Efficiency

[T-SULLI]

I keep hearing things about efficiency. How do you determine efficiency, and what exactly does it mean in brewing?

 

[Hagen]

Efficiency is used when mashing or steeping grain to extract the sugars.

2-row brewers malt can theoretically supply 37 gravity points per pound per gallon. This means that 1lb of the grain's sugars dissolved in 1 gal of water will have a specific gravity of 1.037. This assumes 100% efficiency.

Now, let's say we're going to brew a really simple pale ale, and all we're going to use is 10lbs of 2-row. we're going to collect 6.5 gallons so we have 5.5gal after the boil. Since we're using 10lbs of grain, our theoretical yield would be 370 gravity points. But we have 6.5 gallons, so we divide that 370 by 6.5, which rounds of to 57. That means the theoretical specific gravity would be 1.057.

But when we measure the specific gravity of the wort we collected, it's 1.045. So now, we divide our actual gravity by the theoretical gravity, only using the last two digits in the reading.

45/57=.789 or 79% efficiency, which is pretty good.

That is the actual percent of theoretically available sugars we extracted in our mash. the efficiency can be used to either analyze our equipment and/or techniques for possible flaws, and to tweak our recipes.

EDIT: I can't spell...

 

[T-SULLI]

Interesting. Thanks!!!

 

[maltMonkey]

That's a really nice explanation, Hagen

 

[zythos]

Excellent explanation! I've been wondering about this for several weeks now myself.

 

[riored4v]

Excellent explanation! I've been wondering about this for several weeks now myself.

same here.

I was thinking that I took the runnings directly out of the MLT, but this sounds like it would be tested once all the runnings are mixed together in the kettle. hopefully i'm right.. maybe i'll finally get around to checking my effeciency.


Question though.. if you were doing a PM and only collect say 3 gallons of wort, do you test that 3 gallons, or would you test it after adding rest of the water?

 

[Bobby_M]

In a partial mash, it only makes sense to test the gravity of the wort you derived directly from the mash. This is your "mash efficiency". Once you add malt extract, you'll skew your overall efficiency up towards 100% because it's ALL sugar.

 

[Hagen]

same here.

I was thinking that I took the runnings directly out of the MLT, but this sounds like it would be tested once all the runnings are mixed together in the kettle. hopefully i'm right.. maybe i'll finally get around to checking my effeciency.


Question though.. if you were doing a PM and only collect say 3 gallons of wort, do you test that 3 gallons, or would you test it after adding rest of the water?

Check only the volume of what you mashed/steeped, and collected in the kettle. If you batch sparge, measure the gravity of the total runnings.

If you add water, you're artificially lowering your numbers. Conversely, if you add extract, you're artificially raising it.

You only want to check what actually ran through the grain, and don't forget to adjust for temperature.

 

[Dave the Brewer]

maybe we need to sticky?

 

[devaspawn]

maybe we need to sticky?

Agreed! This is one of the best explanations I have seen for efficiency. Real simple with an example that really makes sense.

 

[Dave the Brewer]

Here is a link that helped me understand a bit http://hbd.org/uchima/tech/efficiency.html
Just to add to the great info!

 

[Blender]

maybe we need to sticky?

A lot of this type of thing is already in the Wiki.

https://www.homebrewtalk.com/wiki/index.php/Efficiency

 

[riored4v]

Check only the volume of what you mashed/steeped, and collected in the kettle. If you batch sparge, measure the gravity of the total runnings.

If you add water, you're artificially lowering your numbers. Conversely, if you add extract, you're artificially raising it.

You only want to check what actually ran through the grain, and don't forget to adjust for temperature.

ok, thanks.

(thanks to bobby as well)

I think this might actually make sense to me now:rockin: