---

	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
		Digest Janitor: janitor@hbd.org
		Many thanks to the Observer & Eccentric Newspapers of 
		Livonia, Michigan for sponsoring the Homebrew Digest.
				URL: http://www.oeonline.com


Contents:
  AOL home brewing message boards (BsmntBrewr)
  enjoying yeast discussion plus question (John_E_Schnupp)
  Re: FAN/amino acids in yeast nutrient (patrick finerty)
  Re: liquid yeast in toronto (patrick finerty)
  Off Flavors/Wyeast/FAN/Pitching/Skunkiness/Water ("A. J. deLange")
  Liquid Yeast in Toronto ("Rob Jones")
  Decotion heat source...does it matter? (William Macher)
  FAN and fusel alcohols (Dave Burley)
  Pitching Rates (KMacneal)
  Airstone Carbonation (Dan Listermann)
  WATCH ("MrWES")
  high temperature wort settling ("Stephen Alexander")
  contaminated yeast/Fusels/Yeast  (starter) Questions ("Stephen Alexander")
  more pitching rate ("Alan Meeker")
  contamination (Aaron Perry)


* Beer is our obsession and we're late for therapy!

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----------------------------------------------------------------------


Date: Sat, 19 Feb 2000 00:04:55 EST
From: BsmntBrewr at aol.com
Subject: AOL home brewing message boards

Greetings brewers,

I would like to invite any AOL based HBD subscibers, Pat says there's a bunch 
of you, to check out the AOL homebrew message boards.  Yes they are out there 
but impossible to find.  In fact I can't find the boards without my "Favorite 
Places" link.  Pat Babcock is a moderator on the boards and regularly 
participates.  Marty Nachel, author of Home Brewing for Dummies, is also a 
another notable regular contributor as well.   

The boards are no substitute for our beloved HBD but are a great resource as 
an addition to it.  One of the best features is that there are atleast 37 
different catagories of brewing topics that you can post to or just browse at 
your leasure.

To get there open your Favorite places and click on the "new" button.  You 
will be prompted to enter a name for the new link and the "internet address"  
Just copy and paste the following line of text into the internet address 
field and save it.

aol://5863:126/mB:185893

To get there just click on your favorite places option then click on the link 
you just created.  If you have trouble doing this email me and I'll send you 
a hyper link in your mail.  

No flame suits required, we're a pretty easy going bunch.  Pop in and say hi.

Brew On!
Bob Bratcher
Roanoke, VA
Star City Brewers Guild
<A HREF="http://hbd.org/starcity">http://hbd.org/starcity</A>


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Date: Sat, 19 Feb 2000 00:46:00 -0800
From: John_E_Schnupp at amat.com
Subject: enjoying yeast discussion plus question

Digest 3250 is full of yeast info.

>From: "George de Piro" <gdepiro at mindspring.com>
>I find it safest to not provide continuous aeration, but rather
>to aerate for several hours, let it ferment out, and feed and aerate again
>the next day.  This has worked for me.  Results may vary, and I'm sure their
>are others who will chime in with alternate techniques that provide good
>results.

I use stir and aerate continuously.  I use a HEPA filtered aquarium pump to
get fresh air into the top of my starter vessel (4L wine jug).  I do not
bubble the air thru the starter.  Use a two hole stopper and pump air in
one hole and attach an air lock to the other.  The stirring action will
provide enough (I told) aeration.

I typically start with a smack pack into about 1 pint.  Approximately every
24 hours I add another quart.  I usually add 2 quarts.  I stop the aeration
several hours after the final quart and keep the stirrer going.  When the
bubbling has slowed, I stop the stirrer so that the yeast can settle.  I like
to allow at least 24 hours for this but have gone less.  On brew day I drain
the spent liquid and add a fresh quart after I have the mash going.  By the
time I'm ready to pitch the yeast is at full trot.  I used to think that folks
who said they had lag times of 2-4 hours were nuts, now I know better.

>From: Spencer W Thomas <spencer at engin.umich.edu>
>You want 8mg/l of O2 dissolved into the wort.  The 1.7 g of O2 in the
>carboy divides out to 90g/l, assuming 19 liters of beer in the carboy.
>So, yes, there is plenty of O2 in the headspace.  How about that!

I made an aeration tube for the drain from my brew pot.  I used the tip from
a butane lighter.  I used one of those grill lighters.  The fuel tip was
brass and the opening is very small.  I drilled the correct sized hole in the
as long as it takes to fill empty the brewpot.  My drain is 3/8" copper so
it takes a little longer.  I've never noticed anything that would indicate that
I'm not getting enough aeration.

>From: "Parker, Mike" <mparker at CaseServices.com>
>You don't need a microscope for counts.  You pull a 1 ml sample
>sample from that, dilute x 10 again, and repeat for something like
>6 times total.  Then pour the last 10ml sample onto an agar petri
>dish, let it grow a day or so, then do an eyeball count.  If you
>diluted right you should get around 10-100 colonies.  Back-calculate
>by multiplying your count by 1x10E<#dilutions> to get your count/ml,
>then multiply by your starter size to get the total count.

