The Ultimate Guide to Grain Crush Size for BrewZilla Brewing

 

In order to ensure complete control over your recipe, efficiency and brewing system, you really need to be crushing your own malted grains. After several years of brewing on our 35L BrewZilla 3.1.1 using pre-milled grains from our local home brew shop, we decided to invest in a grain mill and begin crushing our own grains for each recipe and brew day. This lead us to the question as to what the ideal crush size is to use on a BrewZilla system?

Impact of Grain Crush Size

Grain crush size plays a crucial role in the brewing process. Crush is typically measured as being "fine" or "coarse" with each providing pros and cons to the end result. We'll break down some of the impacts the crush size can have below;

Efficiency

Finer crush sizes increase the surface area of the grain, allowing for better extraction of fermentable sugars during mashing. This can lead to higher efficiency and more alcohol content in the final product.

Mash Performance

Coarser crush sizes help prevent stuck sparges by maintaining better flow through the grain bed. This is particularly important in systems like the BrewZilla that use a recirculation or lautering system. Conversely, a finer crush will slow down recirculation speed, and can lead to a mash or sparge becoming "stuck" where the water ceases to flow through the grain bed.

Flavor and Clarity

A finer crush can sometimes lead to increased tannin extraction from the husks, which might cause astringency in the beer. It can also result in a cloudier final product if not properly managed. Keeping the grain husks mostly in tact allows them to better filter the recirculating wort as well which can help improve the clarity of the wort at the end of the mash.

Consistency 

Achieving a consistent crush size helps ensure repeatable results from batch to batch, which is essential for maintaining the quality and characteristics of your brew

In terms of milling grains, a finer crush is achieved by setting the grain mill gap lower or smaller, so the rollers are closer together. A coarser crush is achieved by the opposite - setting the gap between the rollers further apart.

Grain Milling Guide

The below grain milling guide from our friends at Hoppy Days Brewing Supplies gives some great information on what their recommended grain mill gap sizes are for different maltsters and brewing systems.

The table is fairly self explanatory - look for the brand of malt you're using in either the Coarse or Fine column then look at the corresponding mm value in the middle.

For example, if we wanted a coarse crush when using Simpsons malt, we'd start with a recommended gap of 1.30mm. Conversely, if we wanted a fine crush for Gladfield Rye malt, we'd start at 0.50mm.

Recommended Crush Size for BrewZilla

If you're using a BrewZilla (or a similar all-in-one brewing system), you're going to want a crush size that is coarse. Prior to our first attempt at crushing our own grains, we reached out to Gavin from The Homebrew Network - an absolute veteran of homebrewing, in particular with the BrewZilla, and he said he typically uses a mill gap size of 1.35mm for most grains when using a BrewZilla, so this was our starting point.

Unsurprisingly, this turned out to be pretty good advice, as we hit our target efficiencies almost spot on (1 point higher) on our first attempt from the Brewfather calculated 75% brewhouse efficiency for the BrewZilla. So this would be a great starting point for anyone looking to mill their own grains using a BrewZilla. You can see in the picture above what the crush looked like - most of the grain husks still intact (but cracked). This was Barrett Burston ale malt.

Check out the related articles links below for more articles on milling your own grain!

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