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


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Contents:
  Re: Yeast Performance / Aerobic propagation (bill keiser)
  Re: Yeast Performance / Aerobic propagation (Fred L Johnson)
  Low Alcohol Big Beers (Rick) Theiner" <rickdude@tds.net>
  aerobic growth is not respiration (Matt)
  Professional Brewing Course in Munich, Germany ("Lemcke Keith")


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Date: Thu, 12 Feb 2009 23:51:46 -0500
From: bill keiser <bk2 at sharpstick.org>
Subject: Re: Yeast Performance / Aerobic propagation

 Do you have any ballpark recommendations on how long it would take to 
attain 100% saturation using a surplus medical O2 concentrator and an 
aquarium airstone?  (that I just happen to have)
bill keiser

> As for aeration, I say aerate the wort until it is 100% saturated then pitch
> the yeast. No more is needed for both the starter and the production
> fermentor. But I do support the use of stir plates for starters mainly to
> keep the yeast from settling.
>
> I tried to keep this basic, but if anyone wants to get into the details
> feel free to ask and I can explain from there.
>
> Josh Wilkins
>
>   




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Date: Fri, 13 Feb 2009 07:29:43 -0500
From: Fred L Johnson <FLJohnson52 at nc.rr.com>
Subject: Re: Yeast Performance / Aerobic propagation

Joshua:

I appreciate your interest in the yeast propagation topic. I think we  
need details to consider the issues you raise.

Do you happen to know how Wyeast and White labs propagate the  
pitchable quantities of yeast they send to breweries intended to be  
pitched directly into their production batches. I'd venture to say  
that the propagation is not customized based on the water profile and  
nutrients in the batch of wort at the brewery. I also question  
whether the yeast are in their exponential phase of growth during  
shipment. I would think that that practice would be a potentially  
explosive situation. Are the yeast not in a more stationary phase  
when they are shipped?

I also doubt that hops are even included in the propagation. To what  
part(s) of "hops" must the yeast produce "resistance"? And exactly  
which genes must the yeast activate to "resist" hops that you say is  
important in the propagation of yeast prior to pitching?

Lastly, can you confirm that the method that Wyeast and White Labs  
uses to propagate the yeast destined for pitching directly into a  
production batch at a brewery is by stepping up in a standard fashion?

Fred L Johnson
Apex, North Carolina, USA



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Date: Fri, 13 Feb 2009 8:32:54 -0600
From: "Eric (Rick) Theiner" <rickdude at tds.net>
Subject: Low Alcohol Big Beers

Hail Brewmeisters,

My preferred brews are big on flavor, body, hops, etc.  
Thus I often brew IPA's and similar, but I would really 
rather not have to deal with the typically accompanying 
high level of ethanol.  If I sit down for 3 or 4 over the 
course of a few hours, I'd rather not be intoxicated at the 
end of the evening.

I have been thinking about playing around with high dextrine 
malts, but before I started down that road, I thought I'd ask 
if anyone on this list has done something along those lines...

And if not, what are your general thoughts on getting to my 
goal of a really big, but low alcohol beer?

Rick Theiner


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Date: Fri, 13 Feb 2009 07:28:23 -0800 (PST)
From: Matt <baumssl27 at yahoo.com>
Subject: aerobic growth is not respiration

AEROBIC in this discussion means "in the presence of oxygen."

FERMENTATION refers to a specific biological pathway by which
yeast metabolize wort sugars.  This can be done whether oxygen
is present ("aerobically") or not ("anaerobically").

RESPIRATION refers to a different biological pathway by which
yeast metabolize wort sugars.  This can only be done
aerobically.  (Any exceptions to that statement are probably
unrelated to brewing practice).

*When oxygen is present, yeast may metabolize sugar by either
FERMENTATION or RESPIRATION, depending on the Crabtree effect,
etc.  But either way the conditions are still AEROBIC.*

I think the folks who have posted on yeast propagation would
agree with me on these things (am I wrong?).  But for whatever
reason, some people are occasionally speaking as if respiration
and aerobic growth are the same thing, and using the terms
interchangably.  Perhaps this is just a convenient mental
shorthand, but it's frustrating to decipher the intent of
what's being said, and no doubt extremely confusing for those
who aren't familiar with the topic.




      


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Date: Fri, 13 Feb 2009 12:43:15 -0500
From: "Lemcke Keith" <klemcke at siebelinstitute.com>
Subject: Professional Brewing Course in Munich, Germany

Greetings from Chicago!
 
With the economy being what it is, there are a lot of people from
homebrew backgrounds that are inquiring about brewing courses towards
building a career as a professional brewer. If you are interested in
making the jump into professional brewing, you should check out our
2-week World Brewing Academy Concise Course starting May 4th in Munich,
Germany. This is an English-language intermediate-level course, and the
Concise Course in both the campus & web-based versions have become our
most popular offering for homebrewers looking to "go pro". If you want
more information on our courses, you can see the full course listing on
the web at http://www.siebelinstitute.com/course_desc/ , and if you have
any questions about building a career in brewing, please don't hesitate
to ask them by e-mail at klemcke at siebelinstitute.com . 
 
Keith Lemcke
Vice-President
Siebel Institute of Technology
World Brewing Academy
 



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