Never though of this.  This sound like a very "quick and dirty" way to get a
good idea of cell counts.  I don't have a scope and wasn't really planning
on it, but I've always wondered about what kind of cell count I was getting.
I've never grown anything on an agar petri dish.  I'm assuming that it
would/should be obvious to tell the differenct between a yeast colony and
a bacteria colony.  IOW, wouldn't this also be a rough test for possible
infections?

Question:  based on my above starter method, when should I pull the first
10 ml sample?  When I'm ready to pitch or from the slurry before I add my
final refresher wort on brew day?  I would think the best time would be
right before I pitch but at that point there's so much foam that it'd be
hard to get all the yeast suspended into final quart of starter liquid.
I would also think that 10 ml of very thick slurry should have more yeast
than a slurry that hasn't had time to settle as much.  Kind of a subjective
thing I suppose, but adequate for a ballpark idea.

John Schnupp, N3CNL
Dirty Laundry Brewery (temporarily closed)
Georgia, VT
95 XLH 1200




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Date: Sat, 19 Feb 2000 09:42:40 -0500 (EST)
From: patrick finerty <zinc at zifi.psf.sickkids.on.ca>
Subject: Re: FAN/amino acids in yeast nutrient

hi,

i'm not really a yeast expert but i'm feeling brave so i'm going to
give it a try. 

On February 18, 2000, Fred L. Johnson wrote:

 > To the yeast culture experts out there:
 > 
 > Could someone provide a brief summary of
 > 1) the requirement for free amino nitrogen by yeast for growth, (i.e.
 > is free amino nitrogen "required" for growth or just to prevent fusel
 > alcohol production?)

like all living organisms, yeast need to make nitrogen-containing
macromolecules (proteins, nucleic acids) to survive. as such, they
require a source of nitrogen. nitrogen can be supplided as free amino
acids or as NH4Cl (ammonium chloride). free nitrogen should not be
necessary if there are enough of all amino acids present in the wort.
i know deamination reactions are nearly absent in bacteria when they
are grown in a media containing sufficient amounts of all 20 amino
acids (i prepared some 15N-Leu labeled protein this way last summer).
obviously yeast aren't bacteria but i'm going to take a risk and
assume they would behave similarily. the deamination reactions are
used to make one amino acid type using a different type as the
starting point.

 > 2) the amino acid requirements by yeast for growth

yeast do not require amino acids for growth. rather, they can make
them using only NH4Cl and a carbon source (glucose). in the lab yeast
can be grown using a very simple minimal media containing NH4Cl,
glucose, a phosphate source (usu Na(2)H(2)PO4) and a couple of
vitamins (enzyme cofactors).

 > 3) the concentrations of the above that can be expected in all grain
 > worts, and

can't really answer this but i can say it will vary depending on the
type of grain you use. perhaps the company that does the malting has
done an analysis of the amino acid content of their grain.

 > 4) the situations in which supplements to the wort might be required?

the only time i ever hear about people adding supplements regularily
is when making meads. in that case you have a very high gravity liquid
that will require the yeast to ferment for a long time (ie, keep
living for a long time). since honey doesn't really have much in the
way of amino acid or nitrogen content the yeast need it provided to
them.

 > In regard to the above questions, I have seen diammonium phosphate as
 > a common ingredient in "yeast nutrients". Is this to prevent fusel
 > alcohol production, or is this to enhance yeast growth, or are these
 > issues not related?

i assume it is to provide yeast with nitrogen when the growth media
(say wort prepared with DME) is defficient. when a particular amino
acid type is defficient, deamination reactions will be employed to
make that amino acid. i don't think providing yeast with something
like NH4Cl will stop these reactions. however, i may be mistaken. 

 > Protein hydrolysates and peptones are also typcially found in "yeast
 > nutrients".  Apparently amino acid concentrations can be deficient at
 > times.  I assume these are necessary under conditions in which amino
 > acid concentrations are low (musts?).  I also have seen added thiamine
 > in mixtures of "yeast nutrients" or "energizers" for homebrewers.  I
 > assume this is an essential amino acid that con be deficient in worts
 > (or perhaps only in musts).

many hydrolysates such as peptones are made from yeast. it is sort of
strange to grow yeast on hydrolysates of yeast but they're really
quite happy growing in it. when i grow yeast for brewing in the lab i
always start with YPD:

10 g yeast extract 
20 g Peptone 
1 liter dH2O 
adjust pH to 5.8 with HCl 
autoclave 30-45 minutes and cool to 65 degrees C, then add 50 ml of
sterile 40% glucose 

actually, for this last batch of beer i grew the yeast in YPD the
whole time and simply collected the cells by centrifugation,
resuspended in some wort and then pitched. i'd be curious to hear when
people thought about using YPD the whole time like this as far as
flavor of the beer is concerned.

thiamine is vitamin B1. it is an enzyme cofactor. here's a nice link
all about thiamie: http://chemistry.gsu.edu/glactone/vitamins/b1.

