---

	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
		Digest Janitor: pbabcock at hbd.org


***************************************************************
        TODAY'S HOME BREW DIGEST BROUGHT TO YOU BY: 

                 Sponsor The Home Brew Digest!
     Visit http://www.hbd.org/sponsorhbd.shtml to learn how
			 
    Support those who support you! Visit our sponsor's site!
********** Also visit http://hbd.org/hbdsponsors.html *********

DONATE to the Home Brew Digest. Home Brew Digest, Inc. is a 
501(c)3 not-for-profit organization under IRS rules (see the
FAQ at http://hbd.org for details of this status). Donations
can be made by check to Home Brew Digest mailed to:

HBD Server Fund
PO Box 871309
Canton Township, MI 48187-6309

or by paypal to address serverfund@hbd.org. DONATIONS of $250 
or more will be provided with receipts. SPONSORSHIPS of any 
amount are considered paid advertisement, and may be deductible
under IRS rules as a business expense. Please consult with your 
tax professional, then see http://hbd.org for available 
sponsorship opportunities.
***************************************************************


Contents:
  yeast propgation (Rob Schlank)
  Re:  Should I repitch? (Stephen Jorgensen)
  Should I repitch? (Scott Birdwell)
  Helium ("Chad Stevens")
  more yeast perf ... pt 1 ("Steve.Alexander")
  more yeast perf ... pt 2 ("Steve.Alexander")
  Kalamazoo Stout (Tim Eitniear)
  2009 South Shore Brewoff - competition announcement ("jeff_ri")


* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*           The HBD Logo Store is now open!             *
*            http://www.hbd.org/store.html              *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*   Beer is our obsession and we're late for therapy!   *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * *

NOTE: With the economy as it is, the HBD is struggling to 
meet its meager operating expenses of approximately $3400
per year. If less than half of those currently directly
subscribed to the HBD sent in a mere $5.00, the HBD would
be able to easily meet its annual expenses, with room to 
spare for next year. Please consider it.

As always, donors and donations are publicly acknowledged
and accounted for on the HBD web page. THank you

 
Send articles for __publication_only__ to post@hbd.org

If your e-mail account is being deleted, please unsubscribe first!!

To SUBSCRIBE or UNSUBSCRIBE send an e-mail message with the word
  "subscribe" or "unsubscribe" to request@hbd.org FROM THE E-MAIL
  ACCOUNT YOU WISH TO HAVE SUBSCRIBED OR UNSUBSCRIBED!!!**
IF YOU HAVE SPAM-PROOFED your e-mail address, you cannot subscribe to
  the digest as we cannot reach you. We will not correct your address
  for the automation - that's your job.

HAVING TROUBLE posting, subscribing or unsusubscribing? See the HBD FAQ at
http://hbd.org.

LOOKING TO BUY OR SELL USED EQUIPMENT? Please do not post about it here. Go
instead to http://homebrewfleamarket.com and post a free ad there.

The HBD is a copyrighted document. The compilation is copyright 
  HBD.ORG. Individual postings are copyright by their authors. ASK 
  before reproducing and you'll rarely have trouble. Digest content 
  cannot be reproduced by any means for sale or profit.

More information is available by sending the word "info" to 
req@hbd.org or read the HBD FAQ at http://hbd.org.

JANITORs on duty: Pat Babcock (pbabcock at hbd dot org), Jason Henning,
                  and Spencer Thomas



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


Date: Tue, 17 Feb 2009 09:11:56 -0500
From: Rob Schlank <rschlank at comcast.net>
Subject: yeast propgation

Joshua WIlkins wrote, "The smack packs that Wyeast uses
contains nutrients and the sachet that you pop on the inside is the yeast
cells."

Not to nitpick, but this is incorrect.  The sachet contains the nutrients,
not the cells.  You can, if you wish, pitch the cells into a starter without
'smacking' the sachet.  This is per Dave Logsdon  at  Wyeast in an interview, I
believe from an old TBN show.  I have done this myslef several times, though
now I smack the pack just to get the nutrients into the starter as well.

