Lesson 7 - Wort Separation Process Control SAQ
This lesson provides the opportunity for you to test yourself on the material covered in Lesson 6 on ‘Wort Separation Process Control’. It will allow you to determine the level to which you have attained the learning outcomes.
Suggested Response - Q9
**In response to low extract efficiency from your lauter tun, a spent grain analysis reveals that soluble extract is 5% w/w and total extract is 6% w/w. Decide and explain which investigations you would undertake to resolve this problem.
Response:
Spent grain soluble extract will be less than 4% w/w if sparging is efficient. In this case it is not, and likely last runnings wort gravity will be higher than normal. The total extract value is satisfactory, so an investigation into conversion efficiency is not warranted.
We need to ensure that there is no preferential flow of sparge water within the grain bed. The same amount of sparge needs to flow through every part of the grain bed.
The grain bed needs to be inspected as it becomes exposed towards the end of sparged worts collection. The grain bed must be level, and have no cracks evident.
If the grain bed is uneven, there is less contact time with the sparge water flowing through the shallower parts of the bed. If the bed is cracked, then sparge water will flow preferentially through this route, and less sparge water is available to other areas of the bed.
If the grain bed is satisfactory, and there is no obvious preferential flow of sparge water, then we need to look for restricted flow beneath the false floor. The true floor has multiple outlets. If one or more of these are blocked or restricted then the area of the bed above any affected outlet will process less sparge water. Similarly, if there is an issue with one or more of the under-floor cleaning nozzles, there can be areas beneath the false floor silted up with fines and dough. Therefore sparge is restricted through that area of the bed.
To check for this restricted sparge flow, you must lift the false floor plates. This will reveal if the underplate void has any silted areas, any plate slots that are blocked, and any outlet ports that are blocked. Any faulty cleaning nozzles can be rectified at the same time.
All the above should remedy the ineffective sparging. Last runnings gravity should return to SG 1.004-1.006. Spent grain soluble extract should return to less than 4% w/w. Extract efficiency should return to greater than 98%.