 > I would like to better understand the driving force behind fusel
 > alcohol production (which, of course, can be a flavor problem with
 > beer) versus the limitations on yeast growth.  I wish
 > to better understand the issues behind making yeast versus making
 > beer, so that I can control these at the APPROPRIATE TIME during the
 > process.  Culturing yeast for brewing is not the same as brewing beer,
 > and the two processes should not be confused.

i think a simple guide is to grow the yeast initially in the best
media you can produce. this probably means using something like YPD.
prior to pitching, you will probably want to use wort, possibly
supplemented with yeast nutrients if the wort is thought to be
deficient. 

i thank those who are more knowledgable about yeast metabolism for
being kind when they point out the errors in this post!

 -patrick in toronto

- -- 
       "There is only one aim in life and that is to live it."
 Karl Shapiro,(1959) from an essay on Henry Miller's Tropic of Cancer
	      finger pfinerty at nyx10.nyx.net for PGP key
		 http://abragam.med.utoronto.ca/~zinc


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Date: Sat, 19 Feb 2000 09:49:04 -0500 (EST)
From: patrick finerty <zinc at zifi.psf.sickkids.on.ca>
Subject: Re: liquid yeast in toronto

howdy rod,

you can get liq yeast from Brew-Your-Own, LTD. they're just down the
street from the U of T at McCaul and Baldwin. Barry, the owner, is a
pretty knowledgable and helpful guy. i was just there yesterday to
pick up my shiny new Valley Mill...

call them at 977-2289.

 -patrick in Toronto (std disclaimer...)


On February 18, 2000, Rod Kwok wrote:

 > 
 > hi,
 > i was hoping that someone on this news group could point me towards a 
 > source for liquid yeast in toronto or at least in ontario.  i've 
 > contacted white labs (a while ago) and their closest source i think was in 
 > ohio.  i don't think i got and answer from wyeast.  my problem with mail 
 > order from the states is that the shipping rates are usually double (or 
 > more) when the package passes the border.


Return to table of contents


Date: Sat, 19 Feb 2000 15:11:02 +0000
From: "A. J. deLange" <ajdel at mindspring.com>
Subject: Off Flavors/Wyeast/FAN/Pitching/Skunkiness/Water

Wil Kolb asked about doping beers for training. This is invaluable. Some
of the chemicals (acetaldehyde, diacetyl, ethyl acetate, ethyl
hexanoate, geraniol, etc.) are readily enough available to anyone who
works in a laboratory but will be difficult to obtain otherwise and they
are somewhat expensive. There is a company in the UK called FlavorAktiv
(I think that's how it's spelled) that sells nifty little kits for
exactly the purpose Wil has in mind. The off flavors are bound up in
powders in little capsules. Just add to water or megabrew and you're off
and running. You know there has to be bad news here. The cost is
astronomical - so bad that their literature suggests that several small
breweries in an area may wish to pool their funds to buy one kit.
Several home-brew clubs might do the same.

For DMS offer Rolling Rock. For mercaptans see "to Dr. P" below

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* * * * * *

Several of the times I've put the contents of a Wyeast package under the
microscope I've found a thing or two that isn't a yeast cell. I've never
had a bad result from proper use of a Wyeast product. Put those two
facts together and I hope what is the essential truth will emerge.
Wyeast cultures are not pure but grown up properly the occasional
stowaway bugs haven't a chance. Note: I also find grains which are not
barley in the malts I buy.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* * * * *

Let me have a whack at a couple of Fred Johnson's questions - I'm sure
others can fill in where I'm thin.

>1) the requirement for free amino nitrogen by yeast for growth, (i.e.
>is free amino nitrogen "required" for growth or just to prevent fusel
>alcohol production?)

   I'd say "both". Yeasts, like other living things, require amino acids
for the formation of protein (including the enzymes we rely upon to turn
sugar to alcohol) and thus need them to grow and reproduce. Some amino
acids can be synthesized, some must be supplied. Because they  are
needed for growth yeast  will synthesize them if they are not supplied.
The problem is that synthesis sometimes uses pathways which branch to
fusel production. Often the amino acid produced by this same pathway has
an inhibitory effect on an early step. For example, valine blocks alpha
acetolactate synthase slowing conversion of pyruvate to acetolactate and
thus reducing the amount of isobutanol (and, as an added benefit,
diacetyl) formed by the valine  synthesis pathway. Thus, a hefty valine
level is desirable in wort for two reasons.

>2) the amino acid requirements by yeast for growth

I'll leave this one to the experts but I seem to remember seeing 200
mg/L as a lower limit for wort.

>3) the concentrations of the above that can be expected in all grain
worts, and

 The following are some FAN numbers from my brewing logs. All are in
mg/L
Ale  217
Pils 352
Fest 369
Weizen 197
Pils 354
Pils 369

It's quite clear that the lagers have a higher level than the ales. All
the lagers are decocted (but so is the Weizen)

>4) the situations in which supplements to the wort might be required?

I think a rule of thumb might be when it falls under 200 but that's a
rule of thumb subject to all the caveats that go with rules of thumb. If
you brew a tasty beer with a FAN of 100 pitched at a million cells/mL,
enjoy it!  Extracts are notorious for being low in FAN but the one or
two I've measured did not confirm this. I seem to recall an article in
one of the magazines where a whole bunch of extracts were tested.