- --
Rob Schlank


Return to table of contents


Date: Tue, 17 Feb 2009 09:35:17 -0600
From: Stephen Jorgensen <stephen at ultraemail.net>
Subject: Re:  Should I repitch?

      

	"I have an IPA in the secondary for about 10 weeks.  It looks clear and tastes 
	decent upon sampling."


In my experience there is no more disappointing result in home brewing 
than a bottle of sweet, flat beer.  Yes you should use fresh yeast to 
package your IPA but an entire envelope is not necessary.

I don't have the correct cells / ml numbers to hand but I am sure there 
are multitudes of brewers reading HBD that know them by heart.  I 
generally use about 1/10 the amount for bottling as I did when pitching 
the wort.  In the case of Danstar Nottingham (no affiliation) which is 
my bottling yeast of choice I use 2-3 g for a 6 gallon batch.  For an 
IPA I would go with 3.


Return to table of contents


Date: Tue, 17 Feb 2009 13:37:03 -0600
From: Scott Birdwell <defalcos at sbcglobal.net>
Subject: Should I repitch?

Regarding Tom Puskar's question, "Should I repitch. . ."

"For a number of reasons ranging from illness, work and family issues,  
I have
an IPA in the secondary for about 10 weeks.  It looks clear and tastes
decent upon sampling.

I'm hoping to bottle it (FINALLY) this coming week and wondered if I  
should
add some additional yeast for carbonation.  I keep a few envelopes of  
dry
yeast around and could proof one up and add it to the bottling  
bucket.  I
haven't checked the gravity in a few weeks but last check it was around
1.015 and hadn't changed for a while."

Tom,
    It's like chicken soup. . . it couldn't hurt!  Just rehydrate the  
dried yeast in some lukewarm water and mix it thoroughly into the beer  
just before/after you mix in your priming sugar.  You should have  
carbonated beer within a couple of weeks.  Good luck!

Scott Birdwell
DeFalco's  Home Wine & Beer Supplies
Houston TX


Return to table of contents


Date: Tue, 17 Feb 2009 14:35:49 -0800
From: "Chad Stevens" <zuvaruvi at cox.net>
Subject: Helium

Got my CO2 tank filled yesterday.  On the way out of the shop I saw a helium 
tank.  Brewers being mad scientists by default, I thought to myself, 
"wouldn't that be an interesting party trick, Helium 'carbonated' beer." 
Take a sip, then sing, "We represent, the lollipop guild...."

Anyone tried it?

Chad Stevens
QUAFF
San Diego
www.sdfair.com/beer 



Return to table of contents


Date: Tue, 17 Feb 2009 18:03:56 -0500
From: "Steve.Alexander" <steve-alexander at roadrunner.com>
Subject: more yeast perf ... pt 1

Uhoh - 8k bouncy bouncy

I've used imprecise language and now several ppl have posted their own 
(sometimes odd) views on terminology and we are making a mish-mash of 
this discussion.  In common use "ferment" merely means microbiological 
activity. I didn't really think we need/want to delve so deeply on this 
one but ....

According to Brock's "Biology of Microorganisms", a very widely used and 
highly regarded text we have ...  "Fermentation  - Catabolic reactions 
producing ATP in which organic compounds serve as both primary electron 
donors and ultimate electron acceptors and ATP is produced by 
substrate-level phosphorylation".   And, "Respiration - Catabolic 
reactions producing ATP, in which either organic or inorganic compounds 
are primary electron donors and organic or inorganic compounds are 
ultimate electron acceptors".   If you study the definitions carefully 
you will see that respiration is any ATP energy pathway, while 
fermentation additionally requires organic donors, organic acceptors and 
substrate-level phosphorylation (as opposed to oxidative phosphorylation 
pathway).   Brock divides catabolic pathways into "aerobic respiration" 
and "anaerobic respiration", and OBVIOUSLY he's not referring to the 
environment but the metabolism.

According to Brock's ... Fermentation IS a type of respiration !!!!
Aerobic/Anaerobic can and usually does refer to the metabolism NOT the 
environment.
 . so perhaps we all get a big fat F- for terminology.

