Lesson 6 - Wort Separation Process Control
This lesson deals with wort separation process control. The different methodologies of measuring and calculating extract recovery are explained and demonstrated. A methodology is explored, as is how to investigate and resolve performance issues with extract efficiency, wort quality, and cycle time.
Spent Grain Analysis
Hand evaluation will identify any whole grains (milling issues). The degree of ‘stickiness’ will indicate either the presence of unconverted starch or the sugars that have not been removed by sparging. A quick iodine test will confirm starch presence.
There are two laboratory methods used to determine the amount of extract left in spent grains. For total available extract the spent grains are dried, milled then added to water and boiled. The mash produced is cooled to 45°C and calcium chloride and saccharifying enzymes are added. The mash is then heated to 70°C at 1°C per minute and held at 70°C for 60 minutes before being cooled to room temperature. The mash is then filtered and the gravity of the filtrate is measured and the w/w extract calculated. This should be less than 7% w/w if our brewhouse milling/mashing regime has been successful.
For soluble extract in the spent grain dried milled spent grains are added to water at 70°C and the mash is held at 70°C for 60 minutes. The mash is then cooled to room temperature and filtered to remove the spent grains. The gravity of the filtrate is measured and the w/w extract calculated. If sparging has been successful, this should be less than 4% w/w.
High last runnings, gravity and high spent grain soluble extract suggest that we have ineffective wort separation. What do we need to do to resolve this?
Firstly, as at mashing, we need to be confident that we are accurately measuring our inputs and outputs.
- Sparge flow meter calibration. Are we adding the correct volume of sparge water?
- Sparge temperature calibration. Is the sparge water at the correct temperature?
- Wort flow meter calibration. Is the metered wort volume leaving wort separation correct?
Point of reflection: If our mash conversion was as expected, and wort separation instrumentation is all correct, what other reasons might there be for low extract efficiency at wort separation? Give yourself 5-10 min to think about this and then click ‘Next’ to continue this lesson.