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


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Contents:
  Volumes of CO2 ("Spencer W. Thomas")
  re: Serial brewing ("steve.alexander")
  sour bottled beer II (Matt)
  Cleaning between brews ("Ant Hayes")
  Re: CO2 Quantity (Fred L Johnson)


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JANITORs on duty: Pat Babcock (pbabcock at hbd dot org), Jason Henning,
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Date: Wed, 07 Nov 2007 09:15:01 -0500
From: "Spencer W. Thomas" <hbd at spencerwthomas.com>
Subject: Volumes of CO2

Generally, the term "volumes of CO2" is understood to be the amount of
CO2 that has the given volume at a standard temperature and pressure
(STP).  In scientific applications, STP is 0C and 1bar, so I'll go with
those.

1 mole of CO2 weighs (approximately) 44 grams, and measures
(approximately) 22 liters at STP.  Thus, a liter bottle of beer with 2
volumes of CO2 would contain 4 grams of CO2.  A 12 oz bottle (336ml) at
2 volumes would contain about 1.3 grams of CO2.

If you want to take measurements at 20C, deflate the numbers above by
about 7%.

=Spencer in Ann Arbor




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Date: Wed, 07 Nov 2007 10:25:51 -0500
From: "steve.alexander" <-s at roadrunner.com>
Subject: re: Serial brewing

Christopher Burian says ...

>> > I'm planning a serial brew (Belgian single, dubbel, trippel--reusing
>> > yeast at each step).
> However, repitching a trippel onto an exhausted dubbel yeast
> could have a less optimal outcome.  I would do a single each
> time as a starter for the dubbel and also the trippel.
>
> It's helpful to have fresh, healthy yeast to ferment a high
> gravity, highly attenuated beer like a trippel, and the only
> way to get fresh yeast is through reproduction.
and this is the fundamental problem with this plan.

Al Korzonas (whatever became of AlK?) had a rule of thumb that
you never re-use a yeast cake that was previously used on 15P
or higher gravity wort.  He was not being overly conservative.
Particularly, as Chris notes, when attempting serial hi-grav
beers.

You might get away with dubbel->single->trippel yeast re-use,
but personally I'd re-work the yeast before the trippel to make
sure it's vigorous and in very good shape.
- --

Cleaning many not be necessary, but sadly homebrew sanitation
methods are a lot like driving a car by looking out the rear view
mirror; you never know if your sanitation is "good enough" except
in hindsight, and your major "learning events" are disasters.

All HB is marginally infected, so anything that encourages this
trend is flirting with disaster.  Now if you are willing to plate
out fermenter samples on a differential medium and track the
infection level - you get a pass; otherwise clean.

 -S




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Date: Wed, 7 Nov 2007 07:43:19 -0800 (PST)
From: Matt <baumssl27 at yahoo.com>
Subject: sour bottled beer II

Since every bottle develops sourness, and since you're not cleaning the
bottles with anything sour, it appears that the full batches are
getting infected.

As I'm sure you know, NaOH and peracetic acid is a pretty well
established cleaning/sanitizing regimen.  I can't help you with the
contact time and concentrations of the peracetic, but I'm sure it can
be readily looked up on the web if you haven't already.

Do you clean your counterflow chiller by recirculating these chemicals
through it using a pump?  What kind of fittings do you have on the end
of the chiller (how are the hoses attached)?  And how are the hoses
cleaned and what are they made of?

A very useful test is the Wort Stability Test.  A protocol for this
test is available on the Brewing Science Institute website, but
basically you capture wort coming out of your chiller in a sterile
container and close it.  Something you can seal without fear of
dangerous explosion (such as a plastic screw top test tube) is ideal,
because it allows any gases produced by the infection to build up.  You
wait and see how long it takes to get infected (as evidenced by
cloudiness, a ring at wort/air interface, lots of escaping gas when you
unseal the tube, etc).  You are hoping to get to 3 days at room temp.

If you don't want to risk another full batch, just do a mini batch with
a gallon of water and a pound of extract.

This should determine whether the infection occurs before or after the
beer leaves the chiller.  Hope this helps,

Matt









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Date: Wed, 7 Nov 2007 21:54:57 -0000
From: "Ant Hayes" <anthayes at btinternet.com>
Subject: Cleaning between brews

AJ wrote, "Do AB and SABMiller clean between brews? I think they probably
do."

Don't know about AB but SABMiller run the cleanest breweries I have ever
seen (and I have visited a few). In fact their maltings are clean, their
workshops are clean, and their head office is clean. In short they are clean
freaks.

Ant Hayes
Hildenborough, Kent



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Date: Wed, 7 Nov 2007 18:46:15 -0500
From: Fred L Johnson <FLJohnson52 at nc.rr.com>
Subject: Re: CO2 Quantity

H. Dowda asked:

> OK, for the physics mavens, if a liter of a fluid (say
> beer) contains 2 vol of CO2 how many grams of CO2 are
> dissolved given a temp of 20C and a head space of less
> than 5% of container volume (closed 1050ml container)?
>  When we say vol of CO2 greater than 1.0 does that
> greater volume contain the assumed 1.0 vol at standard conditions.

I think the calculation goes something like this:

Because H. Dowda set the volume of CO2 dissolved in the liquid at a  
value of 2, values for temperature and pressure are not needed for   
the calculation. And head space volume is only needed to calculate  
the volume of liquid in the container.

Assuming a 1050 mL container that is 95% full--H. Dowda indicated   
that the container was more than 95% full--the volume of liquid in   
the container would be 997.5 mL. "Two volumes of CO2" means the mass  
of CO2 which would occupy two times the volume of the liquid if the  
gas were at standard temperature and pressure. Thus the "volumes" of   
CO2 dissolved in the liquid is: 2 x 997.5 mL=1995 mL CO2 dissolved in  
the liquid. One mole of an ideal gas (which includes CO2) occupies  
approximately 22.4 liters at standard temperature and pressure, so  
1.995 L CO2 / 22.4 L CO2/mole CO2 = 0.0891 moles CO2. CO2 has a  
molecular weight of 44, so 0.0891 moles CO2 has a mass of 3.91 g, the  
mass of CO2 dissolved in the liquid.

Fred L Johnson
Apex, North Carolina, USA


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