How To Malt At Home: An In-Depth Guide

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How to Malt at Home

An In-Depth Guide

Written by Mark and Christopher || 02/23/17

Malting at home is often perceived as hard and not worthwhile – and from our understanding it’s because of 4 perceptions:

  1. Malt is cheap! Why bother making it?
  2. Homemade malt is inferior!
  3. There isn’t a lot of great information out there on how to do it. Malting is a bit of a mystery, and, at the moment, it takes effort to uncover the secrets.
  4. Instead of a 4 hour brewday, it’s a weeklong project. You need to check on the grain a few times a day, and this can be too much work.

Fair points, but we can poke holes in all of them:

  1. Why bother making beer? It’s cheap too! We brew beer because it brings us joy, not for the cost savings. We make our own malt for the same reason.
  2. You can make good malt at home, in the same way you can make good beer, you just need to have a good method and the proper setup.
  3. Malting’s mysteriousness is an opportunity for exploration. It offers new possibilities in the brewhouse like the flavors of heritage grain varieties grown by a local farmer, new malt styles unavailable commercially, or historical, undermodified malts. The more of us exploring, the more we’ll discover!
  4. The time commitment can be a challenge, but careful planning can make it easier. One of the reasons we’re making automated equipment is to address this. If this is the first time you’ve heard about our malting equipment, you can read more here, or poke around our website.

Like everyone else, we started malting in buckets, and our drive to make better malt has led to the creation of our automated malting equipment. We’ve built this equipment to deliver new levels of control, increased consistency and quality, and decreased labor.

But this post is not about our equipment as it is now – it’s about where our malting began. As home brewers know, you have to start somewhere. In the hopes of inspiring more people to chit a batch of barley, watch the acrospires grow, and help forge the path up the supply chain, we’ve put together a guide on malting at home with whatever equipment you already have lying around.

How to Malt at Home

Malting is comprised of 4 steps and takes, on average, 7-10 days:

  1. Prep/Washing – 30 minutes
  2. Steeping/Air Resting – 2 days
  3. Germinating – 4 days
  4. Kilning – 1 day

We’ll walk you through all of these steps, and try to clarify existing misconceptions. Most guides we’ve seen are too vague, or are restatements of incorrect or not-fully-true advice. We’d recommend taking most information you find on forums or blogs with a grain of salt. The only really solid information on home malting we know of online is our friend at Brewing Beer the Hard Way. His content is superb, and a great demonstration of the opportunities to explore malt and beer.

This guide is a consolidation of our experiences malting at home, best practices from the malting literature, and other common wisdom held by the malting community. It’s relatively in depth and might feel overwhelming at first, but think of how you felt starting out with brewing! There’s a lot to learn, but once you start doing it you’ll pick it up quickly. You’re just sprouting seeds after all!

Equipment

To start, here’s an idea of what type of equipment you need:

Malting Step Barebones Equipment Additional Equipment
Washing Bucket, water source, strainer Bucket with drain valve
Steeping Bucket, ~55F water source, 50-60F ambient conditions, teaball or mesh bag Climate controlled space – temp (55F) and humidity (95%+)
Air Resting Bucket, 50-60F ambient conditions, teaball or mesh bag Bucket with drain valve, climate controlled space
Germination Plastic container, 50-60F ambient conditions, spray bottle, teaball or mesh bag Climate controlled space
Kilning Oven, thermometer, teaball or mesh bag, sieve Dehydrator


In addition, you need grain! We’ll be focusing on hulled malting barley (2-row or 6-row) in this guide, but boy is there space to explore and roam with other grains. You can get good barley from a seed company (we list some good options
here). If this isn’t possible, the less ideal source is feed barley from a farm store. You also might find some at a natural foods store or food co-op.

Prep

  1. Weigh out your barley in a large bucket.
    • Your final malt weight will be 80% of your starting barley weight. If you want 4 lbs of malt, start with 5 lbs of barley. Some of this weight loss is water. Barley has a moisture content of 12% while malt is just 4% water.
  2. Set aside a small grain sample to track moisture and record the sample weight. The moisture content of your barley kernels is a major indicator of your progress during malting. It tells you when you’re done steeping and when your malt is finished. To track moisture, you’ll need to weigh your sample periodically and the weight change will tell you your new moisture content. There’s a simple equation that we’ll take you through later.
    • We put a 5 g sample in a standard tea ball. Other maltsters use mesh bags and larger samples. What’s important is that the sample is exposed to the same moisture and temperature as the rest of the grain, and that the sample kernels can not escape.

