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HOMEBREW Digest #5056
HOMEBREW Digest #5056 Tue 12 September 2006
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
Digest Janitor: pbabcock at hbd.org
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Contents:
Re: Vienna Standard (Eloise & Stuart Grant)
Re: Hop Plants too Old? ("Greg 'groggy' Lehey")
GABF + hikes ("Bob Devine")
Re: yeast settling and crash cooling ("steve.alexander")
Mead for dummies? ("drscholtz")
GABF and hikes near Denver ("Mike Racette")
Re: yeast settling and crash cooling (Matt)
Beer Color 1 ("A. J. deLange")
Beer Color 2 ("A. J. deLange")
Beer Color 3 ("A. J. deLange")
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Date: Tue, 12 Sep 2006 13:47:12 +1000
From: Eloise & Stuart Grant <grant1 at curl.aunz.net>
Subject: Re: Vienna Standard
Pete Limosani wrote:
>Which Vienna/Marzen/Octoberfest should I hold up as my gold standard if I
>want to win in this category?
>
>Is it likely that the Paulaner's that I bought would have tasted better
>when it went into the bottle than when it came out? Like
>green-bottle-Pilsner-Urquell does when distributors and retailers don't
>handle it properly? Or is Paulaner's just a bad choice for this style?
>
>Your thoughts are much appreciated.
I think I remember Michael Jackson stating that Oktoberfestbiers from
the more popular German breweries (HB, Paulaner, Hacker-Pschorr?,
etc) have diminished in the last 5-10 years. Your experience with
Paulaner's O'fest - which mirrors mine - seems to anecdotally support this.
I think MJ recommends some US-made O'fests as the closest to
traditional quality. He mentions Gordon Biersch Maerzen and Penn
Oktoberfest - no idea if either of those breweries are still around.
No chance of getting them here in Australia even if they were...
Cheers
Stuart,
Launceston, Tasmania, Australia.
------------------------------
Date: Tue, 12 Sep 2006 13:41:21 +0930
From: "Greg 'groggy' Lehey" <grog at lemis.com>
Subject: Re: Hop Plants too Old?
On Monday, 11 September 2006 at 12:09:25 +0200, Thomas Rohner wrote:
> Hi Dave
>
> when i remember correctly, the hop grower told me he changes the plants
> every 10-15 years or so. The harvest reaches maximum in about 3 years and
> then starts to decrease slowly, depending on your pruning the roots. I think
> they would last much longer, but then the pro's choose new varieties that
> are more resistent and or yield more alpha's or are superior in another way
> compared to their ancestors.
Would this be in Tettnang?
> (Pruning the roots is very important)
Do you have details of how to prune them?
Greg
- --
Finger grog at lemis.com for PGP public key.
See complete headers for address and phone numbers.
------------------------------
Date: Mon, 11 Sep 2006 21:54:43 -0700
From: "Bob Devine" <devinebob at gmail.com>
Subject: GABF + hikes
"JONES,AARON K" <kjones1 at ufl.edu> asks:
> On a related note, the fiancee and I are looking to do some hiking
> on that Sunday. We were thinking about heading over to Rocky
> Mountain National Park.
Ahhh youth. Drink all day and then go hiking!
A word of warning, going from sea level (univ of Florida)
to a strenuous hike at Estes Park (2 miles up) will be hard
unless you are in tip-top shape or have acclimitized to the
altitude. Even going from Florida to drink in Denver may
spin your head, not to mention your stomach.
Here's a link for day hikes around Rocky Mtn park
(hint -- bring a camera, binoculars or a spotting 'scope
because the big animals might be viewable in late September)
http://www.trails.com/activity.asp?area=1202
Otherwise, there are zillions of hikes just west of Denver
(heck, hike Golden to see Coors!) or around Boulder
so you don't have the long drive up mountain roads.
And do believe the weather reports. Snow is possible.
On the other hand, if somebody offers you Rocky Mountain Oysters,
be sure to grab a BIG plate of them... ;-)
Bob "ex-Coloradoan" Devine
------------------------------
Date: Tue, 12 Sep 2006 03:43:08 -0400
From: "steve.alexander" <-s at adelphia.net>
Subject: Re: yeast settling and crash cooling
Matt wrote:
> Steve sez: "If your yeast run out of sugars while growth is still
> possible, then they'll typically drop cleanly and fastest at the higher
> temp."