Nester-Robert-Nester "Microbiology", and Stryker "Biochemistry"  says 
that respiration requires any inorganic electron acceptor.
Mathews-vanHolde*, *"Biochemistry",  says respiration requires oxygen as 
the electron acceptor.

===========
The two concepts we are trying to distinguish here are related to how 
the metabolic phosphorylation of ADP to ATP occurs, but thats awfully 
deep into the nuts & bolts.

In conventional brewery fermentation with Saccharomyces yeast (of 
course) none of the catabolic(energy producing) pathways use free 
oxygen.   Brewery yeast induce sugar or create these from enzymatic 
breakdown of sugar polymers.

First, each hexose sugar is converted to two pyruvates + 2 H2O + energy 
as a net +2 ATP. This is known as the Embden-Meyerhof-Parnas (EMP) 
pathway and is one of several glycolytic pathways.  The ATP is produced 
by substrate-level conversions of bisphosphoglycerate and 
phosphoenolpyruvate.

The pyruvate can readily, enzymatically be converted to lactate (as in 
your muscles) acetate+formate or acetaldehyde+CO2.  In yeast the 
pyruvate is converted to acetaldehyde+CO2 and the acetaldehyde is 
reduced (the organic electron acceptor) into ethanol.

The EMP pathway also converts 2 NAD+ to 2 NADH and this is a great 
energy store (1 NADH can be converted to 3 ATP with some oxygen) BUT to 
accomplish the redox balance all of the NADH must be used to reduce 
acetaldehyde to ethanol.  In anaerobic condition it is always necessary 
to use the NADH of glycolysis to reduce the pyruvate product.

No oxygen is required for this catabolic pathway, and the net energy 
yield is only 2 ATP per hexose.

- --
Under ABNORMAL conditions we can get brewing yeast to use another 
catabolic pathway using sugars.  The yeast induce sugars as before.  The 
EMP glycolytic pathway occurs too producing pyruvate and ATP as before. 
  The next pathway is the  "Citric Acid Cycle"(CAC) , aka Tri-Carboxylic 
Acid Cycle(TCA) and more formally as the Szent-Gyorgyi/Krebs cycle (note 
Szent-Gyorgyi is one guy).  The major plot is that the 3-carbon chain 
pyruvate is converted to 3 CO2 molecules by repeated decarboxylation.   
First the pyruvate is converted to AcetylCoA+CO2, then the Acetyl-CoA 
plus an oxalacetate(from...see below)  becomes  ketoglutate+CO2,  then 
the ketoglutarate becomes succinyl-CoA+CO2 and finally the succinyl is 
reverted to oxalacetate and added back at the start of the next cycle.

The CAC+Glycolysis results in net yield 38ATP of energy per hexose and 
only 4 of the ATPs of the total produced are by substrate-level 
phosphorylation, the rest by oxidative phosphorylation.
========

Heading out of the chem lab and back toward the brewery .....

There are some silly notions perpetrated and/or perpetuation by poorly 
researched HB books.  Brewery yeast under normal brewing conditions 
NEVER use the CAC cycle (almost never).   Not even when they are pitched 
into well oxygenated normal wort.  Now IF you use an open fermenter then 
after all the sugars are used up the yeast can oxidize ethanol back into 
aldehyde then convert to acetyl-CoA which can then enter the CAC cycle 
and yields a lots of energy.  The "back up the tree" process can also 
throw off some lactate and acetate.   It's unclear how rapidly this path 
can operate but distilleries use open fermentation and I've seen figures 
indicating that a few percent of the ethanol is used per 24 hours of 
extra delay.  I would imagine that oxygen is a limiting factor in those 
conditions.

