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


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Contents:
  FOY, 05- Oxygenation ("Rob Moline")
  FOY, 05-Mead-Schramm ("Rob Moline")
  Question about Dextine malt AND ROD's TRAVELS ("Rod Prather")
  FOY (2005): dry yeast/liquid yeast ("Peter A. Ensminger")
  David Edge:  Vital Dyes ("Shawn E. Lupold, Ph.D.")
  Fortnight Of Yeast, 2005 (Matt)
  Special B ("Rob Moline")


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*   Fortnight of Yeast 2005 - 10 July through 24 July   *
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Date: Tue, 19 Jul 2005 22:05:16 -0500
From: "Rob Moline" <jethrogump at mchsi.com>
Subject: FOY, 05- Oxygenation

Subject: Fortnight Of Yeast, 2005
From: Matt <baumssl27 at yahoo.com>

Question: Can you please comment on the strategy of trying to
aerate/oxygenate the yeast while they are in a STARTER rather than
aerating the wort itself.  (Please let me abuse the language and science
a bit and just say that yeast need "a big swallow of oxygen" before they
ferment beer.)  I understand that this is exactly your strategy in the
production of dry yeast--i.e. dry yeast can be pitched into unaerated
wort because they have already taken their big swallow of oxygen.  How
feasible is it for a homebrewer to grow up a starter in similar fashion?
Is continuous aeration of the starter required?  A stir plate?  If I
have no stir plate, and no gas transfer equipment of any kind, is there
a practical procedure I can follow to grow yeast whose oxygen
requirements are already met?  Letting air into the starter jug and
shaking it, repeating this over several days, etc?  Any temperature
dependency?  Any minerals or nutrients I can add to the starter to
increase the yeast's efficiency at storing up oxygen-related compounds?
Thank you for sharing your expertise.

Clayton: Yeast need a trace amount of oxygen in an anaerobic
fermentation such as brewing to produce lipids in the cell wall. With
out O2 the cell cannot metabolize the squalene to the next step which is
a lipid.  The lipids make the cell wall elastic and fluid. This allows
the mother cell to produce babies, buds, in the early part of the
fermentation and keeps the cell wall fluid as the alcohol level
increases. With out lipids the cell wall becomes leathery and prevents
bud from being formed at the beginning of the fermentation and slows
down the sugar from transporting into the cell and prevents the alcohol
from transporting out of the cell near the end of the fermentation. The
alcohol level builds up inside the cell and becomes toxic then deadly.

Lallemand packs the maximum amount of lipids into the cell wall that is
possible during the aerobic production of the yeast at the factory. When
you inoculate this yeast into a starter or into the ferm, the yeast can
double about three time before it runs out of lipids and the growth will
stop. There is about 5% lipids in the dry yeast. At each doubling it
will split the lipids with out making more lipids (no O2).  The first
split leaves 2.5% for each daughter cell. The second split leaves 1.25%
for each daughter cell.  The next split leaves 0.63%. This is the low
level that stops yeast multiplication. Unless you add O2 the
reproduction will stop.

When you produce 3-5% alcohol beer this is no problem.  It is when you
produce higher alcohol beer or inoculate at a lower rate, that you need
to add O2 to produce more yeast and for alcohol tolerance near the end
of fermentation. You definitely need added O2 when you reuse the yeast
for the next inoculum.

If you prepare a starter culture you will need added O2. in the starter
and perhaps in the main mash as a precaution. You will need to follow
the precautions as mentioned above.  If the mash is designed to produce
3-5% alcohol you may not need added O2.  Brewing above that needs added
O2.

Regarding you comment about growing your own yeast that will not need
added O2 in the fermenter; The Lallemand yeast factory grows yeast under
a different metabolic pathway than you will have in your starter
culture. We feed the media to the aerobic fermentation at a rate that
will keep the sugar levels below 0.2% at all times to maintain the
Pasteur Effect. This builds cell mass with minimum to no alcohol
production.  As the sugar level rises above 0.2% the Crabtree Effect
begins and no matter how much air you feed the fermentation, alcohol +
CO2 are the main by-products. Your starter culture will have a much
higher level of sugar. You will produce some cell mass but mostly
alcohol and CO2 no matter how much air you add by stirrer or bubbles.

I will bow to Dr. Tobias to reply regarding the preparing a starter
yeast with enough O2 to inoculate without further aeration. Tobias
routinely prepares starter cultures for his research projects.  


