Lesson 4 - Milling Principles
This lesson explains the objectives of milling and how mills are designed to achieve them. It details how malt is conditioned for dry milling and how we analyse grist particle size profiles. Finally, it explains how milling affects downstream brewing processes.
Preface
Milling is the process of making large things smaller by breaking them up. As brewers, we are not the only people who mill, and in fact, for some it is their profession. If you need persuading about the importance of milling, picture the nightmare scenario of lots of grains floating in our mashing vessel, providing no extract! That is the consequence of no milling.
The term grinding is often used to describe milling and ‘ground malt’ is used to describe grist. Grinding has become a term associated with milling because, historically, cereals were ground between two rough stones to produce flour. While this is accurate for underwater disc mills and fairly accurate for roller mills, we cannot describe the action of hammer mills as grinding. The accurate term for what we do when we mill is comminution which means a reduction in particle size. In this lesson we will discover the process used to comminute malt grains into grist, what needs to be achieved, and why.
Let’s stop ‘milling around’ and get on with the lesson!