If you can grow yeast with their metabolism using the CAC cycle, then 
there are some metabolic and environmental differences.  The yeast are 
constantly exposed to free oxygen (needed for the oxidative 
phosphorylation) and so they don't accumulate squalene (a precursor to 
sterol) but instead they contain a high level of sterol.   Similarly 
with ever present oxygen yeast can construct (mostly mono-) unsaturated 
fats and so these yeast have the best cell membranes around.  As the 
yeast hit a growth limitation then I would expect that they will store 
"storage carbohydrates" abnormally; glycogen accumulates in response to 
growth limitations, but also degrades in the presence of oxygen.  
Trehalose accumulates in response to a wide array of stresses including 
nutrient deficit.  So  pitching yeast that have finished in aerobic 
metabolism is probably nearly ideal except for glycogen, and that's 
probably not terribly important unless you plan to store the yeast (then 
an anaerobic final finish w/ a little sugar added might be best); and 
since these are high in UFA&Sterol so there is less need to aerate the wort.

Yeast in anaerobic conditions suppress the enzymes of the CAC cycles, 
and in aerobic conditions they suppress the creation of cytochomes that 
are involved in the electron transport for redox balance (far less is 
needed).   This is NOT a big deal unless you are the sort who gets 
ants-in-the-pants if a fermenter isn't bubbling in 20 minutes.

- --
(continued)




Return to table of contents


Date: Tue, 17 Feb 2009 18:04:25 -0500
From: "Steve.Alexander" <steve-alexander at roadrunner.com>
Subject: more yeast perf ... pt 2

(continued)

Kai T suggests ....


>> > > It might be that low gravity propagation isn't  
>> > > good either b/c the yeast may get uses to the lower alcohol/sugar  
>> > > concentration both of which are stress factors.   
>>     
No. High gravity is just a ion pump stressor (yeast must expend more
energy moving ions across cell membranes) and there is no way to
accumulate a tolerance to the added workload except to include more
sterol & UFA per cell to reduce "leakage". It's always best to
propagate yeast at 5-7P.

Joshua Wilkins mentions his experience with a commercial propagator but 
 .. this doesn't exactly hit the mark either. This sort of propagation 
is aimed at providing oxygen to yeast culture, such as a scintered stone 
would, but it is not aimed or creating conditions for aerobic metabolism 
(the CAC cycle).  There is nothing very expensive about scaling this 
down to HB level.

His other comments fall solidly into the "old brewers tales" category.  
That yeast develop resistance to ethanol and hops doesn't match anything 
I've ever read anywhere - and the fact is that all fermentation produces 
intracellular ethanol.  The "resistance" or more correctly high 
tolerance of high level is of extracellular ethanol is from several 
studies only related to cell membrane quality and the absence of the 
environmental stressors like excess CO2 in solution and the presence of 
several specific amino acids which reduce the osmotic stress effect.  
When repitching into a barleywine you can and should use sterol&UFA rich 
yeast propagated at ~5P.

The idea that you should walk yeast through the sugars they consume (the 
order glucose,fructose, maltose, maltotriose is common) before you plop 
them into fresh wort has absolutely no advantage.  The presence of 
glucose inhibits the transport of the maltose & maltotriose ; maltose 
inhibits the maltotriose and so on  ... and the enzymes for transport 
and hydrolysis simple don't last long enough to make any difference at 
all.  There may be a slight advantage in propagating yeast on glucose 
since it's the first sugar they'll get at pitching, , but frankly it's 
pretty far down the "don't care" list.   So long as the yeast is 
reproducing correctly and has the necessary nutrients, then they carry 
all the genetic machinery to produce (and alternatively inhibit) the 
right enzymes for their *current* conditions and it only takes minutes 
for them to make a transition if healthy.

*IF* (this is a huge if) you could force yeast into using the CAC cycle 
they would produce roughly 10X the biomass per unit sugar so wort would 
be too deficient in nutrients to be useful.   Adding nitrogen can 
alleviate the nitrogen deficit *BUT* I've recently read that (low) 
nitrogen plays a huge role in keeping yeast in aerobic-respiration 
metabolism.  If nitrogen is low then respiration is preferred (low 
nitrogen limits sugar transport), but the low nitrogen also inhibits 
growth rate.  So you really need to carefully feed both sugar and 
nitrogen.  Boulton & Quain "Brewing Yeast and Fermentation", suggest 
that the only way to get yeast to respire is to slowly feed sugar in a 
very low nitrogen environment or to use a chemostats under carbon 
(sugar) limitation.  A chemostat is a bit of lab gear that allows one to 
adjust the input rates into fermenter (with corresponding output) so 
that the vessel contains a stable culture.  It's not useful for biomass 
creation.  There are about 3 dozen well know required yeast nutrients 
aside from nitrogen and a carbon source(sugar ...) and these won't come 
cheap.  Urea and a good yeast nutrient are a start but what exactly 
provides biotin and pantothenic acid and enzyme cofactors and in what 
proportion ?

