Great Grain: Crack the Mystery of the Crush
Malted barley is the heart of all beer. Its presence is paramount to the flavor profile and character of the finished brew. Whether you are a seasoned all-grainer, a partial masher, or an extract brewer who steeps your grains, the physical condition of the grains needs to be just right to achieve the desired effect. So take a quick look at the hero of this story — the barley kernel.
What’s in There?
The barley kernel can be viewed in four very basic parts. The outermost layer, the husk, is a tough coat that surrounds the seed and helps it survive partway through the malting process (the seed is alive at the beginning of the malting process, but is killed when the kilning process begins).
The husk plays another important role in the brewing process. It helps separate the particles in the mash and sets up a filter bed that is essential for easy sparging. Without the help of the husk, it would be difficult to successfully run off the sweet wort from the grains.
Delving deeper into the barley kernel, the next layer is called the aleurone (also known as the seed coat). This thin layer secretes enzymes that are vital to mashing.
But wait, there’s more! The center of the kernel is separated into two parts, the embryo (the smaller part) and the endosperm (the larger part). The embryo can be considered the control center for germination. The endosperm is the source of food for the embryo; it contains starch and protein. These proteins give the yeasts the nutrients that they need for a healthy fermentation.
Now that you have an idea of what’s in that little kernel, you can understand why you need to have access to all of these parts to create great beer at home.
The Ideal Crush
The idea behind crushing the malt is to open up the malted barley kernel and allow you to process and extract all that you need from inside it. You want to split the husk along the length, if possible, in big pieces. The kernel should be broken into several larger pieces and some smaller pieces to expose the starch and enzymes. Your goal is to keep flour to a minimum.
In crushing, as in everything else in life, you must achieve a balance. If the crush is light and the particles are larger, the husk is undoubtedly well preserved for the runoff, but the barley kernels are not broken down enough to give a good yield. If the crush is too heavy, the husk is powdered and the particles are very small. Although the yield may be higher with a finer crush, this can lead to some harsh flavors and a great deal of trouble running off the sweet wort from the grain bed (if you can even have a bed without a husk). The bed becomes gummy when the grain is milled too fine. Clearly, some sort of compromise must be met.
The compromise crush for most homebrewers is more on the coarse side, with the least possible amount of pulverized material. Yes, this will definitely decrease the yield available from your grains. But on a homebrewing level, it makes sense to sacrifice a small loss in extract yield and add another half-dollar’s worth of grains to prevent headaches in this area. As you become more experienced with crushing the grain and the mashing process, and more familiar with your equipment, you may be able to fine-tune your crushing technique to suit your apparatus and increase your yield.
“What’s in a mill? That which we call a mill, by any other name, would crush as neat.”
—William Shakesbiere
Plate Mills
Although all mills are not the same, their purpose is: crushing the grains consistently. Thanks to the voice of homebrewers everywhere, there are a great variety of mills on the market today. These mills break down into two basic categories, the plate (or grind) variety and the rolling variety.
The first type of mill is called a plate mill and is manufactured to grind cereal grains into flour. These are usually the most affordable mills and range in price from about $37 to $50.
These mills are simple machines that push your grain, usually with a spiral auger, through the gap (or distance) between two metal plates. These plates usually have ridges or bumps on the opposing surfaces to grip the grains as one of the plates rotates against the other, creating a grinding action.
The ability to adjust the distance between these two grinding discs is absolutely essential to a good-quality crush. If the plates are too far apart, many grains will be pushed through without being crushed and will be useless for brewing. If the plates are too close, they can easily grind grains into flour, leaving only a few traces of husk behind.
With the plate-type mills it is best to create a constant speed either by hand or by means of an electric motor or drill. This gives a better and more consistent crush. A trip to the hardware store should provide all the equipment needed for a simple conversion.
With the Corona-brand grain mill, for example, all that is needed for basic drill conversion are a common bolt—to fit into the hole that holds the handle on the auger shaft—and a heavy-duty variable speed drill. The drill should fit on the head of the bolt that is in the handle end of the auger.
More complicated setups can be made using a motor-and-pulley arrangement. You will get the best crush with the right adjustment of the plates and only a couple hundred RPMs (which, by the way, is a lot faster than you can crank the mill by hand).
One of the drawbacks of plate mills is that its adjustment usually needs constant attention. Checking the output of any mill is very important, but with the plate mills, it needs to be done much more frequently. To check the output, just grab a handful of the grains exiting the mill and look them over. If you grab from the pile, you don’t always get an accurate representation, as the husks tend to migrate to the bottom of the pile.
Another problem with plate mills is capacity. For most all-grain recipes, these mills do not hold enough grain to grind efficiently. It is difficult to get that ideal crush when you have to stop many times to refill the hopper with more grain. So plan to have someone there to help top you up or make yourself a bigger hopper!
For the cost, plate mills do a good job on your grains and by grinding at home, you can preserve peak freshness.
Roller Mills
The other category of mill is the roller mill. Roller mills range in price from approximately $80 to $300 depending on quality and features. These mills use cylinder-shaped rollers to crush the grain, usually with a knurled surface to grab the grains. Some roller mills use only one roller and feed the grain between a stationary plate and the roller surface.
Other roller mills feed the grains between two rollers spaced close together. Both processes squeeze the grains just enough to crack them into little pieces and drop them through quickly, limiting contact time with the rollers. Because the grains pass quickly through the rollers and there is not a grinding action, the husks are preserved. This makes the roller mill the most desirable mill among the majority of homebrewers.
The ability to adjust the gap between the rollers is much more accurate than the plate types and can be beneficial if you find yourself brewing with many different sizes of grain. With a roller mill, adjustability is not as much of an issue as with the plate types. These mills can also be motorized to ease the homebrewer’s workload.
This is best done with a motor-and-pulley arrangement, with a large-diameter pulley on the mill and a small-diameter pulley on the motor, to step down the speed. This can be done with a direct drive motor as well, but you want a slow-speed motor if you plan to direct drive, depending on your mill, 300–500 rpm is generally the recommended maximum speed. Too much speed could cause excess wear on the mill without improved results. Hopper size can also be an issue with these roller-type mills.
Whatever mill you choose, check it out carefully before buying to be sure it will fit your needs.
