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HOMEBREW Digest #4766
HOMEBREW Digest #4766 Wed 27 April 2005
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
Digest Janitor: pbabcock at hbd.org
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Contents:
link of the week - UK pubs (Bob Devine)
Whirlpooling ("A.J deLange")
RE: Pellets, Flowers & Kettle drains ("Brian Lundeen")
Motorizing a Philmill ("Dan Listermann")
re: Fermentation, Esters, Fusels 1 of 2 ("-S")
re: Fermentation, Esters, Fusels 2 of 2 ("Steve Alexander")
Irish Moss ("Wayne Love")
re: Kvass and Quick Drinks (Rama Roberts)
what's a RIMs worth? ("steve lane")
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Date: Mon, 25 Apr 2005 22:12:11 -0600
From: Bob Devine <bob.devine at worldnet.att.net>
Subject: link of the week - UK pubs
Hmm, my postings are not exactly weekly.
I'm still trying to catch up with other things...
This week, here is the best listing of UK pubs
that I've seen. So while not really homebrewing,
it should be useful for anyone traveling.
http://www.beerintheevening.com/
Bob Devine
------------------------------
Date: Tue, 26 Apr 2005 13:22:14 +0100
From: "A.J deLange" <ajdel at cox.net>
Subject: Whirlpooling
Friction between the wort and the sides and bottom of the whirlpool
cause rapid deceleration of the liquid at these surfaces which results
in an inward current at the bottom, an upward current at the center and
an outward one at the surface. Kunze has a fairly good explanation
starting at page 293 (International Edition).
A.J.
------------------------------
Date: Tue, 26 Apr 2005 08:23:02 -0500
From: "Brian Lundeen" <BLundeen at rrc.mb.ca>
Subject: RE: Pellets, Flowers & Kettle drains
> Date: Mon, 25 Apr 2005 11:28:19 -0700
> From: "Michel J. Brown" <zymurgyst at comcast.net>
> Subject: re: Pellets, Flowers & Kettle drains
>
> Mike Maag says:
> >I have found, what you need to do is let the wort sit (or set) for
> >about 1 hour after chilling, >before you start to drain the kettle.
> >Whirlpool, cover, and let the wort sit for at least 1 hour..
>
> This sounds a little hazardous to me, from personal
> experience. I can see letting the settlement occur for 15-30
> minutes, but a full hour? I dunno about that, Mike, I used
> to have problems in that area until I started chilling
> immediately after the boil. Then everything went as smooth as silk!
Good advice, except that Mike said let it sit an hour AFTER chilling.
Obviously this is for people with immersion chillers.
>
> Well, fwiw, IM is only useful in very light colored worts in
> the first place, and that usually and customarily won't have
> a whole lot of hops.
> Unless you're trying to make an IPA that is.
>
Or a Pilsner. Or a CAP or Classic Canadian Cream Ale (neener, neener,
Jeff). Or a Tripel or Belgian Strong Golden. Or even a Koelsch. If you
are using exclusively low alpha hops, even moderately bittered beers can
have a lot of hop mass.
I would also like to hear your explanation of why IM is only useful in
light colored worts. Are you saying it doesn't contribute to the clarity
of darker worts, or just that you feel it is a waste because you can't
see through it very well anyway? If the latter, I will say that I notice
the dulling effect of a haze even in a very dark beer. Doesn't change my
enjoyment of it, but it does take the shine off of it. Umm, so to speak.
Cheers
Brian, in Winnipeg
------------------------------
Date: Tue, 26 Apr 2005 09:27:30 -0400
From: "Dan Listermann" <dan at listermann.com>
Subject: Motorizing a Philmill
<I recently bought a PhilMill 1 and recall a page of instructions that
included the warning about *motorizing* because of the risk of
damaging the roller and/or plate with rocks or bits of metal that are
sometimes found in grain.>
This is there not as a warning against motorize the Philmill, but as a
blanket statement about what can happen to any mill. Actually I am having a
hard time remembering any customer complaint about this since we went to the
coarse knurling and hardened roller and plate ( many years ago) so it might
not need to be in the instructions anymore.
<It does recommend using a *drill* (rather than a belt driven or direct
drive mounted motor) and holding it in your left hand so that if an
obstruction is encountered the drill will rotate out of your hand and
stop rather than rotating into your hand and possible injuring your
wrist.>
This is not to be misconstrued as recommending against belt driven or direct
drive motorizations, they are fine. It is a recommendation as to the
easiest way to motorize a Philmill. A lot of people have half inch corded
electric drills.
Dan Listermann
------------------------------
Date: Wed, 27 Apr 2005 05:31:25 -0400
From: "-S" <-s at adelphia.net>
Subject: re: Fermentation, Esters, Fusels 1 of 2
Matt B asks.