* * * * * * * * * * * * ** * * ** * * * * * * * * * * *

Just got to put in my oar on the raging pitching level debate. There
seems to be a feeling among some that if it's in a textbook or done by a
megabrewery, it's wrong - that it's got to be artisanal to be good.
Horse feathers!  Megabrews are, like American movies and television,
technically superb - just insipid. While the basic premise that
eccentric practices can, and do, produce excellent beers is certainly
valid there are few, if any of us, on this forum well enough grounded in
the fundamentals that we can dismiss them out of hand. You'd better
sweat through the Czerny before attempting the Goldberg Variations.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

To Dr. P: Try the skunking experiment with half an hour of direct
sunlight. With a beer that hasn't been brewed with preisomerized (I use
American Budweiser for this demo) hops your panel shouldn't even have to
taste the beer. I've had classes gasp as soon as the crown is removed.

And my test tube is just as large as it needs to be!

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *

For Jeff Lutes: Weird water report - not that the water is so weird but
the data. As a brewer you don't care about ppb levels of heavy metals
(you do as a consumer though). You need to know alkalinity (or
bicarbonate level), sodium, potassium, hardness (magnesium, calcium).
These are usually present in much larger quantities than things like
zinc and are usually reported.

Given this limited data I can only roughly estimate the alkalinity of
the water at about 30 ppm as calcium carbonate and the bicarbonate level
at about 36. Any magnesium, potassium or sodium present, and there must
be some, would raise this estimate somewhat but I don't think by much
because if the alkalinity had to go higher the pH probably would
probably be higher than it is.

In any event, the water looks pretty good for brewing. Given the
estimated alkalinity level you should have no trouble establishing mash
pH for the majority of brews and no trouble controlling it with high
kilned malt or chalk where necessary. The low level of sulfate means
that brews with high levels of fine hops can be done. For Burton style
ales, Exports, etc., sulfate can be supplemented with gypsum,





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Date: Sat, 19 Feb 2000 09:51:21 -0500
From: "Rob Jones" <robjones at pathcom.com>
Subject: Liquid Yeast in Toronto

Rod,

Contact Brew Your Own, downtown on McCaul St. Barry carries a good selection
of Wyeast, White Labs and Yeast Lab, all fresh. He's also a good source
(basically the only source in Toronto) of info and supplies on all grain
brewing.

Phone 416-977-2289

Good brewing,
Rob Jones
Secretary, Canadian Amateur Brewers Association
http://realbeer.com/caba/


Date: Fri, 18 Feb 2000 09:41:59 -0500 (EST)
From: Rod Kwok <rdkwok at zoo.utoronto.ca>
Subject: liquid yeast in toronto





Return to table of contents


Date: Sat, 19 Feb 2000 10:09:50 -0500
From: William Macher <macher at telerama.lm.com>
Subject: Decotion heat source...does it matter?

Hi All,

Ok! I have a confession! My name is llib rehcam. This 
Macher thing is just a pseudonym I use to prevent fires 
when posting to the HBD, which I rarely do anyway...Oh 
my, a dilemma! Why am I using this Macher handle in real 
life? Or am I? Better cover this with my wife in the 
morning...but she is a refugee from napaJ...not sure if she 
counts...guess I better consult with selected posters from 
this forum later....It's just that as a young boy years ago I 
could not explain why a first name could be a last name. 
Yea, that must be it...which came first anyway?

I love my HBD. I love my HBD...my morning chant on the 
way to my...my...my favorite reading spot!

Gee, am I the only one that knows that Dr. Pivo is real and 
in another existence goes by the name of Jeff? My, 
my...what happened to Arnold Chickenshorts? He certainly 
had more substance to post here than many of us. Did we 
have to drive him away because he did not stand behind an 
identifier that made us feel comfortable? I keep thinking his 
name might be George...No, I mean the other George, the 2 
+ 2 one...Will I be flamed because my name seems real? 
Doubtful. Are you certain it is?

George De' probably does have the ability to split beers in 
to the many taste components that are there. Should we  
drive him down because this is so, or because he thinks it is 
so? Chances are it is so. So?

Would be nice if Al K. dropped by again sometimes. But 
three little ones can take so much of one's time...Dave B 
does go on and on...I am glad he is here even if he did 
stress the big "C" pretty heavy for a while. You know what 
"C" I mean...

Steve A and A. J. your posts are always appreciated. I am 
sure even a bunch of us appreciate the spinning cat 
stories...Jack S. spins a tail or two too...or is that 
tale...oh...whatever...All the other regulars thanks to you 
too...alan and alan are you the same or different?

This Belgian style ale I have been sippin' for a bit is pretty 
goo...on to my question, here, here!

Decoctions by fire versus steam.

I know most decoctions are done over a flame of some sort. 
Would it be likely that a decoction that was heated by 
injection of steam into the vessel holding the decoction 
would produce the same results? It would be easy for me to 
set up a steam heated decoction vessel, but much less 
convenient to install a burner to use as the heat source.

My uncertainty is whether the flame actually caramelizes 
[oh, oh! Another spelling error? Tsk, tsk...] the grains due 
to overheating at the interface with the bottom of the pot. 
Would it be likely I could get the same result if I used 
steam to boil the grains rather than a flame under the pot 
holding them? With my setup the steam would not exceed 
about 220 degrees F. Gee I said grains...better cover that
with "thickest part of the mash..."

