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HOMEBREW Digest #4402
HOMEBREW Digest #4402 Mon 17 November 2003
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
Digest Janitor: janitor@hbd.org
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Contents:
Plastic vs. glass FG/Congrats to Pacific Gravity ("Chad Stevens")
Non-digest version? ("Greg 'groggy' Lehey")
Re: Refractometer specific gravity conversion ("Greg 'groggy' Lehey")
re: Refractometers (Michael Owings)
slightly OT- sparkling wine (Mike Ward)
link of the week - Nov 15, 2003 (Bob Devine)
RE: origin of Hops (Don Van Valkenburg)
RE: bottle washer ("Jim Yeagley")
cloudy beer with Wyeast 1028 ("Dave Burley")
brewing habits (Darrell.Leavitt)
Corny keg cleaning ("Jeremy Lenzendorf")
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Date: Fri, 14 Nov 2003 20:24:16 -0800
From: "Chad Stevens" <zuvaruvi at cox.net>
Subject: Plastic vs. glass FG/Congrats to Pacific Gravity
Recently someone posted they observed a consistent 2 point disparity between
side by side glass and plastic fermentations. I had noted the same 2 point
difference on a couple of glass/plastic (I've only done a couple) ferments
but had disregarded the phenomenon as anomolous. I have had the same (or
greater) disperity in side by side glass/glass and plastic/plastic
fermentations. What's interesting is that, while the gravities at the end
of primary may diverge, they always seem to converge by the end of
secondary.
For example: side by side five gallons per pale of the same batch, 1.076 OG,
WLP 510 Bastogne yeast, intentionally oxygenated one pale, no o2 for the
other. After 14 days o2 pale was 1.024, no o2 pale was 1.032 (even more
robust effect than I anticipated). After 14 days in secondary, both halves
of the batch were at 1.022 FG. No major differences in ester profile noted
by the way.
Could it be that his plastic ferments received better oxygenation than his
glass ferments?
Steve Alexander and I have had some offline chat regarding this and Steve's
(typically) exhaustive input follows. My assumption was that, because yeast
can pump out some heat and because plastic is marginally less thermally
conductive than glass, the plastic ferments run warmer and as a result
attenuate slightly more.
I'm not certain Steve's number crunching bears this out. Has anyone taken
temps on side by side identical glass/plastic ferments?
What do y'all think?
Chad Stevens
QUAFF
San Diego
P.S. Congrats to Pacific Gravity for taking QUAFF's title as California
Homebrew Club of the Year! Well deserved.
- -----------------------
Steve's stuff:
In fermenting 1.050 wort how much heat is generated ...
Let's assume the wort ferments to 73% apparent attenuation. This translates
to approximately [0.81 * 73] 59%. The rule of 81% is just an
approximation and the real value for a mostly anaerobic fermentation will be
pretty close to this.
1/ 59% of the extract was fermented or used as yeast biomass.
1.050 wort has a Plato of [ (258-(205*SG-1)) * (SG-1) ] or 12.4P. So the
common brewing myth is that the extract has the same properties as a sucrose
solution (Plato studied sucrose sol'ns).
So 12.4% of the WORT mass is extract. 1Liter of water at 20C weighs 998.23gm
and the wort weighs 1.050 times as much or 1048.1gm/L. This means that the
wort has [0.124*1048.1] or 130gm/L of extract
2/ This wort has 130gm/L of extract.
3/ (fm 1/ & 2/) the yeast uses 76.7gm/L of extract.
Balling's empirical formula is that anaerobic fermentation involves:
200gm carbos + 1 gm Nitrogen compounds =>
10gm yeast + 97.5gm EtOH + 93.5gm CO2
So 201gm of extract produces 97.5gm of Alc and 93.5gm of CO2 Ignoring a tiny
bit of water used to hydrolyze maltose etc, this means that 191 gm of the
201gm of extract was fermented (95.0% of the lost extract is fermented).
The other 10gm (9 of carbs, 1 of nitrogen cmpds) end up a yeast trub.
4/ 72.9gm/L of extract was fermented (95% of 76.7gm/L) and the remaining
3.8gm/L of extract is used for yeast biomass and consists of 0.38gm of
nitro-stuff and 3.42gm of carbs.
Glucose fermentation releases 0.59kJoule/gm. M&BS states that yeast biomass
carbos (90% of the extract used for biomass) releases about 6kJ/gm.