Washing

When you buy clean grain, it has been through a seed cleaner. Even so, it’s still fairly dirty, as it’s coated in dust from the field. By washing grain, you’re getting most of the dirt off and skimming off unviable seeds (“thins”) and any chaff that got through the seed cleaner. Malting doesn’t require the same level of painstaking sanitation as brewing, but this is a crucial step to keep your grain from being a hospitable environment for microbes.

  1. Fill your grain bucket with warm water until there is 4” of water above the level of the grain.
    • Warm water does a better job of rinsing the dirt off the grain than cold water. Plus your stirring arm will appreciate it.
  2.  Stir the grain vigorously. Thins will rise to the surface of the water and viable grain will sink back down. Make sure you rouse the grain from the bottom of the bucket to separate out all of the thins.
  3. Skim the thins off the water’s surface with a strainer then continue rousing and skimming until just a few kernels rise to the water’s surface.
  4. At this point, you will be appalled at how filthy the water has gotten. Pour off this dirty water and refill the bucket with clean water. Try not to lose any grain in the process.

    Dirty

    Clean

  5. Repeat the stirring, draining, and refilling steps until the water is fairly clear. It doesn’t have to be crystal clear, just clear enough that you can make out the individual grain kernels through the 4” of water. We find that this usually happens on the 3rd fill.

Water after cleaning from the first, second, and third fillings, left to right

Steep

Steeping is when the malting process begins in earnest. The purpose of the steep is to hydrate the grain to the point at which it germinates. Think of spring rains, soaking the soil and wetting all the seeds that have been lying dormant for months. Steeping is an awakening. This water is the lubricant that gets things moving inside the kernel (for a deeper look at this, check out our article on enzymatic activity inside the seed).

Modern maltsters typically aerate their grain in the middle of the steep phase by draining the steep water to give the grain access to oxygen. When they refill the steep tank, the grain takes up water faster than before. The goal is to get the moisture content to 45% before moving onto the germination phase. Typically this takes us 3 steep cycles, but it can range from 2-4.

  1. Fill your grain bucket with cold water until there is 1” above the level of the grain. This water should be as close to 55 F as possible.
  2. Put your bucket into a temp controlled space that will maintain 55 F.
    • The best you can do here is to put it in a fridge or insulated structure that can be set to 55 F with a temp controller. Insert the temp sensor into the middle of the grain bed.
    • If you don’t have a temp controlled fridge, a cool basement will do. The ideal range of steep temps is between 50-60 F. At higher temperatures, you get more uneven water uptake, which can lead to inconsistent germination later on. That being said, if your steep water gets up to 65 F, your malt will not be ruined.
  3.  After a period of steeping, drain the water and return the grain bucket to your temp controlled space for an air rest. Reinsert the temp probe if you have one.
  4. After a period of air resting, repeat the steep cycle and refill the bucket with cold water.
    • The standard steep schedule is to alternate between 8 hours of steep and 8 hours of air rest until the grain hits 45%. This can be hard to maintain with a full-time work schedule. You should feel free to adjust the steep schedule to your schedule. We often steep for 8 hours and air rest for 12-16 hours. As long as you get your grain to 45% moisture, you’re golden.
  5.  If you’re a little bit under target moisture, feel free to spray the grain then mix it around to bump its moisture up a few percentage points.
    • Using grain at a higher moisture content results in more vigorous, and faster, germination. Temp control and frequent turning become even more important in this situation. When starting out, it may be a better idea to start germination at a lower moisture content, around 42%.

Chit Counts

If you are doing air rests, the grain will start to ‘chit’ at some point during the steeping phase. The timing depends on your grain and your steeping times and temps, but we’ve seen the first chits as early as the end of the first air rest. It’s a good practice to do chit counts to track your grain’s progress and assess your grain quality. Modern malting barleys ideally have a chit rate of 99%.

  • The chit is the first sign of the emerging rootlets. You will see something white poking out of one end of the kernel. When we do a chit count, we check 50 kernels for this white protrusion, then multiply that number by 2 to get the chitting rate.

Measuring Moisture Content

Throughout steeping, but especially near the end, you should be tracking your moisture content. We take readings when we transition between steeps and air rests.

  • To ensure accuracy, you need to get rid of any surface moisture from your grain. We actually empty our tea ball and pat the kernels dry with a dish towel until no more wet spots show up on the towel. Then we weigh the grain. When refilling the tea ball, we’re very careful not to leave any kernels behind, even broken kernels or other debris. If it went into the tea ball initially, it stays in the tea ball.
    • If you’re using a mesh bag, you may not need to take the grains out of the bag. Make sure you shake off most of the moisture then pat the bag/grains dry with a towel and weigh it.
  • Surprisingly, the moisture content usually rises during air rests. After draining the steep, there is a surface moisture on the grain which it takes up throughout an air rest. By the end of air rest, the grain’s surface is usually no longer wet to the touch.
  • If you weighed your sample at the end of a steep, make sure you re-wet it so that it too can soak up surface moisture during air rest.
  • Calculate your current moisture content with your current sample weight. This is middle school math, so don’t complain. Here is the equation:

Current moisture % = 100 – (100 – starting moisture %) / (current weight / starting weight)

  • Let’s do an example together. You can assume the starting moisture content is 12%, as that is the safe level for long-term barley storage. The starting weight was 5 g and our current weight is 8 g.

