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	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
  RE: Correct amount of hops for full-boil ("Tim R")
  Re:Temperature vs. alcohol tolerance ("-s.alexander")
  English Mild recipe help... (Michael Eyre)
   ("Elston Gunn")


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Date: Tue, 13 Feb 2007 07:11:19 -0500
From: "Tim R" <tim.runnette at gmail.com>
Subject: RE: Correct amount of hops for full-boil

I believe Ray Daniels also addresses this topic in Designing Great Beers.  I
like ProMash (http://www.promash.com/) for simplicity.  I've heard Beer
Tools (http://www.beertools.com/) is also good according to this month's
BYO.  

The only place I have not tweaked the numbers is in the case of late
addition DME boils where hops are added early to a full-wort, partial-mash,
low OG wort and then I add the DME during the last 15-30 minutes of the
boil.  I am sure this results in greater utilization.




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Date: Tue, 13 Feb 2007 08:09:09 -0500 (EST)
From: "-s.alexander" <-s at adelphia.net>
Subject: Re:Temperature vs. alcohol tolerance

Bill Pierce asks about yeast performance vs temperature,

Unfortuantely today I'm in hotel room and separated from my reference
material; however there are some clear points (minus a few details),

> I am posting this because of a currently ongoing discussion from the
> Mead Lover's Digest, where someone has posted the recommendation to
> conduct high gravity fermentations at a lower temperature of about
> 60 F in order to increase the alcohol tolerance of the yeast.  As
> evidence they cite the claim that distiller's yeast, which is
> normally fermented quite warm (as high as 100 F because there is
> little concern about the production of fusels), exhibits higher
> alcohol tolerance when fermented at 30 C (86 F).

Alcohol tolerance is a bit of a misnomer.  Common brewing yeast can
ferment effectively into the mid-teens (say 15%ABV) with a little care and
can ferment to the low 20s (20-22%) in studies where osmoprotectants are
added.  So common yeast are typically not up against their limitations
even in wine.

The osmotic pressure on yeast cells increase dramatically as they 1 mol of
glucose to 2 mol of ethanol; a mol of maltose to 4mol of ethanol, and a
mol of maltotriose to 6mol of ethanol.  The increase in  solute molar
concentration in the fermentedd stuff makes it more difficult (as in
requires more energy) for yeast to transport various ions from inside the
cell to out.  This is directly relatable to the concept of "water
activity", Ac, in biology.  Somehow in that semi-magical set of genetic
mechanisms, yeast sense when they are no longer making enough overall
energy to continue economically continue and they instead flocculate (in
the case of commercial yeasts) and go dormant, stop fermenting.

WRT temperature and whisk[e]y - the issue is probably related to
increasing the rate of fermetation and thus improving the factory
throughput.  In Scotch Whisky the wort is in the normal gravity
range(12-15P), common ale yeast - often from local beer breweries was
traditionally used, so alcohol level is not very high.  Also I can't
recall Scotch distillers using such high fermentation temps as mentioned. 
 I can't recall the gravity in US distilling but I seem to recall that it
was somewhat higher.  In both the fermentation is never quite allowed to
finish as their are considerable (5%-ish) ethanol losses in  open
fermenters.

Anyway the primary difference between a successful hi-grav ferment and a
stuck one is the quality of the yeast cell membranes, not the temperaure. 
Yeast cell membranes require oxygen products - UFAs and stereols.  UFAs
are     required for membrane permiability at LOW temps, and pitvching
yeast (their O2 uptake phase) at lower temps causes more UFA  production. 
This is the reason why it's a bad dea to pitch yeast into warm wort then
then later cool the fermenter (esp for very low temps) when you want a
clean ferment.  Yeast do ferment faster at higher temps - up to some peak,
but also product more objectional secondary products, so in beer and wine
we always ferment well below the "fastest" ferment temp.

Also  removal of CO2 and the addition of certain osmoprotectants (certain
amino acids) can greatly aid in a hi-alc brew.  Yeast themselvees can
produce trehalose as a stress reducing substance and tests have been
carried out were yeast were heat treated (mmoentarily brought to a very
high temp) and when they recover their trehalose levels are enhanced and
they perform extremely well for a while.


>  The suggestion is
> that mead and wine yeast exhibit similar properties and therefore
> should be fermented cool in a high alcohol environment.  Extending
> the logic would lead to a similar conclusion for brewing yeast.  I
> must say I have never encountered this recommendation before in my
> reading and study.  Would someone else care to comment?

Well the membrane intergrity is worse at high temps, but I don't believe
that means it is better at very low temps.   My hunch is that anything
much below ~80F will produce similar results for S.cervis strains. Wine
yeast have a greater ability to accumulate sterol than their ale strains
cousins (among S.cerevis).  Of course champagne yeast is a different
critter - more closely related to lager yeast - and should be treated
differently.

Still the methods used to ferment hi-grav are the same.  Be sure you have
enough oxygen product (sterol & UFAs) in your fermenter or you cannot
succeed.   This may mean a well aerated starter or re-aerating yeast
somehow or re-pitching.  Drive off excess CO2 as it stalls the yeast
energy pathway.
 Also incremental feeding (slowly increasing the effective SG) is used to
acheive the very highest ethanol levels.   I am not a mead maker, but I
think that adding honey incrementally should mean that incremental
feeding  is much easier for mead than for all-grain brewing.

later,
 -S





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Date: Tue, 13 Feb 2007 12:24:20 -0800
From: Michael Eyre <meyre at sbcglobal.net>
Subject: English Mild recipe help...

Hey all. Looking for a bit of help in an English Dark Mild recipe I 
whipped out the other week. It's on tap now and I'm getting a bit of a 
'tang' out of it that I'd rather not have, sorta like the Guinness 
taste. I'd rather it was more mellow than it is. Here's the layout:

11 gallons, all-grain:

12lbs English Pale Ale malt
2.25lbs Dark Crystal 150L
0.4lbs Chocolate

2oz EKG 5%AA at 60min
1oz EKG 5%AA at 10min

Safale S-04

One hour at 153 degrees single infusion. Batch sparged. 90minute boil.

3.2%abv all told and a nice dark, mahogany-ish brown color, just like I 
was shooting for. Bitterness seems right on par, with very little, just 
enough to balance. Low carbonation, at about 1.6-1.7 volumes, according 
to my regulator and charts. Thing is, it's that tang I get in the flavor 
that I'm not digging totally. Is that par for the style? Either case, it 
seems just a tad over the top, and I'd like to take the edge off of 
that. I'm basing this recipe of a lot I've seen posted, but mostly from 
data gathered from Ray Daniels book... I' guessing it's the Dark 
crystals that are doing this, but I'm not sure. Any ideas?

Mike


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Date: Tue, 13 Feb 2007 17:09:55 -0600
From: "Elston Gunn" <elston_gunn at comcast.net>
Subject: 

Is there a decent extract lager 'kit' available from one of the usual
on-line retailers?  Or a recipe? Or, is lager really not do-able in the
extract world?  I never brewed a lager, but have done several ales.  Thought
I would take advantage of these cold Minnesota days.




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