Looking for input on experimental procedure

[stratslinger]

I've been thinking about running an experiment for a little while now, and I think I'm just now really well equipped to do it.

I'm a more or less traditional three vessel all grain brewer. I've read advice stating that you should mill your grains as finely as possible, and others stating you don't want to go too fine. Half the guys in my brew club subscribe to the theory that you should do two passes: one with a wide gap on your mill, and one with your final, more narrow gap - but that gap is not as narrow as some I've seen recommended here on hbt. My own anecdotal experience has seemed to indicate that too narrow a gap hurts my efficiency, while a slightly more open one works better - though it haven't bothered with the two stage milling process.

So, enter my experiment: using my 3 gallon cooler mash tun, I want to take a typical 6 gallon recipe and divide it up into 4-6 smaller ones, each one identical in makeup but only milled differently. My aim is to mash and sparse into one vessel, take a gravity reading, and then add the contents of that vessel to my normal BK so I can proceed with the brew as normal once I have my full boil volume set to go.

My one concern: since this will take a number of hours, do I need to be concerned about the first couple of batches potentially spoiling before I'm able to start boiling? I'm also an electric Brewer now, and I need about 4.5 gallons in my BK to submerge my element, so it'd be some time before I could introduce heat... Should I be concerned, or should this work out alright?

 

[kombat]

Let me save you some time: Mill gap setting affects your efficiency. Too wide a setting, and you'll have some degree of uncracked grains, where their starches will remain unreachable, and your efficiency will be low. Too narrow a setting, and you'll end up with fine flour that will impede draining your wort from the mash tun. You'll open the valve to drain the liquid and only get a trickle. You'll open the lid and see a puddle of wort pooling on top of the grain bed, refusing to drain down through the mash ("stuck mash/sparge"). The sweet spot is somewhere in the middle. The goal is to mill the grain as finely as possible, but not so fine as to cause the dreaded "stuck mash/sparge." Experience shows that this setting is between 0.035" and 0.040", or about the thickness of a credit card.

 

[govner1]

^^^THIS!
The only reason to mill twice is if your gap setting is off & your original crush leaves too many in milled grains (old maids).

 

[IslandLizard]

Sounds like a good experiment!

My thoughts:
I would mash in a large pot and stick it in a preheated, turned off oven to keep mash temps closer to ideal. After the mash is done, stir well, lauter some off, measure gravity, that's the first data point. Heat it up to 170°F and hold for 10-15 minutes for a mash out and chuck that mash in your large mash vessel, waiting for the others. Repeat for the other grist tests.

At the end, lauter and sparge the whole mash vessel. Continue your brew as usual.

You do need to measure your strike volume of each test mash with some accuracy or you can't draw any conclusions on efficiency.

Required grist coarseness is dictated mostly by your mashing system. A fly sparge needs a good lush grain bed. Batch sparge is not as demanding, and BIAB uses the bag as a filter, the grist can be very fine, with lots of powder.

The finer you mill, the faster the gelatinization and conversion, the easier to rinse the sugars from the grain bits, and possibly the higher the efficiency. Mill too fine and your mash will plug up. So strike a balance between conversion speed and lauterability while maximizing efficiency.

 

[IslandLizard]

^^^THIS!
The only reason to mill twice is if your gap setting is off & your original crush leaves too many in milled grains (old maids).

Sadly, that's the common LHBS approach and a fallacy. Milling twice on a gap that's too wide is no substitute for milling once on the correct gap. You can even extend that thought and argue that different size kernels require different gap widths. I find that true: wheat and rye kernels are much smaller than barley so to crush them properly, you do need a narrower gap than the one used for barley.

 

[madscientist451]

To save you even more time, check out the Brulosphy experiment that did the same beer with different mill settings:

http://brulosophy.com/2015/11/23/mind-the-gap-course-vs-fine-crush-exbeeriment-results/

 

[stratslinger]

Let me save you some time: Mill gap setting affects your efficiency.

Thanks - but I think this is a given. The point of the experiment is not necessarily to identify whether a gap setting will affect efficiency, so much as to identify an "ideal" gap setting.

When I first got my own mill, I followed much of the advice I found here on HBT, and I was getting lower than expected efficiency (mid-60's was pretty typical). I don't remember the setting for sure, but I think it was around .032". At that point, a few of the guys in my club suggested I had the gap too tight, and I loosened it slightly - I've been at about .037" ever since, and once I combined that with going to fly sparging, I typically get around 80% efficiency. And still the other guys in the club insist that if I run it through once at .060" (or something in that neighborhood) and then again an .037", I'll do even better. (This just doesn't sound right to me.)

What I'd like to see is if I can zero in on what setting gives "good" efficiency, and prove/disprove the idea that premilling at a larger gap makes any difference.

So, that still begs the question: If I do, say, 6 individual mashes over the course of a day (I'm limited in that I only have a single small mash tun - but I want them all to use the same equipment anyway to eliminate as many variables as I can), will the wort produced by the first handful of mashes be at risk of spoiling before I can heat it in my BK, since it'll be sitting there (covered, at the very least) for 2-3 hours before I can apply heat.

I like the idea of putting it into the oven, but I don't think I have a pot that is both large enough to hold 3-4 gallons of wort and small enough to fit into my oven.

If I were to just put it all into my larger cooler mash tun, it would go a long way towards maintaining most of its temperature. Would that be enough, do you think?

 

[IslandLizard]

Perhaps the idea of the wide gap / narrow gap sequence is to keep more of the hulls intact, possibly simulating a 3 roller mill?
Instead, you could try to wet-condition your malt before crushing. It makes the hulls more supple, so they won't pulverize/shred as much.

Now that Brulosphy exbeeriment hints that finer crush gives better mouthfeel and fuller flavor, at least to that RIS...

To prevent your test mashes from converting too far, while waiting for the others, do a mashout on them. I mentioned that before. You can either keep them, then lauter/sparge the whole lot or waste time doing them individually. Keep the mash covered tightly with some foil or plastic bag while it's waiting.