The fermentation and the more exothermic yeast biomass energy release
(72.9gm/L * 0.59kJ/gm) + (3.42gm/L * 6 kJ/gm) or
5/ 63.5kJ/L is the heat produced with about 2/3rd from fermentation and
1/3rd from yeast biomass carbos!
One small (gram) calorie is 4.184 Joule so this is sufficient heat energy to
raise the fermenter temp by 15C [[63.5kJ/L / 4.184kJ/kcal] if you fermented
in a thermos bottle !!
- -----------
But wait! There's more!
- -----------
I had an offline conversation with the poster and he was using plastic pales
with loosely attached lids. I expect the plastic fermenter yeast were
getting more oxygen - and it doesn't take much to make a difference -
especially if you underpitch like most HBers.
Plastic is a poor thermal conductor, but so is glass. Apparently neither
one is such a good insulator so as to make much difference! (this surprises
me).
Soda glass has bulk thermal conductivity about of 1.35W/m/K while HD
polyethylene is about a third that ~0.4 or 0.5 W/m/K. Many other plastics
are much worse thermal conductors around 0.1 to 0.2 W/m/K. My hunch is
that plastic buckets are a fair bit thinner than the glass but with a
comparable total surface area.
All told the pale is a better insulator but probably only
by a factor around 1.5 or 2 times. The plastic pale
should ferment farther above ambient temps than glass -
but by how much ?
We can ballpark the surface area of a carboy or bucket
at 0.6m^2 or more and the thickness at 5mm or less.
This means it would take at least (1.3*0.6/0.005) or
150 watts to maintain a 1degreeC(K) difference across
the glass surface and at least 50Watts for the plastic
bucket. These are low-ball estimates.
A comparable sized aquarium can be maintained even 10C above ambient using a
25Watt aquarium heater. I've used a ~25W aquarium heater in a 5gal pale to
maintain a ~18C difference (I was culturing lacto's using the pale as a
~100F water bath). So what is wrong ?
Obviously the temperature drop across the pale/carboy
itself is much lower than 1C since the power flux is so
low. Somewhere else in the 'system' the wort is even more
well insulated from the ambient. Poor connection to the
air I think.
If I'm close and a 25W heater can maintain a pale
fermenter 18C above ambient then the thermal
RESISTANCE of wort to environment is 18C/25W or
0.72C/W, but we calculated that the glass is only
about 1C/150W or 0.007C/W or less and the plastic
fermenter is about 0.02C/W or less. Thermal
resistances are additive so these fermenters are a
relatively small part (a few percent) of the thermal
resistance of wort to the ambient environment.
The takeaway is that wort temperatures really should
rise significantly due to heat of fermentation & yeast
growth. The difference in wort temp in glass vs plastic
is pretty small. The temp differences above ambient
should be only a few percent higher in a plastic pale.
A 1/2 inch coating of styrofoam would be necessary
to double the wort to ambient temp difference and this
would provide abt 35 times the insulation as a plastic pale ! You could
ferment in thin copper and you still wouldn't drop the temperature much.
I think I'll perform an experiment or three and verify
and quantify the results. Should be fun.
-Steve
------------------------------
Date: Sat, 15 Nov 2003 16:54:23 +1030
From: "Greg 'groggy' Lehey" <grog at lemis.com>
Subject: Non-digest version?
I've just subscribed to this digest, and I'm very impressed by the
professional standard of most postings. It's a thing I'd like to read
more often... only: I hate digests! It's a real pain to get a thread
intermingled with other topics, and it makes it very difficult to
follow the discussion. This is the only list I know which is
available in digest-only form; couldn't people have a choice of digest
or individual messages, like with other lists?
Before you say "talk to the list administrator", the reason why I'm
sending this to the entire list is because I suspect that there are
plenty of other people out there who'd also prefer individual
messages.
Greg
- --
Finger grog at lemis.com for PGP public key.
See complete headers for address and phone numbers.
------------------------------
Date: Sat, 15 Nov 2003 18:00:59 +1030
From: "Greg 'groggy' Lehey" <grog at lemis.com>
Subject: Re: Refractometer specific gravity conversion
On Thu, 13 Nov 2003 06:17:03 -0600, bcarpenter wrote:
> William Frazier writes:
>
>> Bob Hall has had poor results using a refractometer to determine the
>> specific gravity of wort "So what's the deal? Any tips from
>> refractometer
>> users would be appreciated."