Fire VS steam for the decoction heat source. Any practical 
difference?

Appreciate any opinions or experience. 

By the way, you know what really amazes me? Well, in 
previous travels I REALLY LIKED some of the beer in 
England, and in Belgium and Holland and Germany and the 
Chec Republic and France and...and... And I really DID 
NOT LIKE some of the beer in England, and in Belgium 
and Holland and Germany and the Chec Republic and 
France and..and...

Bottom line is I know there is a wide spectrum of tastes out 
there in the real WORLD. I know that my homebrew falls 
within this spectrum somewhere. Tastes good to me, and to 
others (who may like it simply because the price is right). 
What do they know anyway? The spectrum is broad. My 
guess is many do not know how broad it really is...Under 
pitching of yeast [by our American standard] may not be as 
evil as some portray it to be. It is still a big world out there.

Napal and napaJ are not the same place by the way. 
Refugees from napaJ are few and far between, that is what 
makes mine so special!

Beer by any other name is just another pivo!

Swingin' tails in Pittsburgh, Pa USA...or is that singin' 
tales? Better check our karaoke machine...this mike looks 
so much like a mouse...why aren't those speakers workin' as 
I sing into this thing???? What's goin' on here...How'd this 
glass get empty so quick. Which one of you kids has been 
sneakin' up here???!!! what's HBD mean...where am I?

Have bun...ah... FUN!

If i knew where I was I'd tell ya'

Jeff! I need help! No, not the pivo Jeff! I mean the the Jeff 
we all revolve around!

Jeff! Where am I....................?

llib rehcam

PS - Eric...or was that Erik? I want one of these pocket 
cobras...how'd you do that?




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Date: Sat, 19 Feb 2000 10:24:48 -0500
From: Dave Burley <Dave_Burley at compuserve.com>
Subject: FAN and fusel alcohols

Brewsters:

Fred asks about FAN ( free amino
nitrogen) and fusel alcohols and
related subjects.

FAN are non-protein, non-ammonia
nitrogen which can be assimilated
by yeast. This includes amino acids,
amines and whatever low molecular
weight organic compounds with
nitrogen attached to a carbon
including low molecular weight,
LMW, peptides. FAN does not
include 'ammonia' as far as I know.
FAN is closely related in content,
but not TSN ( total soluble nitrogen),
which also includes ammonia/um
compounds. FAN and TSN are
important for yeast growth and low
attenuation, since it relates to the
health of the yeast colony. If you
reduce the amount of  FAN or TSN
too much, such as putting too much
sugar into an extract batch, you
will reduce the nitrogen content
too much and likely you will end
up with an underattenuated batch.
Yeast nutrients often add ammonium
phosphate as a way of boosting
TSN.

As Fred notes, some nutrients
add hydrolysed protein as a way of
boosting FAN without adding salts
and risking the precipitation of
calcium with the addition of
phosphate. Peptones are
sometimes added and would
provide LMW peptides for yeast
utilization at the expense of higher
MW proteins, not always a good thing.

Although I have read elsewhere
that yeast preferentially utilizes
ammonia/um compounds until these
are depleted and then goes after
other sources of nitrogen, namely
the FAN, M&BS says the ammonium
ion ( often called "ammonia") may
or may not be utilized, depending
on the yeast strain and that it utilizes
amino acid nitrogen preferentially.
( M&BS 2nd ed.  p 596).

 When yeast uses an amino
compound it removes the nitrogen
( deamination) and in the place of
the N-H substituent is substituted
an O-H or C=O.  If this is a primary
amine ( on the end of the carbon
chain) it can form a a fusel alcohol.
This is is an alcohol with a carbon
chain longer than 2, so it is called
a fusel alcohol, since it is part of
the residue left after beer
distillation. The lower molecular
weight fusel alcohols are
solventy smelling and have high
vapor pressures, so can have a
real impact on beer aroma even
at low concentrations.  Fusel
alcohol formation is a function of
yeast growth and amino nitrogen
metabolism.  

Also:
M&BS 2nd ed. p 599 

"Since the yeast oxo-acid pool is
derived from both carbohydrate
metabolism and wort amiino
acids, both may serve for
generating these precursors of
fusel alcohols."

M&BS says ( 2nd ed p 601)

"Apart from the particular
properties of yeast strains, the
principal factors leading to
elevated fusel alcohols in
brewery fermentations are
1) elevated levels of amino acids
in worts
2) anaerobic conditions
3) high temperature
4) continuous agitation
5) large amount of yeast growth
6) high alcohol concentration"


Apart from the continuous agitation
comment, these are biochemical
phenomena. Anyone care to
explain how agitation causes the
formation of fusel alcohols?


Keep on Brewin'


Dave Burley


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Date: Sat, 19 Feb 2000 11:41:14 EST
From: KMacneal at aol.com
Subject: Pitching Rates

In a message dated 2/18/2000 12:26:11 AM Eastern Standard Time, "George de 
Piro" <gdepiro at mindspring.com> writes:

<< The flavors that
 most beers  will acquire from yeast abuse (i.e., underpitching) are NOT
 pleasant to most people.  If you like the solvent flavor of ethtyl acetate
 or the heady, harsh character of fusel alcohols, by all means underpitch
 your wort.  Most people do not like these flavors, though.
 
