck mash if I did that batch or fly sparging, but alas that's a different topic.

I did a google image search for proper crush, and they run the gammut. But the idea is for the husks to be left mostly in tact while the endosperm is exposed (not neccesarily crushed into a flour). Mostly this is for setting the grainbed when vorlaufing and for clean sparging, but it could affect BIAB by letting husk particles through. I do both BIAB and batch sparging, and for me personally, having more intact husks works better for both.

I do recognize that a Corona mill is going to tear the husks apart due to it's design too fwiw.

Again though, cheers to all you guys and if you make good beer your way, more power to ya!