>
> While the subject is on the table, is there such a thing as a quick and
> easy chart to show refractometer readings with a corresponding specific
> gravity number?
>
> All I have been able to locate is (for me) a very complex math formula
> for conversion. I am an artist and gosh darnnit, it's just over me
> head.
Take a look at http://www.lemis.com/grog/brewing/Brix-to-SG.html.
It's based on one of those formulas, and it assumes pure sucrose (cane
sugar) solutions in each case, not maltose or dextrose.
For maltose, the Brix values will be about 2.5% too high. Also, SGs
measure weight, not sugar, so there's no really accurate conversion
for worts.
Greg
- --
Finger grog at lemis.com for PGP public key.
See complete headers for address and phone numbers.
------------------------------
Date: Sat, 15 Nov 2003 11:35:57 -0600
From: Michael Owings <mikey at swampgas.com>
Subject: re: Refractometers
I use one of these routinely, and have had greate results. Like Jeff
Renner, however, I used to have issues caused by evaporation when I
tried to use the refractometer during the boil.
Cooling the sample fixes the problem (I use a method similar to
Jeffs). It's really a great way to monitor the gravity of the wort
during the boil and only takes a few seconds or so to get a reading.
Lewis Bonham's published equations work well for determining gravity
during fermentation, however I have found that using my instrument the
readings tend to be low by 2-4 SG points (about .5-1P) as checked
against a narrow-scale hydrometer. Typically, I split the difference
and add a fudge factor of around 3 SG points when interpreting the
results. This fudge factor may vary with the instrument used and/or
brewery, so YMMV.
Promash has a calculator built in which works quite well for
determining gravity during fermentation using a refractometer. I also
have a program I wrote a while back (before this feature was built
into PM) that calculates the same thing. If there's any interest, I
can post it on my website. I use the "truncated" version of the
equations published on the HBD a while back, but the results are
pretty close to the promash calculator.
Hope that helps -- m
====
Teleoperate a roving mobile robot from the web:
http://www.swampgas.com/robotics/rover.html
------------------------------
Date: Sat, 15 Nov 2003 15:17:05 -0500
From: Mike Ward <mikey at aei.ca>
Subject: slightly OT- sparkling wine
Sorry for the OT post. My usual sources of info are dry on this one.
Alongside my three beers taps, I have separately carbonated 20 litres
of dry white wine in attempt to provide sparkling wine on tap for SWMBO.
To get a champagne-type level of carbonation, 30 psi keg pressure seems
to be required. So far so good. When dispensing at this pressure through
a typical tower style tap, obviously I just get a gusher of foam which
eventually settles into a glass of now flat wine. I have tried putting
up to 15 feet of restrictor tubing (all refrigerated) in attempt to drop
the dynamic pressure at the tap to a level that won't gush. No joy.
I spoke with a gentleman in the keg business (kegman) who advises that
kegging wine cannot be done, and went on to say that I was poisoning
myself with lead being leached out of the tap................
Any ideas how to avoid the gushers?
TIA
Mike
Fellow MontreAler to Alex and John
------------------------------
Date: Sat, 15 Nov 2003 13:58:06 -0700
From: Bob Devine <bob.devine at worldnet.att.net>
Subject: link of the week - Nov 15, 2003
Let's say you like beer and have access to an expensive
photomicrographic system. What would you do? ;-)
http://micro.magnet.fsu.edu/beershots/beerphotos.html
http://micro.magnet.fsu.edu/beershots/index.html
If you don't think beer pictures are enough, here are more:
http://micro.magnet.fsu.edu/cocktails/
Bob Devine
------------------------------
Date: Sat, 15 Nov 2003 13:23:01 -0800
From: Don Van Valkenburg <brewing at earthlink.net>
Subject: RE: origin of Hops
This is an excerpt from an article I wrote for Brewing Techniques in 1995:
"The hop, or Humulus lupulus (lupulus: a little wolf, alluding to the
tenacity with which it clings to any support), is native to three major
continents: Europe, Asia, and North America. Hops are classified in the
plant family of Cannabaceae, which includes the genera Cannabis and
Humulus . The genus Humulus includes two major species: Humulus lupulus
and Humulus japonicus (an annual Japanese hop that produces few resin
glands and is of no value to brewers)."