Current moisture % = 100 – (100 – 12) / (8 / 5) = 45%

Perfect. We’re ready for germination!

Germination

The grain will physically change during germination. Rootlets will push out of the husk and lengthen. The grains first shoot, called the acrospire, will lengthen and grow inside the husk. The kernel will become easier to roll between your fingers. These are all the classic signs of modification. Steeping started the enzymatic processes necessary to make starch available in the grain’s energy reserves, called the endosperm, and it’s now prime time for the enzymes.

The maltster’s job during germination is to mix/turn the grain and track modification. Turning detangles rootlets prone to grow into clumps and disperses heat and CO2 produced by the grain’s respiration. Modification is tracked in order to know when it’s time to kiln.

  1. Move your grain from your steeping bucket to a germination vessel.
    • Ideally, this is a larger container where you can spread the grain out and maintain a thin depth of 1 – 4 inches, instead of the deeper pile in a bucket. It’s easier to control the temperature of a thinner grain bed. A thicker grain bed is possible, you’ll just be turning it more often.
  2.  Turn your grain several times a day.
    • You can set certain times to turn the grain, but also realize that this a natural process that does not conform to neat schedules. We turned our grain 2-4 times a day for this batch. Brewing Beer the Hard Way turns his 4 times a day.
    • Respiration is increasing as germination progresses, resulting in increased heat output. Thus, the grain may need to be turned more between days 3-5.
  3.  Spray your grain lightly before turning if there is excessive drying.
    • Unless the space is humidified, the top layer of grain will likely dry out between turnings. This is okay, but not ideal. If the entire grain bed is drying out, a spray may be in order.
  4.  When you check on the grain, use your senses to make sure things are going smoothly.
    • If germination is going well, you’ll smell cucumbers or fresh cut grass; if it’s not going well, the smell may be more moldy or rotten. Mold or rotting can happen when the temperature is too high and the grain is moist, or if you have too many broken kernels in the batch.
    • The rootlets will be bright white and crisp at first, but some will likely turn yellow or brown as growth progresses, especially if the grain gets too dry.

Tracking Modification During Germination

There are a few ways to track the degree of modification. Big or small, the professionals don’t have better in-process control tests than you do in your basement. It’s all about feeling, looking, and smelling.

  • Track the growth of the acrospire as it grows along the edge of the grain. Hold a kernel vertically between your thumbs, with the smooth side facing you. Use your fingernails to split the outer layer open, exposing the acrospire just inside. This will take some practice to learn how to orient the kernel, and how much force to use.

1/2x Acrospire

<3/4x Acrospire

 

>3/4x Acrospire

Almost 1x Acrospire

  • Similar to counting the chitting rate, count the acrospire growth by analyzing 50 kernels. You can do this roughly once a day, but it is more important towards the end of germination.
  • Separate the kernels into categories based on the length of the acrospire in relation to the length of the grain. Double these results to get a percentage out of 100.
    • ¼x the length of the grain
    • ½x the length of the grain
    • ¾x the length of the grain
    • 1x the length of the grain
    • 1+x the length of the grain

  • When a majority of the kernels are between ¾ and 1x the length of the grain, it’s likely time to kiln. This takes some judgement on your own part. Don’t wait so long that there are many overgrown kernels past 1x the length, but do wait if you still have many kernels only at ½x the length.
  • When you’re performing acrospire counts, roll the kernels between your fingers. There will be edges in the beginning preventing the kernel from rolling smoothly. The kernel will become squishier as modification progresses, and rolling will be smooth when modification is complete. Think of it as rolling a triangle between your fingers, which will gradually become a circle.

    The starchy endosperm with husk removed

  • Another test to determine if modification is complete involves removing the husk from a kernel and smearing the white, starchy endosperm between your fingers. If the grain isn’t ready yet, you’ll experience a hard ball unwilling to smear. If the grain is ready, you’ll be able to fully smear the starch.

Kilning

Drying the grain down during the kilning process stops growth at the ideal moment when starch has been made available, but hasn’t been used by the plant. We added water to start the enzymatic process, and now we’ll take it away to put the enzymes on hold for the duration of malt storage. On brew day when you mash in, the enzymes will resume their work, continuing the exact same biological processes, and will be fully stopped when you mash out and denature the enzymes.

