Beer in glass

Advanced Brewing: Milling Grain

Ready to take your homebrews to the next level? If you’ve already started moving away from extract brewing into the all-grain territory, you might be ready to test the waters of milling grain. Milling your own grain is a great way to get consistent results and finely tailored ingredients for your brew. The process also allows you to control the size of each grain particle, which can lead to better head retention, a richer flavor, and a deeper color in your beer. 

The Basic Concept of Milling Grain

When milling grain, you want to remove the husk but not damage it. Think of the husk-like wrapping paper and the starchy grain like the present. You want to expose the starch bodies within so the enzymes in the mashing process can turn the starch into fermentable sugars (i.e. delicious beer). 

However, tearing the husks can release bad-tasting tannins that affect the quality of your beer. When milling, you want the grain to be unwrapped by your tactful aunt who carefully unseals the tape and refolds the near-perfect paper. Poorly milled grain will look like a toddler tore through the presents with wrapping scraps everywhere. Additionally, keeping the husks intact has a practical benefit for the homebrewer. During the mashing process, the husks actually help filter the grains so the mash doesn’t clog up as easily.

Reasons for Milling Grain

In general, milling your own grain allows the brewer more control over the final product: the beer. Chances are, the reason you got into homebrewing is to brew exactly the beer you like. So any technique to have a bit more precision over the final product should seem rather appealing! 

Control the Size of the Grist

To achieve this extra “oomph” in quality, milling grain allows you to control grist size. Depending on your grain type and brewing method, you likely want different grist sizes. For example, for a “brew in a bag” method, you can grind the barley much finer than a standard brewing in a mash/lauter tun. Secondly, different grain types require different milling sizes to fully expose the starch. You can adjust the grist size by changing the “gap size” of your mill. More on that later.

Longer Shelf Life

Another perk of milling grain is that whole grains have a longer shelf life than milled grain. Milling your own grain not only allows you to stock up on whole-grain barley and make fewer trips to the store, but the process also lets you take advantage of the discounted prices of bulk purchasing. Milling grain saves you time and money!

Grain Milling Equipment

The basic grain mills all use a series of closely spaced rollers to crush grains. Some grain mills are electric while others are powered by hand. Your malt and grain can be loaded in and then just set on the table or over a bucket. At the homebrewing scale, all-grain mills have a similar setup. The basic parts include a hopper, the rollers, and the crank. 

The Hopper

The hopper is the top reservoir that holds the whole grain. You can purchase mills with different size hoppers. These options allow you to grind more or less grain at a time, so it really just depends on your preferences for homebrewing. Most homebrew mills have hoppers capacities that hold between 5-15lbs of grain.

The Rollers

The rollers are the part of the grain mill that actually crushes the grain. Most mills come with two or three rollers. Three-roller mills tend to be more expensive, but are generally more efficient and better at removing the husk. However, running your grain through a two-roller mill twice will produce the same effects as a three-roller. 

The surface texture of the rollers can also differ. Most rollers have a “knurled” surface which appears like lots of tiny bumps. Some rollers may be “fluted” instead. Fluted rollers are less likely to tear the husk of the grain, but are much harder to manufacture. Because of this, mills with knurled rollers are both more common and more affordable. 

Gap Size

When milling your own grain, you want each grain cracked enough to expose the starch bodies. However, you don’t want to completely pulverize it! By adjusting the gap size between the rollers, you can control your grist size. Large-scale breweries have the equipment (like proper filters) to handle finer particles, but a typical homebrew system with a mash tun and hot liquor tun needs a coarser grind. To achieve this, use the credit card trick for your rollers!

The Credit Card Trick

A credit card can help you adjust your mill rollers to standard gap size. Gently tighten the rollers evenly around a credit card. The card should fit snugly but be pulled free without damaging the plastic. (Use two cards simultaneously for a three-roller mill.)

Grain Storage & Brewing

Now that you’ve got your home grain mill set up, you are well on your way to becoming an excellent all-grain brewer. If you’re not ready to brew immediately, both your whole grain and milled grain keep best when stored in a cool, dry place (between 50-80°F). Storing grains adds to the (already lengthy) list of the benefits of an at-home cooler system. Check out CoolBot’s systems to create a DIY walk-in cooler. Homebrewers use this technology to create a regulated space for fermentation, chilling brews, and grain storage. If you are jumping straight into brewing, happy fermentation!

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