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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
		Rob Gardner, Digest Coordinator


Contents:
  Re: Homebrew Digest #241 (August 30, 1989) (Steve "Mr. MBA" Lindahl)
  Attenuative Yeasts (Martin A. Lodahl)
  extract efficiency (Pete Soper)


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Date: Tue, 29 Aug 89 09:23:10 pdt
From: Tom Kuhn <hpda!tkuhn at hplabs.HP.COM>

  OK, for all of you who _hate_ algebra but _can_ plug numbers into a 
formula (or formulas into a program), here is the relationship between
initial specific gravity (SG1) and the temperature at which it was
measured (T1), final specific gravity (SG2) and the temperature at which
it was measured (T2), and percent alcohol by volume (A), corrected to 
60 F.  (All temperatures are F.):


     {0.0190 x (T1 - T2)} + {131.25 x (SG1 - SG2)} = A


Based on Papazian, p. 47:
     
             (SG1 - SG2) x 105 = % Alcohol by weight

             (% Alcohol by weight) x 1.25 = % Alcohol by volume


   and on Doug Roberts (HBD #236)

             (T x 1.449E-4 - 0.009) + SG(uncorrected) = SG(corrected)  




     Now, how should this be corrected for the additional fermentation
which occurs as the result of my priming sugar?  (I would prefer not to 
let some of my precious carbonated elixir go flat so that it's SG can be
measured without CO2.)


Thanks,

Tom Kuhn  (Neither a yo-yo maker nor a philosopher of science)
tkuhn at hpcuhb


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Date: Wed, 30 Aug 89 8:13:16 MDT
From: slindahl at orion.cair.du.edu (Steve "Mr. MBA" Lindahl)
Subject: Re: Homebrew Digest #241 (August 30, 1989)

Please take me off this mailing this....thank you....


-- 
][][][[][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][
slindahl at orion.cair.du.edu     slindahl at ducair.BITNET     slindahl at duorion.UUCP 
               The Devil finds works for idle circuits to do!
][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][][

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Date: Wed, 30 Aug 89 9:18:27 PDT
From: Martin A. Lodahl <pbmoss!mal at hplabs.HP.COM>
Subject: Attenuative Yeasts

In HBD 241, Patrick Stirling asks (concerning yeasts):

> What's 'attenuative'? Sounds like it's the speed with which
> a yeast does its job and goes dormant ...

Aha!  Had you read Miller instead of Papazian, ... 8->  8->

"Attenuation" refers to the degree to which wort sugars are used by
the yeast.  Red Star Ale yeast, for example, munches merrily on
simple and duplex sugars, but has little appetite for the more
complex sugars.  Edme will tackle the triple sugars as well.  I've
only once tried a semi-controlled experiment where I made two
successive batches, varying only the yeast (first Red Star, then
Edme).  I say "semi-controlled", because temperature during
fermentation and fining was essentially uncontrolled, and though the
weather was essentially the same (hotter than the hubs of Hell) for
both batches, there may have been a significant variable introduced
there.  The Edme yeast (considered more attenuative by Miller)
produced a much drier brew (too dry, in fact, for my tastes), but
with fewer initial flaws.  Both resolved well, the Red Star batch in
about 5 weeks and the Edme batch in about 3, with the Red Star batch
always sweeter, fruitier, and with more of the famous banana esters.
The sweetness, in particular, I attribute to the difference in
attenuation between the two yeasts.

> On another tack, what do you think of using ice to cool wort? 

I've had only good luck with this method, but I'm still at
partial-mash brewer.  When I've got my BIG kettle so I can boil the
whole volume of wort (anyone know a good source for 33-quart
enameled steel canning kettles?  Can't seem to find one here), I
won't have ice-dilution as an option any more, alas.

= Martin A. Lodahl    Pac*Bell Minicomputer Operations Support Staff =
= pacbell!pbmoss!mal  -or-  mal at pbmoss.Pacbell.COM      916.972.4821 =
= If it's good for ancient Druids, runnin' nekkid through the wuids, =
= Drinkin' strange fermented fluids, it's good enough for me!  8-)   =


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Date: Wed, 30 Aug 89 12:39:25 EDT
From: Pete Soper <soper at maxzilla.encore.com>
Subject: extract efficiency

"Brian CapouchfEHFTmQ:8:8" <brianc at 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 
much.
  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.

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

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End of HOMEBREW Digest #242, 08/31/89
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