Clayton Cone

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Date: Tue, 19 Jul 2005 23:47:17 -0500
From: "Rob Moline" <jethrogump at mchsi.com>
Subject: FOY, 05-Mead-Schramm

 Ken/Jean Schramm <schramk at mail.resa.net>
Subject: Fortnight of Yeast:

Rob;

My questions revolve around mead fermentation.  Q's for the panel:

What is the ideal timing for nutrient additions for mead fermentations?

Clayton: 
Yeast prefer that the nutrients be added in increments over the first
1/3 of the fermentation. When all of the nutrients are added only at the
beginning a large cell mass is produced with each cell having a low
protein content. This low protein content makes it difficult to complete
the fermentation and withstand the alcohol toxicity near the end. Adding
the nutrients, primarily Nitrogen, in encrements results in less, but
adequate, yeast growth with each cell having a larger amount of protein.
High protein yeast ferment faster and with stand alcohol toxicity better
than low protein yeast. 

Yeast sugar transport systems that bring the sugar into the cell at a
prescribed rate, contain nitrogen.  Some of their half life span is
about two hours, so new transport enzymes must be generated constantly.
This requires a fresh source of available nitrogen.

Yeast require a steady source of nitrogen through out the growth phase
to produce DNA, RNA, amino acids, proteins and other cell components. If
the sulfur containing amino acid skeleton is not available to receive
the H2S as the yeast produces it, the yeast will expel it out of the
cell resulting in rotten egg odor.

Just as a point of interest, yeast produce 30+ times as much alcohol in
he growth phase as it does in the stationary phase. So be nice to the
yeast while it is growingand keep it growing as long as possible.


How do deficiencies of specific amino acids of wine and mead musts
contribute to the production of higher alcohols?  The two approaches to
their production I have seen in print are oxidative deamination and the
carbohydrate route.  Could you provide some input on which one is
correct, and how it proceeds?

Clayton: 
Both routes are used by the yeast. 
1.In a amino acid rich or sufficient environment, the yeast takes the
catabolic or Ehrlich route to strip the amino acid of its NH3 to use for
its own building blocks.  The remainder of the amino acid produces a one
carbon less higher alcohol. 
2. In an amino acid deficiency environment, the yeast will use the
anabolic biosynthesis route and produce the alpha-keto acid from glucose
then on to a higher alcohol.

Example: Catabolic or Ehrlich route -- Valine to alpha-keto acid to
Isobutanol.
         Anabolic route --- glucose to alpha keto acid to Isobutanol. 

         The above are over simplifications of what really takes place
and brings into question the exact Ehrlich    
         pathway.   


The four higher alcohols that I have seen presented that account for off
flavors in beer and wine are n-propanol, isoamyl alcohol, active amyl
alcohol, and isobutanol.  Are these the culprits in mead?

Clayton:
The four higher alcohols that you mentioned are present in all fermented
beverages and are an important part of their flavor and aroma profile. A
full bodied ale can handle more than a lager. A rich red wine requires
and perhaps masks more than a light white wine. A metheglin requires
more of these alcohols than traditional mead before they become an off
flavor. The secret is having them there in the right amount. 



Do you feel it is possible to conduct a .100 point SG fermentation of
mead must with a FAN content of 20-40 ppm and no nutrient addition
without the production of off flavors and higher alcohols?  Which yeast
strains might favor nutrient free fermentations, if any? (I am not a
believer in this option, but I am asking on behalf of some I know who
are.)

Clayton:
I wish that I had a good answer for you from actual experimental data
but I don't. .100 SG is about 26% sugar.  This alone would require
additional yeast and nutrients to complete the fermentation. Before
nutrients requirements were understood and added, mead makers were
satisfied to have fermentations that lasted 6 to 18 months. If I had to
make a guess as to what strain of yeast might work under those
conditions I would try Uvaferm 43 or Lalvin EC-1118. Both tend to be
neutral in ester formation and have low Nitrogen requirements and are
strong fermenters. I would try it on a very small amount. Double the
amount of yeast inoculum and rehydrate the yeast in the presence of
Go-Ferm.  Give it plenty of air the first 72 hours and watch the pH
during the first 12 to 24 hours.  Do not let the pH drop below 3.0.  Add
potassium carbonate if necessary. Let me know your results.


Thanks,
Ken Schramm

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Date: Tue, 19 Jul 2005 21:58:29 -0700
From: "Rod Prather" <rodpr at comcast.net>
Subject: Question about Dextine malt AND ROD's TRAVELS

Could someone explain the purpose of Dextrine Malt in a grain bill?

ROD's TRAVELS.