> I wish someone or some book had told my these things
> (and not filled my head with other things) when I
> started brewing.
Sorry, but many HB books are filled with half-truths and
approximations/simplifications to the truth. Some are momilies as we call
them on HBD. Many are short-cut simplified explanations of what is
happening. Also there are a lot of unknowns in brewing research.
>1. When you pitch the yeast, each cell has a "lag
>time" while it reaches some rough equilibrium with its
>new surroundings, and then it begins fermentation.
Not exactly. There is a lag period after pitching *dormant* yeast (dried
yeast, or from a yeast cake for example) when there is no *growth*. There
absolutely is fermentation during this period. Immediately after pitching
dormant yeast, triggered by oxygen, begin fermenting their internal
carbohydrate stores and building proteins and lipids for later growth.
Among these proteins are cell membrane proteins to permit facilitated
diffusion of glucose (later maltose) through the membrane and into the cell.
The majority of what HBers call the "lag period" has to do with the fact
that wort won't begin to bubble CO2 until the wort reaches saturation. In a
20L/5.3gal batch this means the yeast produce about 20L of dissolved STP CO2
(CO2 at STP is 44grams per 22.4L) before the bubbler starts bubbling. So
roughly 40 grams of CO2 are produced by fermenting 80gm of sugars and only
then does the fermentation lock start bubbling. 20L of 12P wort typically
has about 1.6kg of fermentable sugar, so yeast must ferment about 5% of the
total fermentables before the bubbler starts up ! No wonder there is a
several hour delay.
>2. The rate of this fermentation is determined by
>yeast energy needs, so it only occurs at a reasonable
>rate when a cell is actively reproducing.
Yes. Yeast use some sugar carbon for cell formation (primarily mannose cell
wall I think), and use some energy for metabolic maintenance. Very late in
the fermentation, yeast convert some fermentables to storage carbohydrates.
Aside from that, fermented sugars energy is used for growth.
>3. Hence, in a decent fermentation the total yeast
>growth is proportional to the amount of sugars
>consumed (i.e. a specific amount of yeast growth is
>required for a given beer). I think Steve agrees with
>this.
Right. The biggest deviation from the "proportional" rule is that all yeast
use some background level of energy for maintenance, not growth. If you
pitch really big, you'll have higher maintenance energy costs, and less new
growth per unit of fermentation, but I think we are talking 10% type
differences at most.
>4. This required amount of total yeast growth can only
>occur if there are sufficient nutrients (FAN, amino
>acids, minerals). If a nutrient runs out before the
>sugars do, fermentation will "stick." [...]
Right. Many complications here but I can't disagree with this outline.
Yeast in "normal" brewery conditions finish the ferment up against both
sterol/UFA (oxygen-lipid) limitation and also amino acid limitations.
Metal ion co-factors are low in finished beer. There are several dozen
other nutrients that are all over the map in finishing concentration and
also yeast requirement.
>5. Since we require a given amount of growth, choosing
>the pitching rate is the same thing as choosing how
>many generations of yeast will have to be produced.
>(!)
Yes ! That's a good way to state the problem. We could add a single yeast
cell or pitch an entire yeast cake and he difference is primarily the number
of generations of growth to ferment all fermentables. The other oddity is
that oxygen is only available for the first few hours even if we only pitch
one cell, and yeast have limited O2 storage capacity for sterols and UFAs.
So the *total* amount of O2 uptake is related to the amount of yeast pitched
(to a limit) and this in turn determines the total sterol/UFA in the
fermenter which impacts the ester & fusel levels.
>6. To keep reproducing for a given number of
>generations, the initial yeast cells must store up
>enough cell-wall material (sterols). Oxygen is
>required to make this material. It cannot be made
>once fermentation activity is significant, because the
>oxygen is quickly scrubbed out of the wort by the CO2
>bubbles. (I am ignoring trub and late oxygen
>additions.) Hence, the fermentation go to completion
>only if the average cell of pitching yeast gets enough
>oxygen to make and store enough sterols to reproduce
>for the required number of generations.
Right concept, but the fate of the O2 isn't quite right. The O2 is gone
before CO2 scrubbing is significant. The anti-oxidant chemicals in wort
(primarily phenolic compounds) will remove saturation levels of O2 in a
matter of hours. The consumed O2 is used to make bother sterols and
unsaturated fatty acids (UFAs). Both lipids have critical roles in cell
membrane properties.- such as selective permeability and cool temperature
pliability.
>7. Some or maybe even all of this oxygen can be
>provided in a yeast starter. Hence, for those of us
>without oxygen tanks, etc, making a well-aerated yeast
>starter can really help.
