Milling your Grain:
It may not seem like it’s necessary to note, however, size does matter when it comes to your grain and how it is milled. There is a difference between milled and unmilled grain and will, therefore, make a difference to your beer.
Once the Barely has been malted, it becomes brittle and rather dry and will therefore determine whether the grain is cracked. This term is typically referred to as the friability of the malt and has to do with the moisture within the kernel itself and its ability to be cracked or not. Malt that is too moist will not crack open and will get squashed in between the rollers which will give a less yield extract.
Note that when we mill our grain, we do not want to turn our grains into a fine powder either. However, we do want to get the grains to crack and allow the brewing liquor access to do the necessary conversions of the starchy materials into the desired fermentable sugars. It is ideal that each malt kernel is cracked into 3-6 individual pieces whilst leaving the husk intact. Not only do they expose the internal part of the grain for extraction purposes – they utilize the husks to form as a filtering bed. However, because they contain tannin and other various bitter compounds, it is not desired to extract them as they will give your brew some undesired flavours. One way to prevent this is to make sure that the husk is not shredded. These harsh flavours may also be extracted at a low pH as an alternative.