SPENDING MONEY TO MAKE MONEY - AN OVERVIEW OF MASH FILTERS
HI ALL,
Let’s keep this Mash Ball a’rollin’ with a little discussion of a fairly rare, but super cool, piece of brewing tech called a mash filter. While not too common in the craft brewing scene, it’s an interesting approach to mashing that can raise efficiency from, oh, 80% say to a staggering 98%+, which allows you to use a good deal less grain without any quality loss, and as an added bonus specific to the device, conduct otherwise very unwieldy 100% non-Barley mashes (we’ll discuss why that’s kind of nuts shortly). But in order to dig into the advancement made with this device, we should start, once again, at the beginning.
THE GIST OF THE GRIST
(Note: if you can tell me the difference between fly and batch sparging, you can skip to “Why Efficiency Matters…”)
As we’ve discussed before, mashing is the process whereby you combine crushed malt and hot water, let them settle to some target temperature, possibly raise that “mash” to a few more temperatures (which is fairly rare on the craft scene these days for largely good reasons), and then, after an hour or so, somehow separate out the liquid “wort” from the spent grains. It really is quite a simple process once you’ve dialed in your grain mill, especially these days, since readily accessible software can with impressive accuracy estimate the temperature of this grain and water slurry, given initial quantities and temperatures. And while the whole process is interesting and worthy of discussion (see, for example, this book or this one), today we’re focusing on that last step, the separation of the wort.
A BRIEF SURVEY OF WORT SEPARATION METHODS
The mechanism by which you separate the spent grains from the wort can be quite simple, and indeed, all of the modern methods (aside from the mash filter) are quite rudimentary at their core. Here’s a brief list:
Brewing in a Bag
On the homebrewing level, you can literally just add your grain to a food safe mesh bag, lower that into water, and then pull it back out when you’re ready to boil
Tubing-based Manifold
I have no idea how common these are these days in commercial brewing, but a fairly common home-made mash manifold (one name for the wort-separation...manifold) is a system of copper tubes, wherein cuts are made in the tubes to allow wort to pass through them, but not the grain and husk matter, like in this guide
False Bottom
The most common design is just a flat, fairly thin plate of stainless steel (let’s say a millimeter or so), wherein small holes (let’s say a millimeter or so) have been drilled at regular intervals to, you guessed it, let liquid through without letting malt through
Mash Filters
See below!
And that’s kind of it. I love the idea of using some gelatin mesh to trap the particulate matter, or using a centrifuge or something, but no, these simple mechanisms work well enough that there hasn’t been much improvement in a few hundred years (stainless steel and the widespread use of metal in brewing being a singular, tectonic shift from this insanity - and yes, of course I’ve been there. Have I not mentioned 1786?).
Oh, and one more technical note before we move on: there’s a limitation implicit in these methods that’s worth outing, which is most easily posed as a rhetorical question: what would happen if you were to try and lauter (the process of wort separation) brioche dough? Yeah, it would be a nightmare. This isn’t all that hyperbolic of a scenario, since while malted Barley comes with a husk, that is then shredded (not torn or pulverized) by milling, providing a crucial natural sieve of sorts between the crushed kernels of starch (read: endosperm), grains like Wheat don’t come with such a boon, and as such a common response is to actually add rice hulls in order to add back that natural filtering, or to limit wheat to a small enough percentage of your “grist” (i.e. malt “bill”...er, recipe) that that’s unnecessary. If you don’t think this would make a huge difference, I welcome you to give even a 50% Wheat beer a shot without rice hulls. I recently did just that, and, since my mashing regime involves essentially two draining steps, the second step, where I added hulls, went, I don’t know, five times faster? Ten times? Much faster, in any case, with zero downside.
WHY EFFICIENCY MATTERS, AND AN EXTREME SOLUTION
Alright, we’re almost talking about mash filters, just hang in there, sport. One last hurdle, I promise. I’ll keep it brief.
Mash efficiency is equal to the amount of sugar that you got out of your grains divided by the theoretical maximum (we might talk about that in a future post), and my personal system runs in the 65%-75% range, meaning every lb of grain yields 12 oz’ worth of sugar. Why is this important? Money. There is virtually no downside to seeking higher efficiency, and the less grain it takes to make identical beer, the better, so you want the highest efficiency possible (and for the mash, that means 100% is the goal - there’s actually a limit for continuous sparging, because you begin to pull unwanted flavors from the grain at a certain point, but that’s irrelevant in mash filters apparently).
And that’s where mash filters come in.
The idea behind a mash filter is kind of insane in its simplicity - in order to maximize yield and minimize mash times, why not mill the malt, or even raw grains, into a powder, and make some brioche dough, hold the glutenin matrix? Well, as mentioned, good luck setting that over a sieve and expecting wort to precipitate out. But what if you pushed on a very loose “dough” with a flexible bladder filled with compressed air? Well, yeah, that turns out to work.
In 1901, a madman by the name of Phillippe Meura invents the mash filter, which is essentially a long tube of these bladder-filled mash cells (actually, apparently only every other cell has a bladder), capped with polypropylene filters, in which you pump your mash, press it to extract the wort, and then dump the nearly-dry spent grain. This is...pretty gangster. As I’m sure you can guess, it’s way more expensive than a normal mash tun (without getting a quote from a manufacturer, I’m not sure by how much), and is a pretty rare find in the US, but there are several advantages, notably:
Crazy high yield. Did I mention that 98% figure already?
This can be viewed as the ability to brew the same beers with less grain, which is more cost effective and environmentally friendly
The ability to conduct more mashes per day
This article mentions a total of 45 minutes from some step to an empty mash tun, but is that from mash in (when you add the grains), or from the end of the mash? Does the mash go that much faster due to the crazy high surface area-to-volume of malt flour versus the granules of traditionally milled malt? It’s unclear from the wording
Efficiency overall means less water usage
Indeed, if 100% of your sparge water is used and you end up with dry spent grain, you’re bound to use less water, which is, again, better for the environment (I suspect that if these get cheap enough, they’ll be near-universally adopted within, say, 50-100 years; for reference, the edges of Manhattan and parts of Brooklyn are underwater in about 30)
Dry grain is easier to handle
Forget shoveling fully hydrated grain out of a milk tank by hand, with these bad boys, dry spent grain falls out of the plates in sheets. That should buy the farmer you give your grain to extra time as well, since spoilage should take longer. Plus, it’s bound to be a morale boost, and present yet another time savings
Are there any downsides? They’re not too significant, but:
Cost
It costs a lot. If you brew enough batches, this additional cost is amortized (I just took an accounting class, if I can use that word, I will), so it’s really just a cash flow issue if you have the money
Apparently, the range of mash sizes is small
So it seems like you couldn’t, say, run a 5 BBL mash in a 7 BBL system, like we could theoretically do now (though never have - so is this an issue? Only if you grow, I guess)
Oh, and are tannins a thing?
Apparently the speed of this system may help mitigate that (remember that sparge limitation I mentioned? Yeah, you can’t extract every gram of sugar in malt because you’d start pulling silicates and tannins from the hulls, which milling to flour should exacerbate, but again, apparently that’s not a tangible issue)
CONCLUSION
I can see a few punchlines here, but my favorite is this: if you’re an industrial engineer, there may be boatloads of cash to be made in designing a cheap ~7-15 BBL mash filter for craft brewers. In the meantime, they remain an insanely cool, if unjustifiably expensive, piece of future-tech to drool over and dream about, like a Personal Computer in the 70s
Cheers,
Adrian “Build a one gallon mash filter, I dare you” Febre
------------------