  1. Use a dehydrator or oven to dry the grain. Load the grain onto dehydrator trays, or baking trays/containers.
    • A dehydrator is a better option, as blowing air past the grain to remove moisture is more efficient than just heating the space up in an oven. If you only have an oven, prop the door open a bit, or open the door relatively frequently, to allow moist air out.
  2.  There are several stages of kilning. To start, dry your grain at 120 F for 8 hours.
    • First, you’re removing the bulk of the water. This is the free drying stage, and takes place between 45% moisture and 25% moisture. The temp should be between 112-140 F.
  3.  Raise your temp to 140-150 F for 4 hours.
    • After removing the most accessible moisture in step 1, you enter the intermediate stage. You want to ramp up the temperature to get at the moisture that’s bound up deeper inside the seed.
  4.  Cure at 170-200 F for 3 hours for most base malts.
    • When the moisture content has gotten down around 10%, it’s time for the curing stage. This high heat step adds malty flavor and gets rid of off-flavors. These kilning times and temps are generalizations, so take them with a grain of salt. Kilning schedules vary immensely based on the malt you’re trying to make. Instead of listing them all here, we’ll just direct you to this great resource on malting times and temperatures from Brewing Beer the Hard Way.
  5. Tweak existing kiln schedules to suit your setup and batch size.
    • Our dehydrator can remove moisture very quickly, so we cruise through the first two kilning steps. But the dehydrator maxes out at 165 F, so we have to use the oven for curing. We transfer the grain to ovenware, and set the oven at roughly 180 F. We leave the grain in for 3 hours, and check it every once in awhile. You can turn it occasionally, but don’t need to. The longer you leave it in, the further from a pale base malt you’ll get. The malt will develop more color and more of a malty, bready flavor.
  6. Take moisture readings throughout to determine when to ramp up temperature and when to end kilning. Use the adjusted moisture equation below.
    • The moisture ranges that define each kilning step are very loose, so don’t worry about sticking to them closely.
    • Your moisture readings during kilning will come out lower than the actual moisture content, often reading negative at the end of kilning. The reason for this is that the grains lost about 6% of their dry matter during germination (germinating grains respire and use energy reserves in a similar way to humans burning calories). You’ll need to adjust the moisture equation from above to account for this.
    • Let’s assume the same starting moisture of 12% and starting weight of 5 g, a current weight of 4.2 g, and a respiration loss of 6%.

      Adjusted moisture % = 100 – ((100 – respiration loss %) / 100) x (100 – starting moisture %) / (current weight / starting weight)

      Current moisture % = 100 – ((100 – 6) / 100) x (100 – 12) / (4.3 / 5) = 3.8%

  7. Ideally, you will end with a final moisture content of 4%.
    • As a home maltster, this number does not need to be that exact. There is no quality issue with drying it down further – you’re just wasting energy at that point. If you finish with higher than 6% moisture, you can get “slack” malt. This is a problem if you plan to store your malt for a long time. It won’t keep as well, losing aroma over time, and it will not mill as well on brew day. If you start to notice this problem in your home malt, don’t wait so long to brew with it! Fresh malt is better anyways.
    • With all that being said, we would recommend against lengthening your curing times to ensure you get to 4% moisture. Extending from 3 hours to 5 hours of curing could be the difference between a pale malt and a Vienna malt. If you’re worried about under-drying, extend the length of your intermediate kilning stage.
  8. When the grain is done, take it out and let it cool. Now there is one final step – de-culming.
  9. Culms are what rootlets are called by maltsters, so de-culming is removing the rootlets. Mix the whole batch in a bucket with your hands, rubbing the grains together and agitating them. The culms should come right off.
    • Rootlets, not acrospires, can supposedly add a bitter flavor to beer, and they absorb water during storage. We’ve never tested the flavor claim, but have followed the advice so far. The culms become very brittle during kilning and break off easily.
  10. Put the grain in a sieve, and shake it above a surface you can sweep. The rootlets will fall through, and you’ll be left with clean, delicious malt.
  11. Once you’ve cleaned the whole batch, store it in an airtight bag until you brew.
    • It is often claimed that you should store malt for 3 weeks after kilning. We haven’t seen any evidence for this, and the reasons are a bit suspect. We say go ahead and brew when you’re ready – tomorrow, or in a month! The fresher the grains are, the better they’re going to taste in our experience, especially if you choose to roast a section of your grain bill at a higher temperature.

Conclusion

So there you have it – an in depth guide to malting at home with simple equipment. There’s a lot of information up there, but there’s plenty of other tidbits that we decided not to include. If you have questions or want to fill in any gaps, use the comment section below.

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