Right - this is the Bass process where carefully oxygenated yeast slurries
are pitched into unaerated wort for successful fermentation. Never forget
that different yeast have very different efficiencies at converting O2 to
sterol+UFA. Some ale yeasts require 'dropping' O2 additions for example.
So beer yeast might typically create enough of these lipids to share with 10
or so descendents, but also the amount which descendents need to survive is
dependent on things like the gravity/osmotic pressure of the wort/beer.
(more)
------------------------------
Date: Wed, 27 Apr 2005 05:35:32 -0400
From: "Steve Alexander" <steve-alexander at adelphia.net>
Subject: re: Fermentation, Esters, Fusels 2 of 2
(continued)
>8. For a given temperature and yeast strain, there is
>basically a set amount of fusel, ester, and diacetyl
>production that will occur during a full, strong
>fermentation. Pitching rate, aeration level, etc,
>don't matter much as long as the fermentation is
>strong to completion. If the fermentation "sticks"
>(i.e. something else runs out before the sugar does)
>then additional fusels and esters may be produced, and
>the yeast will not be healthy enough to reduce the
>diacetyl.
The "mix" of esters is dependent on yeast choice(genetics) and the quantity
is highly dependent on temperature probably due to enzyme reaction rates.
Fusels, an ester precursor but usually not a gating factor for esters, are
significantly impacted by amino acid levels (high or low) and so then even a
little difference in growth quantity due to pitching level and adjunct amino
properties can make some modest difference. One major culprit in both
ester & fusels has to do with the wrong bits(keto acids and fusels) leaking
through shoddy cell membranes to places they don't belong. Here the
statement is clear cut - lower temps, better sterol+UFA levels in yeast, and
lower osmotic stress lead to lower final fusel and ester levels. Fusels
are produced early and again mid-to-late due to amino abundance early and
later amino deficit. Esters are produced primarily mid-late when the fatty
acid synthesis mechanisms are shutting off and esterification enzymes
contact the fusels leaking about. Given good quality wort and a "normal"
pitching level the major factors in fusels&esters are temp and aeration (to
produce UFA and sterols) and these two can't be dismissed.
Where I may have led you astray is in saying that oxygen can have anomalous
impact on fusel & ester levels. See this note and addenda by the long lost
Andy "Wolgemuth" Walsh,
http://brewery.org/brewery/library/EstFormAW0696.html It's now quite clear
that the dual enzyme catalyzed esterification of fusels via acylCoA groups
is the primary mechanism of ester formation, but there may easily be other
factors, such as wort lipid levels and oxygen which throw a money-wrench in
the enzyme expression or activity and bollox up the ester formation. The
mechanism seems correct, but some brewing conditions have an unexpected
impact.
I didn't previously post on VDKs. The VDKs, diacetyl(aka 2,3-butanedione)
and also 2,3-pentanedione are an indirect result of the amino acid
metabolism. When yeast have low amino levels in wort they synthesize the
several which they can. There is a clear path from pyruvate thru
alpha-acetolactate ... to valine synthesis. The alpha-acetolactate
intermediate is also decarboxylated to form diacetyl. There are parallel
steps from threonine to ... isoleucine, with intermediates hijacked to form
2,3-pentanedione(a VDK) by decarboxylation. These VDKs are formed early to
mid-fermentation since the amino acids in question are taken up early. The
intermediates (alpha-acetolactate) leak into the extracellular wort at high
rates and are externally decarboxylated. The VDKs are reduced to less
flavorful acetoin (and 2,3,pentanediol) late in fermentation as part of the
"reduce the environment for redox balance" campaign of yeast.
Anyway, the focus is properly on amino acid metabolism. Either amino excess
or deficit create keto-acid pools. Leaky keto pools have several fates; they
are decarboxylated to aldehydes, then reduced to fusels, the fusels in turn
are enzymatically catalyzed to esters. Minor amounts amino acid synthesis
process keto-acids to alpha-acetohydroxy acids and these are decarboxylated
to VDKs. The main "pipeline" pathway from glucose to pyruvate to
acetaldehyde to ethanol insures that high levels of pyruvate (a sort of
trivial keto-acid) are available as a precursor to diacetyl production as a
byproduct of valine synthesis. All of these can be modulated by amino
acid concentrations [for example several experiments involved adding amino
acids late and significantly reducing fusels , but also probably harming
beer flavor].
>Maybe I was out of the loop, but the vast majority of
>this was completely lost on me as a beginner, even
>after reading the popular books. This may be because
>these statements are not true. One innaccuracy may be
>if "second generation" cells also have access to
>oxygen, but it doesn't change much. I'd appreciate
>any comments on whether this picture is the truth, and
>where it may be glaringly not the whole truth.
