hist-brewing: multiple rackings

Paddock Wood Brewing Supplies orders at paddockwood.com
Tue Nov 27 16:55:40 PST 2001


LURK MODE OFF

Jim Booth writes:
"There is some concern about thick layers of yeast laying for long periods
of time as occurs in the aging of wine, as for periods of years.
Autolysis is rarely a problem with beer aging as it is months not years."

While autolysis is not the bogeyman that many think it is, there are
definite off flavours to be picked up from the trub through extended
contact. Even if that contact is months instead of years.  The issue really
is: "Will extended contact with trub affect the flavour of the beer?" The
answer isn't clear, even from the 'gurus' on the HBD.  In a nutshell: trub
contains fatty acids - lipids, which are beneficial to yeast growth, and
also provide nucleation points for CO2, thereby encouraging a healthier
fermentation and clearer break. BUT, trub, specifically the lipids, also
cause instability. They enable auto oxidation, which can lead to buttery or
stale metallic flavours.

But getting back to repeated rackings and staling: what about the oxygen
from repeated racking? Jim writes "The more racking you do the more
contamination you add to the process, and the more oxygen.  Both are bad
when beer is aging."

Absolutely. Jim's suggested practice of bottling from the primary for ales,
and from the secondary for lagers to avoid oxidation is excellent, and one I
do as well, but I have also used tertiaries when I am trying for a stable
long term brew. If I am using the single stage method, I try to ensure that
the wort is off the trub within 10 days of fermentation completing (about 2
weeks from pitching for most ales, and 2-3 weeks for lagers).

If brewers are accomplished, then multiple rackings can be done with little
risk, especially if they have the ability to CO2 purge the containers.  But
many brewers do not have the ability or do not wish to, it's not in period.
At our brewshop we strongly recommend the single stage method for most
brewers because the advantages of 2 or 3 stage brews are not usually
compensated by the benefits.  Better to have a slightly larger layer of
sediment in the bottle or keg than have stale contaminated beer.

The best thing you can do for the stability of your beer is avoid oxygen
contact unless you need to aerate the cooled wort.  A very well known author
and award winning homebrewer pushes his beer from the kettle through a
closed system into small purged Cornelius kegs immersed in flowing ice
water. His beer is not exposed to oxygen at any point. He doesn't need to
aerate the cooled wort because he pitches the a sufficient population of
active viable yeast grown separately in aerated wort, more than most of us
would be able to practically. Yeast needs oxygen for growth, not
fermentation. (nitpickers retire to the HBD for biochem geek wars- for
practical purposes, yeast do not need oxygen for fermentation),

So racking can lead to oxidation and trub can lead to oxidation. What's a
brewer to do? Moderation and practicality in either approach is the key. The
general consensus on HBD and elsewhere, as much as there can be a consensus
in homebrew circles, is a small amount of trub will help a vigorous and
healthy ferment, but extended contact may produce faster staling and
unstable beers. In practice that means as clear wort as possible into the
kettle, and chilling in the kettle or cooling tank to prevent excess trub in
the primary fermentor.  If you use a counterflow chiller or simply let the
wort cool in the primary so that all the break is in the primary, you may
wish to rack after 2 days to prevent excess contact with the trub. Or be
sure to get your beer off the trub in a timely manner.  I just use the 10
day guideline.

Jim writes: "Think about it.....how could the process of racking or stirring
the beer
contribute to settling out."

Ah! I'm thinking about it, and this is an easy one! And I'm on far firmer
ground than with my shaky understanding of the biochem above.  Winemakers
are very familiar with 'degassing' the wine by stirring. Since beer is
fizzy, it often isn't a concern unless it is going to be filtered, but stirr
ing or racking accomplishes two goals in one simple motion. It helps knock
dissolved CO2 out of solution which can inhibit fermentation and also
inhibit yeast settling, and rouses the yeast back into suspension. Both will
contribute to a healthier and more complete ferment, which in turn
contributes to a faster clearer flocculation and settling. Done carefully
there is little risk of oxidation.

For more geeky explanations and research than mine check out:

http://www.bodensatz.com/homebrew/columns/jirvine/trub.html for trub and
flavour stuff

AND

http://www.nysaes.cornell.edu/fst/faculty/siebert/abstracts/abs029.html for
an abstract on trub, dissolved CO2 and fermentation.

A quick search through the Homebrew Digest archives (www.hbd.org) for lipids
and trub will also yield all kinds of holy war results...

For a more immediate data point: I recklessly let a potentially wonderful
Czech Pils sit in the primary on the trub at about 0 C after fermentation
for about 5 months. Result? Oxidized stale beer. Not undrinkable, but
definite metallic and buttery flavours. What a shame. Had I bothered to rack
it even once, the minimal oxygen contact would have done far less damage
than the extended trub contact. The beer scientists inform me that the
process was significantly slowed by the cold temperature, but not prevented.

Historical brews? I'm sure that someone here can correct me if I'm mistaken,
but all my reading indicates that the cask examples were for the most part
either consumed fairly quickly (tapped within a month of kegging and
consumed within 2-5 days of tapping) while fresh and therefore stability and
oxidation were inconsequential, or for the British ones anyway, were stale,
papery, sherry like horse sweaty saddle leather lactobacillus infected nasty
things, blended with fresh beer to be palatable. Having brewed a few
lactobacillus beers myself, I can attest that the taste is not entirely
unpleasant in historical porters, or sweeter brews. Old beer was stale.
Period (pun intended). And often infected. Modern chemical spectrography has
shown that the high hop concentrations in aged brews such as IPA masks the
staling compounds but does not inhibit their formation. The stronger
alcoholic brews also withstood long term aging better, but were oxidized,
and modern oxidative styles still retain the sherry like oxidized notes of
their predecessors.  The German lagers fared better, there were no spoiling
organisms in the ice caves, and the cold slowed down the staling process.

On a more practical note: if you wish to clear your beer of yeast, isinglass
is unsurpassed, but it must be properly prepared. I learned my lesson from
Roxy Hastings, an excellent Canadian brewer. Although I typically use the
single stage method, I followed her fining and 3 stage racking advice and
had a 1.060 beer crystal clear in 6 days from pitching (I pitched a WHACK of
yeast- fermentation was 3 days, clearing was 3 days). I was so impressed by
the results from following her advice I posted them on my shop's website
(commercial warning: While I am completely sincere, I AM as affiliated as
all get out, my opinion is biased and I have a vested interest in convincing
you to use the type of collagen finings I sell, but of course you can get
isinglass anywhere, but it is best if it is fresh-refrigerated- if it is in
liquid form)

www.paddockwood.com/catalog_chemicals.html#KEGGING

If you wish to avoid finings, once fermentation has ceased, crash cool the
beer as quickly as possible to about freezing 0 C. Stick it outside if you
must. The rapid cooling will help the yeast to settle. I don't know WHY it
works yet...

RESUMING LURK MODE

cheers,

Stephen Ross -- "Vitae sine cerevisiis sugant."

Paddock Wood Brewing Supplies, Saskatoon, SK, Canada
orders at paddockwood.com  www.paddockwood.com





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