Adventures in Home Malting - Beer, Wine, Mead, & Cider Brewing Discussion Community.

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When I first started reading about brewing in earnest, I noticed that the words written about malting were rarely favorable, more often veering toward discouragement. Tedious, labor-intensive, and lengthy were the consensus; it requires too much space and immaculate hygiene, said home-brewing manuals, when they touch on it at all. Yet the importance of the malt house stands out in history: Anheuser-Busch and Rainier were breweries which started—as many did, from necessity—as both breweries and malt houses (Similarly, Pacific Brewing & Malting Co. of Tacoma, Wa., holds a historic name without a single grain being sprouted in its current operation). The original role of the community brewer was to take grain, as a raw product of agriculture, and turn it into a stable, storable, and cheer-inducing commodity: so what happened?
In order to investigate (and fulfill my constant urge to do things other people say not to) I decided to give home malting a go. Over the last year-and-a-half of sprouting, kilning, and reading I have accumulated some resources and experience which might be useful to anyone else who dares tread upon the malt-roads, dis-used as they may be. But fear not, beer-farer! The dangers are much exaggerated, and any brewer might learn from a modest handful of grain sprouting on a tray. To help anyone curious navigate this process, I have compiled my notes into the following practical guide. I will not fully explain all of the terminology, the definitions for which can be found elsewhere. Further, I recommend the reader be familiar with the concept of modification in malt and the principles of adjunct brewing. The following sections are explanations of what helped, and what worked. Enjoy!


Malting is the process of starting to germinate a grain—the edible seed of a food grass. As the seed wakes up, it starts producing enzymes which begin breaking down the starches and proteins of the grain as food for the new, growing plant. The maltster then halts germination of the seed by drying, which preserves the enzymes and (modified) starches for the mash tun. Seems simple, right? It is. This guide will focus on barley, but the same principles apply generally to other grains.


Compared to the amount of information on brewing that an internet search will give you, there is not much (at the time of this writing) on home-malting. Some more comprehensive brewing books will have a chapter on it, and there are a few heroes who have posted videos on YouTube, forums and blogs. Post-prohibition books on malting tend to be either for industrial-scale maltsters or are supplements for the avid brewer. Instead, the books I found most helpful were older and available on Google Books for free:
The Maltster's Guide, by Edward Skeate White (1860)
The Theory and Practice of the Preparation of Malt and Fabrication of Beer, by Julius Thausing (1882)
There are others available, but I found these two most helpful. It's worth noting that Edward Skeate White was British, whereas Julius Thausing wrote in German (the version I linked to is a translation), and the two books represent the very different British and German malting traditions. But be careful, some of the science in these is completely outdated! They contain practical suggestions which are important to know, though, such as White's recommendation that the best malt is made by soaking barley in canal water for 48 hours (as yet untested by this author).