The complete article is at:
http://calferm.org/edu/hops/Pedigree.htm
Don Van Valkenburg
------------------------------
Date: Sun, 16 Nov 2003 07:37:17 -0500
From: "Jim Yeagley" <jyeag at core.com>
Subject: RE: bottle washer
Using an old dishwasher is a great idea, but be sure to disassemble
everything leading to the pump and thoroughly clean/sanitize. Seems there's
a screen down in the bottom that protects the pump from chewing on various
foodstuffs. If your washer is as old as the one I tried using, there's
probably a good collection of nasties just waiting to spoil a good batch of
homebrew. I ran hot water into it, mixed in an abundant amount of
sanitizer, ran the heater to dry the bottles, and the nasties still won out.
Might even be worth replacing the pump and hoses for good measure?
Jim Yeagley
------------------------------
Date: Sun, 16 Nov 2003 13:06:03 -0500
From: "Dave Burley" <Dave_Burley at charter.net>
Subject: cloudy beer with Wyeast 1028
Brewsters:
Tim writes that his first in a series of house reds was cloudy and the
following batches reusing the same yeast recycled were clear. He remembers a
similar past problem and he wonders if it was a yeast problem.
Assuming that there is not a brewing problem, then the possibility exists of
unflocculated yeast which could cause cloudiness which didn't appear in later
brews when Tim collected the flocculated yeasts for his next brews. He
effectively selected out the non-flocculating strain.
A gelatin treatment on a sample of the first batch will perhaps show if the
problem is unflocculated yeast ( clears with gelatin) or a starch problem (
black with iodine treatment).
London breweries ( from which Wyeast 1028 is derived) in the good old, bad old
days commonly used a blend of sometimes 4 ( or more) types of highly
flocculant yeasts for flavor and non-flocculating yeasts ( so fermentation
stays active and all yeast stirred up) to finish off the fermenation quickly.
The non-flocculating yeast would, of course, explain the cloudiness as it
would not fall out of the beer quickly.
If this is the case, try chilling the beer or adding gelatin or other fining
agent ( perhaps Isinglass from Sturgeon swim bladders to be traditional) to
clarify it.
If you want to preserve something like the original mixture then start with a
fresh sample of 1028, skim the fermentation shortly after the rocky head
develops to remove preciptiated protein, hops and such detritius and then a
day or so later skim and preserve this skimming to start a new brew as they
did in the olden times.
Keep on Brewin'
Dave Burley
------------------------------
Date: Sun, 16 Nov 2003 13:51:00 -0500
From: Darrell.Leavitt at esc.edu
Subject: brewing habits
...brewing a batch of "Chocolate Saison" today (a porter grain bill with a
Saison yeast [4th use...]) and I got to thinking that we need to break
free of our brewing habits. That is, while some things seem to work for
us, we should not be comfortable in the belief that they should be applied
across the board, as it will, with every batch. We need an inner brewing
revolution of sorts ,...a re-evaluation of techniques that allows each brew
to be genuinely new. In other words, if we come to the new brew session
... with old brew habits..., then we have neither broken free of
habit.,...nor brewed a unique or new beer.
Here is an example,...to bring it down a bit: Irish Moss: is there really
any reason to add it (last 15 min) to a porter, or a stout? This is a
habit,
a brewing habit, that ..., while not making me a bad guy, or a bad brewer,
may not be needed for this style. Anyone have any ideas as to why one
should use Irish Moss in a porter. or a stout?
Other brewing habits ....perhaps on the surface, equally innocuous,...
should be discusssed here...at least among those who are serious about the
hobby in particular ,...and their own habits in general.
..Darrell
------------------------------
Date: Sun, 16 Nov 2003 18:37:33 -0600
From: "Jeremy Lenzendorf" <jlenzendorf at progeng.com>
Subject: Corny keg cleaning
Hello all,
I have been given two given two Pepsi ball lock Corny kegs. The only
problem is they have chlorine and/or calcium residue in them (they were
used in a farm milkhouse). What can I use to safely clean them so they
are beer-worthy?
TIA,
Jeremy Lenzendorf
West Bend, WI
------------------------------
End of HOMEBREW Digest #4402, 11/17/03
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