 A "full-flavored" beer will express its fullness in malt, hops and balanced
 yeast by-products that result from a healthy fermentation.  Messing with
 your yeast (underpitching and/or underoxygenating) will yield unpredictable
 and often unpalatable results.  You most certainly cannot expect to harvest
 and repitch yeast from such a fermentation.
 
 This is really a pointless argument.  Countless commercial brewers and
 brewing scientists have demonstrated the results of "proper" fermentation
 management.  If a couple of homebrewers, whose beer most (none?) of us have
 ever tasted, wish to question these well-tried practices, that is fine.  Be
 aware that these guys are in the minority, though, and unless you taste
 their beers and find them acceptable, question their assertions. >>

Like I said in an early post, I follow the recommendations of the homebrewing 
texts and the Classic Beer series and pitch a 1 pint starter for ales, a 1 
quart starter for lagers, and a 1 gallon starter for high gravity beers 
(scotch ales, doublebocks, etc.). I aerate the wort by pouring it through a 
strainer into the fermenter after chilling and then doing some stirring. The 
score sheets I've received from BJCP certified judges have never mentioned 
the defects George lists above.  I can understand the need for commercial 
brewers to pitch large quantities of yeast -- they want to turn beer around 
as fast as possible and minimize potential sources of batch to batch 
variablilty.  As a homebrewer with other things competing for my time, I find 
an acceptable trade-off between these alleged underpitching rates and the 
time and effort needed to grow large starters using accepted commercial 
practices.

I have noticed underattenuation when pitching directly from the swollen yeast 
package vs. pitching with more yeast.  I brewed the same recipe on 
consecutive weekends.  I didn't plan ahead and pitched directly from the 
pouch on the first batch.  The second batch was fermented on the yeast cake 
from the first batch.  The second batch finished at least 10 points lower 
than the first batch

Someone asked about pitching these starters into the wort.  I pitch my 1 pint 
and 1 quart starters into the wort in their entirety (and yes, I add 1pint of 
wort to my 1 pint starter to get a 1 quart starter).  If I'm pitching a 
gallon of starter, I will let the yeast settle out, decant the liquid off, 
add a pint of wort to the yeast cake and make sure it's active before 
pitching that.  If I'm thinking ahead, I typically brew high gravity beers 
the same day I rack a batch into secondary so I can have the benefit of the 
yeast cake from the prior batch without going through the hassle of growing 
up another starter.

Keith MacNeal
Worcester, MA



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Date: Sat, 19 Feb 2000 11:59:50 -0500
From: Dan Listermann <72723.1707 at compuserve.com>
Subject: Airstone Carbonation

Aaron Perry (vspbcb at earthlink.net) writes about counterpressure filling a
keg that had been carbonated with an air stone:

<Last week or so I made a post in regards to using a counterphil on a keg
carbonated with a carbonation stone.  BAD MOVE!!!   I'm not sure on the
specifics of what went on, but the beer was some how pushed
backwards???  sort of a reverse loop???  The CO2 usually is pumped into
the headspace of the keg,  with the stone,  it bubbles up through the
beer.  I can't figure what's happening, all I can say is that it didn't
work.  I set it up and attempted bottling, failed, then bottled a
braggot ( Regularly force carbonated-no stone) without incident. The
braggot went so smoothly that I gave the stone carbonated brew a whirl
again......Same thing!!!>

I dont know, but it seems to me that he may have been trying to pass beer
up through the dip tube with the stone still attached.  This will not work
as the stone offers a lot of resistance to flow for a liquid.  This problem
would even slow a picnic faucet to almost uselessness.  To get the beer out
the stone will have to be removed.  

If he wants to leave carbonation stones in the keg after it is carbonated,
he should consider attaching the stone to the "in" tube and invert the keg
for the carbonation process.  This way the air stone will only pass gas, no
beer and the "out" tube would not be clogged.

Dan Listermann   dan at listermann.com   72723.1707 at compuserve.com


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Date: Sat, 19 Feb 2000 11:11:40 -0600
From: "MrWES" <killshot at enteract.com>
Subject: WATCH

Brian Wrote...
 
No.  The directions on the labels are for commercial use.  For
homebrewers we recommend 2 oz. of PBW per 5 gallons of solution.  Let me
explain the discrepency.  With cleaning and sanitizing chemicals, there
are three main factors, concentration, temperature and length of time of
exposure.  Basically, if one of these three factors is decreased for
whatever reason, another must be increased to obtain the desired
effect.  Commercial brewers are usually using PBW for CIPing a kettle or
fermenter and the actual exposure time is often reduced.  Therefore,
they make it up with a higher concentration.


 
I wrote...
 