>
> ...and this surprises me.
There are several things to keep in mind.
The process of becoming flocculent involves genetic expressions which
greatly
impacts the cell surface and which is environmentally triggered. The
leading
mechanism(FLO1) yeast cell surface becoming covered in long stringy
lectin-like proteins. Photomicrographs show yeast cells transforming from
cue-balls/lunar-surface to fur-balls. It's quite dramatic.
There are many complexities to the triggers, but under "normal" brewing
conditions growth limitations of several types can trigger the surface
changes
that lead to flocculation. Growing yeast do not flocc; floccing yeast
are not
growing. Once the cell surfaces change they become capable of attaching
to other yeast cells and forming larger aggregates of cells or floccs.
Fermentation produces CO2 that will continue to re-suspend yeast.
Flocced yeast drop faster than single cells. So stopping or finishing the
fermentation is needed to get good clarification.
It's said that dropping yeast or floccs don't follow Stokes law (more outlaw
behavior !), but the discrepancy is wrt the estimated "radius" of a cell
when
it may be attached to protein or phenolic particles. So Stokes law applies,
but not a naive estimate of the cell radius.
===
The ultimate growth limitation is (lack of) sugars, so it shouldn't be
surprising
that fermenting out most of the sugars normally triggers the cell surface
changes and cause flocculation. Also the end of fermentation removes the
CO2 production that drives resuspension. Sugars and particularly maltose
and mannose can induce de-flocculation or prevent flocculation in many
cases.
Cold-shock stops or greatly reduces fermentation, so the CO2 driver stops.
Also the cold stress may trigger cell surface changes too.
> I can believe that inanimate particles will
> drop through beer faster at warm temps than at cold temps, because the
> beer is more viscous at cold temps (and probably for other reasons I
> haven't thought of).
>
The last time I checked physical laws apply equally to animate and inanimate
objects. Even single cells drop, just more slowly. The "trick" is
that the yeast
drop faster won't as readily re-suspend if they are flocculated.
Agitation is necessary for flocculation !! This seems contradictory,
but even
yeast cells have formed sticky lectin-like surfaces they to not
automatically form
clumps of cells unless gently agitated. This is accomplished in commercial
fermenters just by the thermal convections, but in HB fermenters I *suspect*
gently mechanical agitation may help in some cases.
Unstable complexes of proteins and phenolics can form at lower
temps (e.g. chill haze) and these can be filtered out or even sedimented
via lagering if kept at the lower temps. Yeast are not subject to this
effect.
> But if what Steve says is true, it begs the question "what is the point
> of the crash-cooling step that is practiced by virtually all commercial
> ale breweries in the US and Belgium."
Money ! Commercial breweries can probably shave a day off the fermenter
dwell time by crash cooling once there is only one or two SG degrees left.
The fermentation stalls, and the yeast drop well enough. Of course the
chilling
costs something, but they were going to chill the beer later anyway.
My point is that cooling isn't necessary nor is it an improvement if you
wait till the sugars are gone (and that this is some reasonable period
of time).
> I
> understand that bottling filtered and force-carbonated beer is much
> easier if the beer is very cold,
>
Of course the chilled beer & yeast are more stable. Filtration costs are
greatly dependent on the amount of stuff in suspension. But also cold
stabilization before filtering causes those unstable protein+polyphenol haze
particles to become filterable.
> but this does not explain either the
> several day "lagering" period that is generally observed, nor why
> crash-cooling is standard procedure even at breweries that
> bottle-condition.
>
Traditional lagering has the same point as cold filtering, except that
the unstable
complexes can sediment after weeks in the cold. Also to re-ferment or bottle
condition you want to remove the greatest amount of the original yeast
possible
(Kunze) to avoid autolysis flavors.
> I always thought the reason for crash cooling is that it makes the beer
> fall clear faster,
I think "sooner" rather than "faster" is a more correct statement.
