Lesson 7 - Malt Quality SAQ
This lesson provides the opportunity for you to test yourself on the material covered in Lesson 6 (Malt Quality) and determine the level to which you have attained the expected outcomes.
Suggested Response - Q6
*Explain the parameters friability and homogeneity. Why are they important for the brewhouse?
Response:
Both these parameters refer to the level of malt modification.
They are determined using a friabilimeter. Friability is the amount of malt that has passed through the sieve. Homogeneity refers to the weight of the malt that remains after it has been sifted through a 2.2 mm slotted sieve. Further analysis of the remaining malt will classify it as PUGs (partially modified grains) and WUGs (wholly unmodified grains). A low friability result and high levels of PUGs and WUGs indicate that there is still cell wall present, suggesting incomplete modification. WUGs indicate that the kernel was dead and did not modify at all.
The intact cell wall material shows under-modification during the malting process. Starch granules are still isolated in the protein matrix and cell walls surrounding it. This will impact the brewhouse as follows:
- Inefficient milling ‒ the under-modified and unmodified areas will be harder to mill, compared to the modified endosperm. The mill gaps are designed for modified malt, thus under and unmodified grains may be more difficult to mill.
- High levels of WUGs ‒ can cause high wort viscosity, which can lead to slow lauter tun run-off.
- Extract loss ‒ the starch granules will not be adequately exposed to α- and β-amylase for conversion to fermentable sugars and dextrins.