From the HBD Archive
From: Pete Soper <>
Subject: extract efficiency
Date: 1989-08-30 16:39:25 GMT

"Brian CapouchfEHFTmQ:8:8" <brianc@zeta.saintjoe.EDU> says in HBD 241:

>I have a topic of my own: extraction rates on mashed beers. I can't seem to
>ever hit the gravity reading that the writers of books recommend. I'm always
>lower, and I know it's probably because I'm not doing a good job on my mash
>out. Do others also find this common?

I do, although I don't know what the mash out has to do with this. One
time when making a dry stout I got 31.5 points per pound of Briess 6 row
malt. Every other time, using this 6 row, 2 row Klages (Briess), and 2 row
British pale (unknown brand) I've averaged 24-29 points per pound with 28
being the average.
I've traced the source of some of the discrepancy in my case. I use a
"bucket in a bucket" lauter tun with a tap that his fairly high up from the
bottom of the outer bucket. This means that when I'm done sparging there are
about 3 pints of high gravity wort left below the tap (which I don't use,
since it is full of husks).
Another factor is that even after I've created all the wort I can boil
down to a target volume in a reasonable time, the runnings from the lauter tun
have a SG of 1.010-1.1015. The popular literature suggests sparging until the
runnings are 1.008 or less (or the pH rises to 6 or above, etc). So I'm leaving
extract behind in the grain too but on the other hand, at 1.010 it takes a lot
of water to get a little bit of extract :-)
Also, I recirculate my first runnings once the wort is running clear. I
suspect some of this doesn't make it all the way back through the filter bed.
Finally, the above case where I got a reasonably high degree of extract I
also had a lower than usual pH. Usually my mash pH is around 5.6 at the
start of sparging and this is of course higher than optimimum.

> Do they then augment their worts with
>extracts to get to recommended gravity levels, or just smile and not worry?

I've kept track of my average actual extract and use this to scale the
grain amounts to compensate and match gravities. Note that this can go both
ways. Some of the winning recipes in "Zymurgy" reflect INCREDIBLY LOW extract.
I was looking at one recently that used over 15 pounds of grain to get 5.5
gallons with a gravity of 1.050! if I just copied this I'd get a beer with
an OG of around 1.076. It would be too dark, too sweet, underhopped and
generally rubbish compared to what was intended. Going in the more usual
direction, if the recipe writer gets 1.035 per pound per gallon and you
get 1.028, just copying his recipe is going to give you something thin,
too pale and overhopped - not something that would allow me to smile very
Note that I'm reporting my situation to give another data point, not
to describe problems in search of solutions. I especially don't want to
hear anything more about adding teaspoons of gypsum to one's mash, OK? :-)
Incidently, for stove top mashing I've found that a sleeping bag makes a
great insulator for maintaining rest temps. I just put the covered pot on a
piece of cork in the bottom of the bag (on the floor), then wrap the bag
around and over the pot. Protein rests are kept to within a degree of
optimum for 30 minutes, while sugar rests lose only a couple degrees per
hour. This is with a bag rated at 30 degrees.

Pete Soper +1 919 481 3730
arpa: uucp: {bu-cs,decvax,necntc}!encore!soper
Encore Computer Corp, 901 Kildaire Farm Rd, bldg D, Cary, NC 27511 USA

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