When it comes to critical steps in preparing a distillers wash, achieving the perfect distilling crush is one of the fundamentals.
You will often hear us speak about Grist Fractions or Grist Ratios.
We are talking about 70:20:10. The starter for Ten when it comes to preparing your grist.
All brewhouses perform differently and like people, have a preference as to how their foodstuff is prepared. By using a grist consisting of 70% Grits : 20% Husk : 10% Flour it gives us a good starting position to assess mashing performance to then enable optimisation.
Absolutely they do!
Each of the fractions perform a different function in the mash.
The Husk is our filter bed. In the absence of a full lauter tun we rely on this filter bed for efficient wort separation or filtration.
The Flour carries some extract and enzymes and is sensitive to both temperature and being lost in suspension below the tun plates and pipe runs.
The Grits really are the nitty gritty! This is where the bulk of your extract is. A well-sized grit contains enzymes and starch bundled in the perfect size to hydrate well at the correct temperature.
The vast majority of distillers use 3 waters in their process. 1st waters or strike liquor, 2nd waters or sparging liquor and finally, 3rd waters, an extra hot sparge that is collected back to hot liquor tank to be used as the strike water of the next mash.
It is easy to fall into the trap of thinking that, because there is so much liquor at 3 different temperatures in contact with the grist, you will extract everything that there is to extract whatever the grist fraction looks like. This is not the case.
If the crush is too coarse, for example, you may see starchy endosperm stuck to the husk and the white lumps of free starchy endosperm (The Grits) will be quite large. Due to the excess size, complete hydration of the starch granules will not occur at the correct temperature. You will not gelatinise the starch and allow conversion into fermentable sugar. You will likely end up with 3rd water recovery issues because the starch will form a glutinous soup which will not separate. Mash Tun yield will be low and Spirit Yield poor.
If the crush is too fine, you will see a lot of flour and the husk will be broken down too far. The smashed-up husks will not form an effective filter bed so you will experience slow run-off, poor wort recovery and low yield. If your flour fraction suspends in your liquor and slips quietly away below your plates or into pipe runs it is unlikely to sit at the correct temperature for conversion to happen thus a loss of extract and yield.
The perfect crush will give you swift and efficient conversion and run-off whilst maintaining high fermentable extract and thus yield.
Analyse your grist.
Clean your sampling tube on your mill.
Grab your Shooglebox / Shuttlebox / Gucci Automatic Shaker Sieve and give that a thorough clean too. We need the results from this grist fraction analysis to be accurate.
Run your mill and take a grist sample about a third of the way into your milling run. This is to ensure you have cleared any flour from the tail of the last run.
Undertake your fraction analysis according to your usual procedure. My personal method, using a good old fashioned wooden shooglebox can be found in the post script below.
Deep Dive the results and consider optimising your mill.
What are you seeing in your fraction results?
Flour too high? Grits too low? Open up your bottom set of rollers a touch.
Husk too high?
Have a very careful look at the husk fraction.
Are there any whole, uncrushed corns? Yes?
Check your mill rollers are parallel and not excessively worn into a curve. Uncrushed grain is 100 percent loss of extract and yield and is not acceptable in any amount in your grist.
Is there white starchy endosperm sticking to the husk? Yes?
This is artificially skewing your husk fraction weight. If your flour fraction is near to 10, close up the top set of rollers a touch to increase the initial crush.
Husk fraction too low? Open up the top rollers a touch.
Grits too high? This one is interesting as a high grist fraction is no bad thing as long as it isn’t being caused by the presence of excessive husk.
Re-run your mill on the new settings and re-sample the grist.
It won’t take long to get your mill dialled in.
Post ScriptStuart’s Shooglebox Method.
I am a scientist. The devil is in the detail and consistency is key. Don’t judge me on this!
Clean your box thoroughly. Grab your scales that weigh to 0.01gram. Anything less is not accurate enough.
Weigh each part of the box and record the weights of each individual part.
Assemble the box and weigh-in a set amount of your sample. I generally sim for 100 grams so it keeps the maths easy down the line.
Now for the fun bit!
Set a timer running and shoogle the box forward and back for 15 seconds. Aim to move the box about a foot. At 15 seconds tap the box twice on the tabletop and change direction to left and right. Again, moving about a foot. At 30 seconds, 2 taps and change back to forward and back. Continue, without stopping, until 3 minutes is up.
Open up the box and weigh each of the sections. Record the section total weights. Subtract the starting weights of each section which, you guessed it, will give you the sample weights of each fraction. Clean the box up, grab a brew and a Tunnocks, you will need it after all that shoogling!!
You will never get exactly 70:20:10 but you should be able to get fairly close and by using the above method you should be able to achieve good repeatability of results.
Next Up…
The Magic of the Perfect Mash.