The only other CAC approach that makes sense is to use a substrate than 
cannot undergo glycolysis - so feed your yeast pyruvate or lactate or 
ethanol, xylitol or certain glycosides and let then run it thru the CAC 
cycle.  These are some so called "oxidative substrates", but the trouble 
is that aside from pyruvate, which yeast can use which substrate is hit 
or miss (The UK NCYC has very incomplete tables for their yeasts).   
Then we have the question of how fast can yeast really use oxidative 
substrates.  This may make this approach even more impractical; I 
believe that most can use ethanol, but the rate may be too slow to 
provide a decent propagation method.

Trying to grow yeast with CAC metabolism is an interesting hack, but 
ultimately costly and difficult.   I might feel differently if sugar was 
vastly expensive or else if pyruvate and other nutrients very cheap; but 
just the opposite is true.  It may have a place in producing yeast for 
freeze-dried storage, but that's a special application I don't need to 
practice.  If you learn to do this cheaply and effectively please drop a 
note, b/c it would be a great propagation technique.

The only really practical approach I see here is that if you bump oxygen 
into a conventional wort starter (say on a stir plate or with a stone) 
then your yeast will still be well supplied with UFA and sterols and 
you'll have the happy co-incidence that wort has about the right mix of 
sugar and nutrients to grow yeast using glycolysis only. 

As a very relevant aside, Boulton pioneered the "yeast oxygenator" 
method used commercially as Bass Brewers Limited.  They take a yeast 
slurry, presumably from a finished batch, and add just a bit of 3P wort, 
then the add continuous oxygen over a period of several hours.  They 
continuously measure the yeast oxygen uptake rate.   In about 3 hours 
the oxygen uptake rate peaks then it drops to a low figure after another 
3-4 hours.  At that point the yeast have degraded their glycogen store 
and produced all the sterol possible.  This is pitched directly into 
UNoxygenated wort in fermenter.   They give figures showing the beer 
attenuation rate is superior and far more consistent than wort 
oxygenation.  Also the there is no significant difference in esters or 
other flavor active yeast by-products.

Yeah - by all means get a lot of oxygen into the starter, and less into 
the wort !  But there isn't any practical gain to pushing the metabolism 
to oxidative phosphorylation on the HB scale.

 -S




Return to table of contents


Date: Tue, 17 Feb 2009 20:17:10 -0600
From: Tim Eitniear <timeitniear at sbcglobal.net>
Subject: Kalamazoo Stout

Hi,
    Trying to clone this lovely beer.  Found something in the archives from
2002 and I have the zymurgy articles from 2003.  Any one have any
suggestions or have found a AG solution to this beer?

Tim
- -- 
http://nottawaseppibrewing.wordpress.com
A guy walks into a pub with a lump of asphalt on His shoulder, He says to
the bar man give me a pint and one for the road.




Return to table of contents


Date: Tue, 17 Feb 2009 22:10:38 -0500
From: "jeff_ri" <jeff_ri at cox.net>
Subject: 2009 South Shore Brewoff - competition announcement

The 2009 South Shore Brewoff is the 14th annual homebrew competition 
organized by the South Shore Brew Club. The competition is organized to 
provide entrants with a high level of evaluation and valuable feedback on 
their brewing efforts. Whether you are a novice or a seasoned brewer, we 
welcome your participation.

The competition will be held in Mansfield, MA on April 18th, 2009. The 
entry deadline is April 3rd, 2009.

All entry information is on the club webpage at: 
http://www.southshorebrewclub.org/

Geoffrey McNally (judge coordinator)
Kevin Farrell (competition organizer)




Return to table of contents

---