Home Malting Process

1: Sourcing grain
The raw ingredient any maltster needs is whole, viable feed-type barley. The best place to get it is from a farmer, but otherwise try a feed store. If you don't live in barley country, you might have to try a few! Garden/hardware stores which sell some feed are also a good bet.
Although not all barley is bred for malting, almost any barley can make good beer; that being said, avoid Haybit, or straw-producing varieties (as they have little starch). When selecting a feed-type simply look for something with fat, regular kernels. The fatter kernels have more starch and less husk for your money, and are more likely to be a 2-row variety. I've very rarely seen the variety noted on bags in stores, and one farmer I purchased from didn't remember that name of the type of barley he grew, so I couldn't tell you much about specific varieties!
BYOB (Bring Your Own Bag)
Beer is meant to be cheap, and barley is too. I've seen it sold from $.12/lb on the farm, up to $40 for a 50lb bag ($.80/lb) for organic barley in a garden store. I have been grateful for $10/50lbs, and accepted $20/50lbs. When you find a good source, they may also have wheat, rye, or rolled barley available for a similar price.
2: Soaking
The first step is to put the barley in a container and fill with water until covered. When I began, I started with 12lbs of dry grain in a 5-gallon bucket, and worked up to around 120lbs in a 55-gallon barrel. The goal is to soak the barley until it is saturated, or begins to 'chick' (white root tip appears at base of seed). Generally, the water needs to be changed multiple times over a several-day period to accomplish this. Barley needs oxygen, and if left in unchanged water too long will suffocate: it is also common to give it an 'air rest' between submersions. Each submersion is also an opportunity to clean the barley, as miscellaneous material will floats and can be skimmed off. I generally cover the barley in water before going to bed, drain it at some point in the morning and let it air rest for most of the day, then fill it again in the evening, over the course of three days.
Fillin' up a 55
3: Sprouting
After the barley is saturated, it needs be left to germinate. During this period the barley grows roots, produces heat, and consumes oxygen. It is necessary that it be kept aerated and that it still retains enough moisture to continue germinating. In small quantities, say 10lbs in a 2-inch layer, the grain might only need to be turned once or twice a day, with a quick mist of water to keep it hydrated, and it will be ready in 3-5 days or so at room temperature. For larger quantities (50+lbs) I recommend looking at Thausing's notes on how to work the grain through germination.
12lbs of grain germinating in an old drawer
120lbs of grain germinating on a tarp
The grain is ready when the length of the acrospire (or growth from the barley) inside the husk has reached between halfway and fully the length of the husk, serving as a rough indicator of enzymatic potential. An acrospire grown halfway produces a partially-modified malt, whereas a fully-grown but not yet emergent acrospire indicates full modification. The most important indicator of flavor change and brewing potential to me, though, is how the smell of the malt during this period changes-- early in germination the grain has a strong fruity smell, like old apples or cantaloupe, and as it modifies it changes to a grassy smell.
Note: There are a wide variety of environmental factors that will influence the timing of this process. It is essential for the home maltster to come to know the seed's metabolism as it wakes up and starts growing. In a warmer environment, these processes will happen faster, and the seed will also consume oxygen faster and respire more, therefore needing to be turned more often, etc. The reverse is true in a cold environment. The shape of soaking and germination containers will also affect this. Additionally to changing the grain's physical needs, these factors influence the flavor: for the record, classical maltsters prefer grain malted at very cool temperatures (40-50F). It is important to be aware of this, as in the literature the estimated soaking/germination times are relative to assumed low temperatures.
4: Couching/Withering
These two steps took me some time to figure out, as they are often left out of basic home-malting guides. Neither step is required, but both have effects on the finished malt. Also, although they are very different processes, they both have the effect of ending germination, so that it does not continue while the grain is kilning. Whether this is considered necessary is, as with many things, at the discretion of the maltster.
Couching is the process of putting the finished wet malt from the germination floor into a closed container for 12-24 hours so that it suffocates itself. I usually just returned it to my soaking barrel and put a loose lid on. Besides halting germination by killing the grain, the heat created by the metabolizing grain in a closed space causes some enzymatic activity that drastically changes the aroma of the malt. This step is, as far as I know, a unique but omnipresent aspect of British malting.
Withering is the process of thinning out the grain and blowing cool air over it from a fan (or the wind) so that it dries as much as possible before entering the kiln. Again, this is just to halt germination before the grain enters the kiln. Also, drying it somewhat at a cool temperature precludes any flavors that are created when wetter grain is warmed in a kiln. (However, high moisture content during kilning is necessary for some malt styles!)
5: Kilning
The kilning process is the most equipment-heavy part of malting. All of the other steps just require containers and surfaces, but some device to dry your grain until it's cracker-dehydrated is essential. The action of your kiln must comprise two parts to accomplish this: heating and blowing. The hard part is that the full range of a malt kiln's temperature should ideally be between 100F and 240F. Most standard appliances are problematic as ovens don't go far below 200F, while most food dehydrators only operate in the 120F-180F range and aren't always adjustable.
Generally, the malt should begin kilning at a low temperature (100F-120F). The temperature should then be raised slowly as the malt dries, depending on the type of malt, for example Pilsner malts finishes at around 180F, while an ale malt is usually in the 200-215F range. I have read specialty malts can go up to 270F. That being said, the kilning temperature alone will not determine the malt's final character. Each of these different malts requires individual treatment with regard to modification, withering/couching, and moisture content during kilning.
Also, it is worth noting that the higher final temperatures destroy enzymes, and will decrease the diastatic power of the malt. Mercifully, due to the relatively low water activity of wet grain (compared to wort in a mash tun), it is actually pretty hard to destroy the enzymes in your malt when working in the 100-200F range, as long as there's good air circulation. Is it possible to destroy them? Yes, and mistreatment of your grain certainly erodes the enzymatic potential. That being said, I never made a batch of malt that couldn't fully convert itself its own starches, even when I thought I had.
I originally started out using a small cabinet food dehydrator that had a controllable 120F-180F range, as dictated by its water heater thermostat. I built a box that slid in in place of shelves. Because the temperature range was low, I had to use an oven for the higher temperatures after my malt was already mostly dry, for the sake of flavor formation. This step, the final stage of highest heat exposure, is sometimes referred to as 'curing', and does not require so much air circulation so long as the malt is dry when curing begins.
My trusty dehydrator, veteran of many batches.
Trays of malt curing in the oven
Pictured below is the malt kiln I built last winter, in some of the phases of construction and use. The main structure of the kiln is a 55-gallon drum, the bottom of which I perforated with a hammer and 4” nail. I also cut a service door into the lower barrel, two inches above the bottom attached with hinges and a latch. Mounted below it are: a heat sensor (thermocouple), the heating element from a stove, and a large fan. The thermocouple and heating element are connected to a PID temperature controller, and the fan is a connected to a dimmer switch. I then enclosed the below-barrel assembly (with a wooden service door), and mounted the entire kiln on wooden legs.
A close-up of the fan and heating element
Perforated bottom, complete with creepy eye design
Fully built
Altogether, including hardware and new lumber, it probably cost around $120, but could be made for less using scavenged material. Wiring the PID temperature controller was the hardest part, but I managed it with the help of this video by “Inkbird Smart Home”:
The PID temperature controller
My kiln, overall, works well for batches of 100-150lbs (finished dry weight) of grain at once. The barrel could hold more, but air circulation inside of it when full of malt is too poor to dry more than that at once, even with several vent-tubes in place in the grain bed to help air flow. Fully drying the malt, especially at higher temperatures, requires fairly frequent turning. My experience of this could partly be because of the high humidity of my shed in winter, and it is possible that in a dry summer or perhaps with a built-in dehumidifier it would be possible to dry grain more effectively with this kiln design. In the future I would consider building a kiln more like an insulated closet with racks.
6: Removing the radicles (roots)
This step is another that rarely gets mentioned in malting texts, but is highly important for having finished malt! It is also, in my opinion, the most labor-intensive phase for the home-maltster. Like the other stages, though, it is hardly prohibitive on a small scale, so long as the malt is completely dry. I forcefully agitated the dry malt to loosen the now-crispy rootlets, then used a sturdy mesh colander to sift it all by hand. Warning: much dust.
There are ways this process can be automated, but I haven't experimented with them yet!
Sifting out the radicles, malt going from bin to bag
Whoo! After this the malt is finished and can be used for brewing, although it's best to let it rest for a few days, as the flavor will mature during this time.