You're certainly getting a more complete picture and are thinking along the
right track Matt, but that picture is necessarily a more complex and
confusing one. Too deep for amateur books. If you'd like to verify and
deepen your understanding of what yeast are up to in your fermenter I'd
suggest you look into some of the professional books. Boulton&Quain,
"Brewing Yeast & Fermentation", Blackwell Science, 2001 covers this entire
topic and is quite readable. Very good book IMO. "Malting & Brewing
Science" vol 2, covers much of the same material circa 1981. Despite the
age M&BS was so carefully written that it's hard to find any errors, merely
limitations. The authors knew both what they knew and what they did not
know and distinguished the two carefully.
.If you can find a good brewing journal or even some of the microbiology
journals in a university library you're far ahead of the game. Rose's "The
Yeasts" is dated but worthwhile. Gerald Reed and ??? Nagasawith ???
published a nice book called "Yeasts" in the 1980s. Some of the more
general biology/metabolism books cover a lot of the basic material and give
a much more general overview. I like "Microbiology of Microorganisms" by
Brock (about 10 different editions, some with co-authors, often available
for a few $$ at half-price books) - very readable for an outsider like me
(physics). "Biochemistry" by Mathews&VanHolde is aimed at med students
studying human metabolism, but it's so d*mned good I highly recommend it for
this sort of general biochem/metabolism topic. Stryker, "Biochemistry" and
Lehninger "Priniples of Biochemistry" are the classics, but I prefer
Mathews&VanHolde.
-Steve Alexander
------------------------------
Date: Wed, 27 Apr 2005 09:28:32 -0300
From: "Wayne Love" <wlove at claired.com>
Subject: Irish Moss
Michel Brown posted "...... fwiw, IM is only useful in very light colored
worts in the first place, and that usually and customarily won't have a
whole lot of hops. Unless you're trying to make an IPA that is."
That's the first time I heard that IM is only useful for light coloured
beers. Is this every bodies experience or one of the areas where opinions
vary. What is the reason IM doesn't work with darker worts? And what impact
does higher levels of hopping have on how IM performs?
Wayne Love
Rothesay, NB
Canada
"Your liver is an evil organ and must be punished"
------------------------------
Date: Wed, 27 Apr 2005 13:44:20 -0700 (PDT)
From: Rama Roberts <rama at sun.com>
Subject: re: Kvass and Quick Drinks
> From: Alexandre Enkerli <aenkerli at indiana.edu>
> Subject: Kvass and Quick Drinks
>
> Been thinking about this while reading Mosher's /Radical Brewing/.
> Can't brew right now (living on a dry campus) but will soon be back to
> brew-friendly Montreal.
> Have people experimented with kvass and other quickly fermented drinks?
> One advantage I see is that one could experiment with all sorts of
> flavourings (herbs, spices, fruits...) and then transfer some of those
> experiments to beer. It sounds like kvass itself was often flavoured
> with peppermint. Also, it seems to have some of sourness/tartness which
> could in fact make it quite refreshing...
I've sort of tried this with a Berliner Weisse, and won't try it again
even though it was quick and easy. My experiment was an extract based,
lactic acid spiked brew. (Extract because Ray Daniels in Designing Great
Beers suggested wheat extracts won as many competitions as all-grain
brews. Lactic acid because it was easy to adjust sourness- no surprises
due to a lacto bug puttering out or going overboard.)
After years of all grain brews, it was refreshingly easy to whip out an
extract based beer. I don't recall even needing to secondary it- so it was
bottled quickly.
Thing is, the beer lacked depth. It tasted exactly like what it was- a
simple sour wheat beer. I walked away from that experiment with the
conclusion that simply spiking a beer isn't going to add significant
character to an otherwise "blah" beer. YMMV.
Next time I feel the need to whip out an uber-fast brew, I *might*
consider doing a partial mash with some home roasted grains.... or just
buy commercial beer until I have enough time to do an all grain batch.
- --rama
------------------------------
Date: Wed, 27 Apr 2005 16:24:37 -0500
From: "steve lane" <tbirdusa at hotmail.com>
Subject: what's a RIMs worth?
I've been down with a bad back for going on three years and have just lost
interest in brewing. Like most things I do.... I went full into brewing and
put together a rather nice RIMs that will be going up for sale. It is
typical 2 tier, half barrel converted kegs system. PID with thermocoupler
and element in the HLT and a ramp capable PID on the RIMs chamber. Two
burners, one on the boiler and one on the HLT to get it up to temp.
Chillzilla counterflow chiller with false bottom in the MT and 1/2" welded
coupling throughout the various vessels.
The system is in KC, MO.
What is a fair asking price for this setup? I've got around $1400.00 in it
with out any labor....which was alot!
------------------------------
End of HOMEBREW Digest #4766, 04/27/05
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