Crushing Grains for Beginners

Whether it is grains, hops or adjuncts used in brewing, the freshness of your ingredients makes a huge difference. When it comes to grains, you can order them pre-crushed, but if you want the freshest taste, and can spare some cash to buy a grain mill or build one yourself, crushing your own grains is the way to go. Oils in the grains begin to oxidize and the grains absorb moisture from the air immediately after they are crushed. The best way to avoid those negative qualities is to hold off until brew day before crushing your grains (or the day before if you want to save time on brew day).

If you don’t have a mill, you can always bring your grains to be crushed at your local homebrew shop, often free of charge. This can save you money, cleanup, and space if your brewing headquarters are already tight without a mill. However, if you want to do it in the convenience of your own home, there is a right way and a wrong way to crush grains.

The purpose of crushing your grains, whether brewing an all-grain batch or just crushing specialty grains for an extract recipe, is to crack the outer husk so you can process and extract what is inside; the embryo, and the endosperm.

When all-grain brewing, the greatest impact on your conversion efficiency is going to come from how your grains are crushed — the finer the crush, the greater the extraction of the starch. The goal is to split the husk into a few pieces to expose the starch and enzymes that live beneath the husk. The broken husks will act as a filter bed when brewing all-grain to allow for an even, problem-free sparge. Make sure not to over-crush the grains — turning the barley into flour is not the goal and will turn your sparge into a paste or gum-like substance (think adding water to flour) and result in a stuck sparge. Over-crushing, while resulting in a higher yield, will also extract tannins from the husks, which will add unwanted astringency and harsh flavors to your homebrew. You need to find a balance between the desire for higher efficiency and the difficulty you will face in the sparge. The method in which you brew will make a difference in your crush: If you employ
the brew-in-a-bag method, or are just crushing specialty grains for your extract batch, you can go on the finer side of the crush as you don’t have to worry about a stuck sparge, but you still want to avoid destroying the husks so you don’t get all the tannins.

Finding the right setting of your mill to achieve that balance will take some trial and error at the beginning to determine the space between the rollers and the ideal speed to crush. Roller spacing will depend on the grain you are milling too. Specialty grains are often smaller kernels than base malts, so to compensate you will need to tighten the mill for these smaller husks. Running a handful of grain through the mill as a trial and inspecting the results will give you a good idea of whether adjustments need to be made to your roller spacing or milling technique.

Unhulled grains, such as wheat or rye, can be problematic even if you are careful not to overcrush them. With recipes that call for a high percent of unhulled grains (anything over 60%), you can use rice hulls (at a rate of about 5 per-cent of the malt bill) to act as a filter bed and help avoid a stuck sparge. Used in the same way, rice can also come to the rescue if you do accidentally overcrush your grains.

A perfect crush is the first step to a perfect beer. And isn’t that what we’re all aiming for?

Issue: September 2014