Milling Technology SAQ

Question 1

Rank the following mills in order of their effectiveness at producing a desirable grist: Hammer mill, Six-roller conditioned dry mill, Steep conditioned mill.

Answer 1

1. Hammer mill
2. Six-roller conditioned dry mill
3. Steep conditioned mill

The hammer mill applies the most force, best for poorly friable malt, while the steep conditioned mill is the poorest performer.

Question 2

What is the primary function of a hammer mill in milling under-modified malt?

Answer 2

To effectively comminute poorly or under-modified malt to expose starch for conversion during mashing.

The hammer mill’s capability to apply force makes it suitable for this task.

Question 3

What are the three pairs of rollers in a six-roller conditioned dry mill designed to do?

Answer 3

• Break up the kernel
• Mill out the endosperm
• Comminute coarse grits

The arrangement of screens between rollers affects the operation of the mill.

Question 4

True or False: The grist produced by a six-roller conditioned dry mill is suitable for a mash tun.

Answer 4

False

The grist is too fine for a mash tun, leading to a sunken mash bed.

Question 5

What is a significant disadvantage of the steep conditioned mill?

Answer 5

It cannot apply sufficient force to break down poorly friable unmodified endosperm fragments.

This limits its effectiveness in milling under-modified malt.

Question 6

Describe the operation of a six-roller dry mill.

Answer 6

It has three sets of crushing rollers with oscillating screens that separate grist components by size.

The design allows for effective milling while limiting husk damage.

Question 7

What is one reason to select a six-roller mill?

Answer 7

• Best suited for lauter tuns
• Processes poorly modified malts
• Lower energy requirement than hammer mills

They yield greater levels of extract efficiency.

Question 8

How does a steep conditioned wet mill operate?

Answer 8

It uses a two-roller mill attached to a steeping chamber where water is sprayed onto malt before milling.

This design helps preserve the husk for better wort separation.

Question 9

What are the problems associated with a full steep wet mill?

Answer 9

• Difficult to keep clean
• Requires frequent CIP
• Highest water use and effluent generation
• Cannot mill some adjuncts
• Difficult to operate consistently

These issues limit the effectiveness and practicality of full steep wet mills.

Question 10

Fill in the blank: The steep conditioned mill can mill under-modified malt more effectively than the _______ wet mill.

Answer 10

full steep

This is due to better control of steeping time and milling speeds.

Question 11

What mill would be recommended for a small pub brewery making 3,000 hL per year using an isothermal mash tun?

Answer 11

A two-roller dry mill.

It produces grist with a particle size that remains buoyant in the mash.

Question 12

What is the best mill for a large brewery making 1,500,000 hL per year using lauter tuns in an area of water scarcity?

Answer 12

A six-roller dry mill.

It uses less water than wet mills, making it suitable for water-scarce areas.

Question 13

What type of mills are suitable for a medium-sized brewery specializing in export beer using a mash filter?

Answer 13

• Hammer mills
• Underwater disc mills
• DISPAX-REACTOR®

These mills provide better control over oxidation, which is critical for shelf-life stability.