Recent Impressive Beers.

Unibroue Ephemere9 , Carolus Grand Cru9,
Widmer's Wheat.8  Chechvar 8(Very nice pils, Budweiser it isn't)

Recent Brew Pubs.

BJ's.  Ontario Ca.

Rising corporate brewpup chain.  Great atmosphere,   Damned good beers.  Had
a 7 glass tester.   The Kolsch is OK but it's not a real Kolsch, no lagering
and a bit of aldehyde. The Wheat was quite nice but a bit restrained.
Their almost perfect Pale Ale and the refreshing 5 grain Amber Ale are both
delights.  The Stout is confusing.  You are lead to believe it is a Russian
but it seems to be a compromise between an Irish, Russian and a Sweet Stout.
Slightly sweet with a distinct mouthfeel.  None of the lightness I expect
from Russian Stout.   Overall, a very nice range of beers.  Each of their
beers are distiguishable and have distincive flavors and hoppings make their
tester a great time.   .

OH!  The food looked good, too.



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Date: Wed, 20 Jul 2005 01:00:51 -0400
From: "Peter A. Ensminger" <ensmingr at twcny.rr.com>
Subject: FOY (2005): dry yeast/liquid yeast

FOY: 2005: Question:

For a homebrewer, dry yeast is much more convenient than liquid yeast. 
There are numerous strains of dry brewer's yeast that give very nice 
results for certain beer styles. However, the variety of dry brewer's 
yeast seems very limited. I would like to see dry satchels of yeast for 
making German Weizenbier (like Wyeast 3068), Belgian beers (like Wyeast 
1214 etc), and a better selection of dry yeasts for lagers. Can we 
expect to see a better selection of dry yeasts in the future? What are 
the technical problems that prevent development of a greater variety of 
dry brewer's yeast?

Sincerely,
Peter A. Ensminger
Syracuse, NY



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Date: Wed, 20 Jul 2005 09:22:27 -0400
From: "Shawn E. Lupold, Ph.D." <slupold at jhmi.edu>
Subject: David Edge:  Vital Dyes


David Edge wrote about Methylene Blue staining for yeast viability.  We
regularly use these techniques in mammalian cell culture.  We use Trypan
Blue, which is cheap and can be bought pre-mixed by credit card from
most lab supply companies (try InVitrogen ($11/100ml) or Sigma-Aldrich).
Buy the pre-mixed stuff...unless you want to turn your house blue.  In
the lab, I've used it for up to a year.  When it gets old the blue dye
congregates and gives a "speckled" background, but it still sufficiently
differentiates live from dead. 100 mls should last you a long, long
time.

I've never tried it on my yeast though.  I quickly look in the
microscope to ensure there is no bacterial contamination and to roughly
gauge health/viability by morphology (i.e.- shape and presence of
budding).  

Shawn

 



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Date: Wed, 20 Jul 2005 09:03:47 -0700 (PDT)
From: Matt <baumssl27 at yahoo.com>
Subject: Fortnight Of Yeast, 2005

In today's response on the question of whether there are more or less
"beer yeasts" these days, Dr. Cone mentioned that many yeasts currently
considered to be "wine yeasts" may produce excellent beer.

In his book "Farmhouse Ales," Phil Markowski reports that it is
speculated that the primary Dupont strain descends from red wine yeast.
 He also reports that fermentation at Dupont is similar to red wine
fermentation in many ways (temperature, duration, philosophy).  So
experimenting with wine yeasts is something I've been thinking about a
bit.

Can you elaborate on this?  Are there specific strains marketed by your
company that would be good candidates for experimentation?  Are there
any "red flags" or "green lights" that one should look for in
commercial descriptions of wine yeasts, when trying to identify strains
for experimenting?  Is it likely that most wine yeasts will lead to
estery, Belgian-style flavors?  Finally, are there specific wine yeasts
you know of that give brettanomyces-like leathery flavors, but in a
more controlled or predictable way than a pure brett culture would?

I greatly appreciate any guidance you can give.  Thanks,

Matt



		


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Date: Wed, 20 Jul 2005 21:24:36 -0500
From: "Rob Moline" <jethrogump at mchsi.com>
Subject: Special B

From: "BILL KUNKA" <wkunka at vianet.ca>
Subject: Subsitution for Special B malt?

Special B is malted by Dingemans, distributed by Cargill.
http://www.specialtymalts.com/dingemans/descriptions.html

Cheers!
Gump

"The More I Know About Beer, The More I Realize I Need To Know More About
Beer!"
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