Brian is actually referring to a formula in the sanitation industry 
called WATCH:


W =3D Water
A =3D Aggitation
T =3D Temperature
C =3D Chemical Consentration
H =3D Heat

Each represent 20% of a successful cleaning and/or sanitizing regemine. 
If one portion the formula is missing or reduced, you need to increase 
the other to make up for it. Sometimes it's by design. Another words, if 
commerical brewers engineer their CIP (Clean In Place) systems for a 
quicker (shorter) contact time -- as to reduce downtime of the 
equipment, they may increase consentration, aggitation, or introduce 
heat to make the chemical more effective.

Bill

P.S. Nice to see you posting Brian :)




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Date: Sat, 19 Feb 2000 13:57:37 -0500
From: "Stephen Alexander" <steve-alexander at worldnet.att.net>
Subject: high temperature wort settling

Joe Gibbens asks ..

>If the "hot break" gradually comes out of solution as the temperature
>drops, where is the line drawn between hot and cold break?

Generally hot break forms in the boil. You will continue to get additional
cold break all the way down to the freezing point.  It isn't a temp vs
solubility
issue since the particulate break is not in solution. The flocs are just
forming
big enough particles to sediment rather than stay in suspension.

 -S




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Date: Sat, 19 Feb 2000 13:17:28 -0500
From: "Stephen Alexander" <steve-alexander at worldnet.att.net>
Subject: contaminated yeast/Fusels/Yeast  (starter) Questions

Nathan Lansing writes ...

>Scott Laboratories will send you a "typical" analysis [...]
>Cooper's also publishes this information.

I'd like to commend ANY brewing yeast producer willing to release
such analyses.

>So what's the worry? Do you think large commercial breweies
>are working with 100% pure pitching yeast?

AB's microbiologic controls are legend.  They are certainly not tolerating
the levels of contamination you quoted for Danstar.

>They acid wash each pitching.

Wrong.  Acid washing is performed after several brewing cycles
by micros and small breweries and will cause abnormal growth patterns
afterwards.  Acid wash yeast must be regrown to a normal state, or at
least the resulting beer must be mixed with normal beer for QA reasons.
Acid washing does not eliminate wild yeast (perhaps the most pernicious
infection problem - difficult to ID or treat).  The big boys I suspect keep
separate pitching cultures from  plated out and recultured yeast.

>Even if you had a laboratory and picked a single cell and grew it in
>autoclaved flasks under sterile conditions, wouldn't you be pitching it
>into a rather unsterile fermenter?

Right. A well sanitized fermentor is only stop-gap, which is why most of
us can't repitch forever.

===
D.Burley writes ...

>George De Piro says that when you
>get high growth rate you always get
>high fusel alcohols and believes it
>is an absolute.  Not so.   As I
>understand it, If the supply
>of simple nitrogen from things other
>than amino acids is sufficient, then no
>amino acids will be deaminated
>and no fusel oils formed.

I can't agree at all.

The model originally developed by Ayrapaa 4 decades ago and
repeatedly verified since is that there are two mechanisms for fusel
creation.  The one Dave is apparently aware of is the Ehrlich mechanism
which goes back many decades further to 1906 (yes - it's the "magic bullet"
Ehrlich).  The other is a synthetic mechanism which is dependent in the
synthesized oxo-acid pool.   The Ehrlich mechanism is related to a large
consumed oxo-acid pool and certain carbo fermentation products control
the rate.  Both are fairly directly related to yeast growth rate.

If amino acid concentrations are high, then the synthetic mechanism is
almost halted.  If low, and nitrogen is available, and growth is occurring ,
then the synthetic mechanism is dominant.  Dave is wrong about this too.
The amino acid level is the controlling factor, not the nitrogen level.  If
both
the aminos and nitrogen are present, yeast selectively use the amino acids.

There are other fusel mechanism, such as the  reduction of proprianate
to n-propanol, and ones related to catabolism of odd-chain fatty acids.
These
may be factors under special circumstances.

Forcing yeast to use inorganic nitrogen to synthesize oxo-acids also
reportedly
has bad flavor consequences in beer.   Bottom line.  I don't have figures
which
separate out the relative contributions of the two major synthetic
mechanisms
of fusels, and this is probably very strain dependent.  The graphs I have
seem
show a very strong correlation between cell growth RATE and
fusel production RATE  - just as George de Piro said.

My experience is that worts low in amino acids (like bad kits)  can produce
horribly fusel-y beers.  Also yeast in barleywines often also produce
obnoxious levels of fusels because of the high amino acid levels and high
ethanol content.  Two different mechanism to the same bad result.

My advice to Dave is to retire his beloved half century old DeClerc to
the antiquarian book collection.  Even M&BS doesn't contain a modern
accounting of fusel production.

My advice to brewers is to choose a different yeast if fusels give you
problems.
The yeast strain is a major factor in fusels.  But try to keep the amino
acid level
appropriate (not too high or low) for the yeast growth required.  You can't
avoid
the growth, but you could slow the rate (ferment colder for example).

- --
One other related point.  It's largely the growth RATE rather than the total
amount of growth that matters most.  Relates to the concentrations of
oxo-acids in the case of fusels, and to other flavor effects too.  Note that
if we pitch REALLY big as in lager brewing, then 75% of the final yeast
cake is new growth, if you pitch really small, as from a smack-pack, then
maybe 99% of the final yeast is new growth. The difference in flavor is not
likely due to the difference of 75% vs 99% new yeast growth.  Adding an
extra 32% (100*(99/75 -1)) of off-product doesn't give the sort of
night-and-day differences that underpitching causes.

