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General Category => All Grain Brewing => Topic started by: bluedog on June 19, 2010, 08:29:25 AM

Title: Mash efficiency
Post by: bluedog on June 19, 2010, 08:29:25 AM
Why does my efficiency go down when I make big beers? I mashed 19 lbs of grain the other day and got 7 gallons of 1.054 wort. I wound up adding DME to the boil to boost my gravity. Doing the math I should have been in the low 1.090's (post boil) with 75% efficiency. So what's going on? I don't have this issue when I make 1.050/1.060 beers. I usually come in higher than I expected with somewhere like 80% effeciency. I have a RIMS set up and fly sparge. I would add extra grain to the mash if I could but my set up is maxed out at 20lbs.
Thanks in advance...
Title: Re: Mash efficiency
Post by: Kaiser on June 19, 2010, 10:56:25 AM
With big beers you may have a double whammy when it comes to efficiency. Starch conversion in thick mashes is slower and may not be complete by the time you lauter. And the lauter is less efficient b/c the larger grist retains more wort and with it sugars. This is particularly true for batch and no-sparge but also applies to fly sparging to some extent.

Next time you brew a big beer check the conversion efficiency by dong a [http://braukaiser.com/wiki/index.php/Troubleshooting_Brewhouse_Efficiency#Determining_Conversion_Efficiency mash gravity test] which tells you how much of the starch has been converted so far.

You can also test the grain bed for retained sugars by running this [http://braukaiser.com/wiki/index.php/Troubleshooting_Brewhouse_Efficiency#Testing_the_lauter_efficiency_.28fly_and_batch_sparging.29 lauter efficiency test]. There is also a nice spreadsheet on page that helps you with the calculations.

Kai
Title: Re: Mash efficiency
Post by: bluedog on June 19, 2010, 12:20:20 PM
Thanks Kai. If I was able to thin the mash by adding additional water and slowing the sparge rate down do you think extraction would improve?
Title: Re: Mash efficiency
Post by: a10t2 on June 19, 2010, 03:01:16 PM
As Kai said, check your mash gravity when you pull the first runnings. That will let you know if you have conversion issues, or normal lautering losses.

Adding additional water will definitely increase efficiency. If you mash and sparge with the same amount of water per pound of grain, your efficiency should stay constant. So if you get 80% efficiency for a 1.050 beer with a pre-boil volume of 7 gallons, you could still get 80% efficiency on a 1.090 beer, but you'd have to run off about 12.6 gallons (and boil for several hours). From a practical perspective, it's cheaper to use more grain than to maintain the longer boil.
Title: Re: Mash efficiency
Post by: babalu87 on June 19, 2010, 06:26:01 PM
it's cheaper to use more grain than to maintain the longer boil.

True but longer boils have their benefits too  ;)
Title: Re: Mash efficiency
Post by: dean on June 26, 2010, 04:24:58 AM
Longer mashes are less expensive and you can do other things while its mashing.  A four or five hour mash won't hurt anything and it helps increase your efficiency and you'll have time to run to the LHBS if you forgot something even.   :)  The worst that can happen is your mash temp "might" drop a degree or two depending on your tun.
Title: Re: Mash efficiency
Post by: bonjour on June 26, 2010, 08:12:35 PM
it's cheaper to use more grain than to maintain the longer boil.

True but longer boils have their benefits too  ;)
;D ;D ;D
yes they do
Title: Re: Mash efficiency
Post by: BrewArk on June 27, 2010, 06:12:12 PM
... A four or five hour mash won't hurt anything ...

I thought that if you left it for that long you would loose some dextrines in favor of more fermentables?  If you are looking for a good session beer, it wouldn't be as good as if you were looking for a silver bullet.

That said, it could be accommodated for with the proper grain bill.  Most on this forum probably aren't using 100% 2-row so perhaps I should stop writing this & have another homebrew.

-Cheers
Title: Re: Mash efficiency
Post by: dean on June 28, 2010, 07:38:53 AM
Not trying to change the subject, but I made a sour ale that I let the mash sit almost 96 hours, you would think the wort should have a lot of noticeable tannins from the ground husks causing astringency, but so far I cannot tast any astringency.  Maybe because its sour, I don't know, but it makes me wonder if boiling doesn't have some effect on releasing or intensifying the tannins?  Another thing, this sour ale was a No Boil, I mashed at 147* when I started and had ~82% efficiency straight out of the mashtun into the fermeter 4 days later.  The beer is slightly sweet too (last time I tried a sample anyway), which is apparently a flaw for a sour ale.  Its still fermenting very slowly beneath its pellicle.

The OP wanted to increase his efficiency and longer mashes seem to have a huge effect on my brews... just how much I would suppose is debatable.