Roasting Your Homemade Malt

Roasting malted or unmalted barley at home is a fairly difficult task without the right equipment, and that equipment is a coffee roaster. Otherwise, I have experimented with three methods: stove-top, oven, and fire. When using a stove-top I attempted to simulate the action of a stove-top coffee roaster by making sure the malt was continually agitated in a lidded pot, somewhat like making popcorn. I once made a nice, lightly-toasted, biscuity malt this way, but the other times I made a bitter, unusable mess and nearly ruined the pot(s).
I was equally foiled in attempting to use an oven's bake function. Although the oven worked well for curing malt in the 200F range, trying to get toasty flavors or a black malt from baking never worked. The resulting flavor was only ever the flavor of Grape Nuts cereal. As this was the easiest and most self-evident way to try to make a toasted malt, I tried many temperatures and timing schedules and only ever made Grape Nuts. This is important: the flavor transition from malty to Grape-Nutsy occurs in a very narrow window of exposure to higher temperatures. Baking one's base malt at 250F does not a Munich malt make!
My best repeatable attempts at making a roasted barley for stout came from using an oven's broiler function, removing the malt frequently to stir. The downside is that, like in coffee roasting, roasting a darker malt creates a large amount of acrid smoke. Do not do this in your house!! It will get you in trouble with whomever you share a domicile. If you live alone, you'll just smell weird for a long time and there will be no-one to tell you about it. The smoke will also coat and stain the inside of your oven. That being said, I successfully roasted 3-4lbs at a time in a pan (a second-hand oven for the garage is much cheaper than a comparably-sized coffee roaster, although the latter will allow for greater precision, and its roasting drum is better for crystal malts).
Roasting on a fire is pleasant, and it produces very dry malt. Its primary downside is that your malt will taste at least a little smoky. A low, clean-burning bed of coals will do a fine job, though, and will greatly limit the malt's smokiness. I both cured base malts and produced roasted malts using a fire pit. A thin steel sheet from the yard worked well to hold the malt over the coals. Base malt can be cured in a 2-3 inch layer with a very low fire and frequent turning over several hours. Roasted malts require a thinner layer, higher temperatures, and constant stirring.
(Once, I forgot a batch of curing base malt that was on the sheet over the fire. When I came back the bottom layer had roasted black, going up through the spectrum of browns to the top couple of inches of perfect base malt. I brewed it all into a single batch, and it made a fine porter!)
Old brick structures make good fire-pits

Storage and Hygiene

Once you begin malting, you will notice that germinating grain is a good food for many things: fungus, rodents, yeast, humans, etc. Unlike dry grain, which can be protected by a bag or closed container, malt in process will be relatively susceptible to these barley predators. A small-scale maltster (less than 30lbs/batch) simply needs to keep their germinating malt in a clean part of the house, as opposed to in the brewing garage. Wiping down surfaces between uses should be adequate for keeping them clean. It should also be noted that viable grain, even when dry and dormant, still breathes and should not be kept in a completely closed container.
A maltster making larger batches, however, will face magnified versions of the same challenges. The germinating room should have all of its cracks and crevices sealed off to prevent the intrusion of mice, bugs, and outside fungus spores. The corners and edges of the walls should be kept visually exposed and clean, and the door when closed should only have a small gap at the bottom. As many of the room's surfaces as possible should be non-permeable, or at least easily cleanable. Importantly, the germination bed/tray/floor MUST be non-permeable (I use a tarp to cover the floor). All surfaces that come in contact with the grain should be sanitized and left to dry thoroughly between batches.
The malting space must be kept clean and closed
The heat, moisture and structure of the germinating grain is perfect for molds, and the difficulty of moderating these factors is amplified when working with a larger batch of grain. A thinly-layered small batch (<30lbs) will generally receive enough air flow to prevent mold by virtue of its size, and won't heat up as much either. A larger batch however, if even a single turning of the bed is missed, can generate enough heat and moisture for a significant mold bloom to occur even overnight. If the mold is not identified and removed immediately, the process of turning the grain will spread the mold to the whole batch and ruin it. After a mold bloom occurs and the offending grain removed, all surfaces should be disinfected before reuse. If the surfaces are not disinfected, the mature fungus living in them will spread to your next batch even faster!

Conclusion on Home Malting (And a note on specialty malts)

So in the end, was the home-brew literature correct? Is small-scale malting outdated, tedious, and labor-intensive? Was it worth it? Why?
I was surprised, when I began, at how easy it could be to turn raw grain into respectable beer. For the backyard brewer, a simple set-up, small batches and a good source of barley can keep you supplied with base malt with only a modest addition to your regular brew-labor. That being said, as the scale increased, so did the labor and amount of care required: yet it never became tedious. I found many of the allegations against home-malting false, and the act of it entirely worthwhile.
The flavor of beer begins in the malt, starting with the smell of the raw barley when you first meet it. Almost every aspect of the malting process can affect that flavor while it is changing. The maltster begins making the flavor of the beer during the germination process, and has to choose along every step of the way how they are going to shape the starches and sugars, in congress with how it is to be mashed, and what kind of beer is to be made. Many of the traits that commercial base malts have today are dictated not by what is best for malt, but what is best for the techniques of mass-production; reliance on malts made only this way produces a certain sameness in our beer.
This brings me to specialty malt. Another surprise is how difficult it has been to reproduce many specialty malts—Munich malt, for instance, still escapes me. This is why I offer no specific instructions on how to make it, or any others. Malting, if anything, increases one's appreciation for the widespread availability of high-quality specialty malts (I can only hope that one day I will hone a facsimile of Gambrinus' Honey Malt). The flip side of this recognition is that a home-maltster may create malts that are, compared to the current market, completely unique.
Overall, there is a lot to be explored in the world of home-malting. Over the last year and half, I only just began to touch on some of the intricacies that I read about at the start of the adventure. Malting is a skill which, like brewing, takes (and will take me) years to perfect. I hope, though, that what I have learned so far might help someone else to find their beer's beginning!
Excellent article! I currently don't have the time or ambition you have to make my own but I wont ever rule it out. My father in-law raises a few thousand acres of 6 row for Rahr in north Dakota so I have access to some good grains. Some day, when the kids are grown and gone...
I admire your adventure but that looks like a ton of work to save $16 for a 50 lb bag of malt, especially considering I only brew around 30 gallons of beer every year.
excellent article. Your desire to experiment really embodies what home brewing is all about. If home brewing was only about saving money, none of us would do it. Keep it up....and keep writing about it. I've been looking at experimenting myself. Good luck.
Great article especially the drum for drying. I built a screen covered rotating drum in a brick oven that takes about 30 Kgs. Great thing here is that when dry the roots break away and fall through the screen so the malt is clean. Some great ideas in your article.
great article and thanks for the information!!! I have 10 acres of thoroughbred 6 row planted for a cover crop on my farm and was thinking of trying to malt some for my homebrew hobbie... I was thinking of making some sort of tumbling drum out of a food grade barrel with heat and air for both stopping germ and kilning...running air only for germ stop and adding heat for kilning....does that seem reasonable or am I missing something....
HI, could anyone help me find the word for the tool in the middle of this symbol ? I mean the two "knives" in the middle. Historically, they were used in the malting process during kilning to spread malt evenly, and perhaps for other things too. Any suggestions? Thanks.