===
Jeremy J. Arntz asks ...

>I am interested in yeast "ranching". I've been reading archives issues of
>HBD about the culturing and freezing of yeast samples.

These are two different things.  For 'freezing' or cold storing a culture on
an agar plate you should not be overly concerned about concentration of
nutrients - as the growth is limited, surface and likely aerobic.
For starter wort you should be very concerned about growth conditions and
concentrations.

>1. What should the specific gravity of the "base" wort be?
>   I've read 1.040, but I also believe that I've read 1.020.

IMO 1.020 is fine when making up an agar plate for storage, but 1.030
or 1.040 is best for starter wort.  Higher than 1.050 slows growth and
know of brewers who won't repitch from even 1.055SG beer because the
yeast isn't so energetic after this workout.  Less than 1.030 and the sugars
will form a low limit to the amount of yeast growth.

>2. What recipe should be used for the wort?
>   Again I've read 2 Tablespoons of DME in a cup of boiling water.
>   What about hops?

Calculate the SG by weighing rather than volume measuring the DME.
Hops can have a MINOR antibacterial effect against a very few bacteria.
Not only is it not worth the trouble, but it can also mask the fact that you
do have infection problems in your starter media.  It also could mask the
off-flavors that you should be trying to smell and taste for when you
separate the starter media from your yeast. IMO you should avoid
hops in starters.  IF you have an infection problem with your starter
media the answer is to review and revise your sanitation procedures,
not add bandaids.

>3. I am also interested in how streaking for isolated colonies reduces or
>   eliminates mutations?

It gives you the ability to select a colony developed from a single cell.
If that
cell was a mutation, the culture you grow from it will show defects like a
sore thumb.  Often the surface plate colony will look odd to begin with.
Certain mutant, such as oxygen deficient mutations occur regularly at
high rates (0.5%!) and so avoiding these means choosing culturing
conditions that prefer normal growth - plating out won't help here.


>4. Does anyone know of a good book on yeast propagation the is in-depth and
>accurate,  yet is semi-easy to read? I am especially interested in storing
and
>quality control.

Rog Leistad has a nice little pamphlet for beginners, but the next
step from there is the professional lit.  Any university library should have
some books intended for undergrads - perhaps labs practices manuals,
that you should find very readable.  Tho' they will probably not be specific
to
yeast, and certainly not brewers yeast.

YKCK  http://oeonline.oeonline.com/~pbabcock/yckco/yckcotbl.html
has all of the materials you'll need and enough yeast cultures to keep
you busy.  The only 1stop shopping place I'm aware of for small orders.

 -S






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Date: Sat, 19 Feb 2000 14:43:41 -0500
From: "Alan Meeker" <ameeker at welchlink.welch.jhu.edu>
Subject: more pitching rate

Bret Morrow wrote in part:

> Yeast pitching rates that get taken as gosple on HBD are
> industrial-based.  The goals of industrial based brewing are different
> than my own.

Bret, I think it is important to realize that this is only partly true. This
is one of the things I was criticizing Pivo for - such black and white
statements almost never apply to such a complex enterprise as brewing.

We certainly share /some/ of  the same goals as any large-scale commercial
brewing outfit such as:

Consistency

Lack of off-flavors
    -from poor fermentation performance due to stressed yeast
    -from contaminating microbes getting a foothold
    -from autolyzed yeast

Complete and timely fermentation


All of these will be impacted to a significant degree by the yeast pitching
rate. Of course, there are constraints on the big boys that we homebrewers
aren't bound by - like the need to optimize throughput/turnaround time and
optimize the use of raw materials in order to  maximize profits. While these
play a big part in determining something like pitch rate for the commercial
guys they are still constrained by the quality factors I mentioned above.

Also, saying something like "low pitching rates are fine" glosses over a
number of important variables that could easily serve to negate such a
simplistic statement. Things like yeast strain differences, how healthy are
the pitching yeast? How well oxygenated were they during the growth of the
starter (ie - how well charged in sterols and UFAs are they)? How are their
glycogen levels? How well aerated is the wort they are going into? What is
the SG of the wort? How's the FAN? What temp will the ferment be conducted
at? What kind of beer are you trying to make? etc etc etc... All these
variables and more come into play making it virtually useless to make any
blanket statements regarding pitching rates.

The advice to experiment within the realm of your own system is certainly
good advice. I have done so and found that the closer I can get to
commercial rates the better the quality of my beer.

However, there are instances in which pitching rate may be a useful process
variable for adjusting the final flavor of the beer. George De Piro and
others have pointed out the case of Bavarian Weissens in which you can
adjust the resultant ester profile by adjusting pitch rate.

 -Alan Meeker
 Lazy Eight Brewery
 Baltimore, MD



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Date: Sat, 19 Feb 2000 15:09:54 -0400
From: Aaron Perry <vspbcb at earthlink.net>
Subject: contamination

Cocci or not!  Wyeast  hasn't failed me yet !!!!!!
Great brews!!!!



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