The Beginner Brewer: Fixing Things: Low Mash Efficiency

Monday, 2 December 2013

Fixing Things: Low Mash Efficiency

If you've recently started all-grain brewing, you may well be using the Brew-in-a-Bag method as I’ve described elsewhere. Even if you’re not going the BIAB route, one persistent challenge for the all-grain homebrewer is mash efficiency.
That wonderful mash

Simply put, mash efficiency is the amount of actual sugars extracted compared to the total possible sugars that can be extracted from the recipe's grain bill. For many homebrewers, efficiency of between 60-70% is quite common.

On one level, achieving lower levels of efficiency (e.g 50%) is not a disaster. Homebrewing is not a mashing competition, after all. What is far more important is to know the average efficiency of your homebrewery.

Why? Because it affects recipe formulation. If you know that you tend to consistently hit 60%, or 70% or whatever percentage efficiency (as calculated by hand or software), you can modify your recipes accordingly.

To illustrate:

Let’s say you’re brewing an ale recipe with a simple grain bill of 4.5 kgs of Pale Malt, a target OG of 1.050, and a pre-boil gravity target of 1.044.

If you’re brewery efficiency is 60%, you’ll need 5.2 kgs of malt to reach the above targets. But if you’re working at 80% efficiency, you’ll need only 3.9 kgs of malt to reach the same targets. 

So you can see that knowing your efficiency is key to recipes that work out the way they're supposed to.

But what if you want to improve the mash efficiency in your homebrewery?

Here are three tips for getting the most out of your mash!

1. Get the Basics Right.

The alchemy of enzymatic action is waaaay beyond the scope of this post, but suffice it to say that if you want the various amylases to work properly and convert grain starch into sugar, you need to create the correct environment.

So, check that you’re hitting that golden temperature zone of 67 degrees C. Then, make sure that you’re holding it there for at least 60 minutes (preferably 75 minutes for BIAB).

Finally, check that your mash PH is at or around 5.3 – 5.7.

2. Stir the Mash.

Enzymes like beta and alpha amylase need contact with the starch in grains to do their job. Stirring the mash helps with this, and will almost always benefit your efficiency.

Don't whisk the Mash!
Just be cautious: don’t whisk your mash! That can cause so-called hot-side aeration, that affects taste down the line.

A gentle stir, say every 10 minutes or so, should help a lot with efficiency—remember to use a heated spoon to avoid chilling your mash every time you stir.

3. Mashing Out.

So, you’ve done the basics right and you’ve stirred (gently) the mash. 

But your work is not yet done. Especially when using the BIAB method, you can help the washing of sugars from the grain bed by mashing out. To mash out, raise the temperature of the mash to around 75 C and hold for 10 minutes.

This will accomplish two things: first, it stops further enzymatic conversion. Second (and this is the important bit related to our current quest of better efficiency) it makes the wort less viscous and aids in draining sugars from the grain bed.  

That's it: good luck with your mash--but don't forget, this is not a competition folks!

For more tips on fixing things, check out my previous posts on:
Next time, I'll be writing my final (or next-to-final) post for this year, before disappearing into a cloud of Christmas-flavored beer. See you later.

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