Crash cooling
normally starts sooner to shave time off the fermentation cycle, BUT the
rate of
clearing (and there are ways to measure this) will certainly be slower
because of
viscosity. Overall it's a timesaver, but a necessary or even desirable.
> If you pitch the proper amount of a strain like Whitbread, it
> probably doesn't matter. But not every strain flocculates like
> Whitbread, even in a healthy ferment.
Good point - the very flocculent UK ale yeasts seem to have a poor
ability to
accumulate O2 products (sterol & UFAs) so they are poorer at the anaerobic
phase. They reach growth limiting stress conditions earlier and flocculate
earlier.
> I would expect less flocculant strains to drop clear faster if the
> beer is cooled, and that this effect could be significant even in
> a healthy ferment. Is this not so?
>
No - just the opposite. Once fermentation ceases, single cells drop slower
than flocc'ed aggregates of brewing yeast because of their smaller size and
they also drop slower at lower temps due to the increased beer viscosity.
Here http://en.wikipedia.org/wiki/Stokes_law and look at the second eqn
describing the downward velocity Vs. The downward rate is inversely
proportional to the viscosity, and increases as r^2 - the radius squared of
the particle. So smaller (single cell) clumps fall slower, and slower
yet in the
more viscous colder beer.
> To put it in practical terms, suppose I ferment an ale at 68 degrees,
> and the fermentation proceeds with vigor until it suddenly stops at the
> gravity I expect (i.e. the yeast are strong until the sugar runs out).
> However, the yeast is not highly flocculant and there is clearly still
> some in suspension. Will it clear faster if I leave it at 68 degrees
> or if I drop it to 35? Or is it so strain-dependent that the answer is
> meaningless in general?
>
Given the same extent of floculation (that is aggegation) and the same (lack
of) fermentation and therefore CO2, then the warmer fermenter drops clear
of yeast cells sooner due to the viscosity term in Stokes law.
-S
------------------------------
Date: Tue, 12 Sep 2006 07:27:14 -0400
From: "drscholtz" <drscholtz at comcast.net>
Subject: Mead for dummies?
I have been brewing for a couple of years now and I am not a fan of
honey based brews but...
I have been asked by a friend to make a mead or mead like concoction for
a colonial period tavern night at a local historic home. Can anyone out
there
help me out with a no-fail recipe that can be served 6-7 weeks from now?
Thanx, Brendon
------------------------------
Date: Tue, 12 Sep 2006 09:32:56 -0600
From: "Mike Racette" <mike.racette at hydro-gardens.com>
Subject: GABF and hikes near Denver
I probably won't make it to the GABF this year, but as far as hiking I think
RMNP sounds like a good idea this time of year. I would recommend the Wild
Basin area near Allenspark. Always less crowded and lots of nice waterfalls.
Then afterwards, you can have a brew in Lyons at Oskar Blues or in Boulder
at the Mountain Sun.
------------------------------
Date: Tue, 12 Sep 2006 08:48:47 -0700 (PDT)
From: Matt <baumssl27 at yahoo.com>
Subject: Re: yeast settling and crash cooling
Steve makes some interesting points about flocculation. I think the
heart of what he has said is that yeast will flocculate if and only if
they have for some reason finished growing, and that that stuff falls
faster in warm beer than cold (Stokes). Hence the only purpose of
cooling (with respect to flocculation) would be to arrest fermentation
so that flocculation occurs sooner.
This explanation is not consistent with what I have heard from
commercial brewers (which obviously doesn't make it wrong). Recently I
was lucky enough to visit Belgium and ask some questions, and one thing
that surprised me was that even the traditional brewers (De Dolle, St.
Bernardus, etc) crash and lager their beer. When I asked why, their
answers were the same: to get the yeast out. I hear the same
explanation from some American commercial brewers--but as they
generally filter they tend to mention both the yeast AND the haze
aspect.
The contradiction with what Steve has said (or my reading of it,
anyway) is that these brewers seemed to say that *even after
fermentation has stopped*, crash-cooling can cause the yeast to fall
clear sooner. Given Stokes' Law, the only reasonable mechanism for
this would be improved flocculation induced by the cold (which is why
things might be different for inanimate vs. animate objects, by the
way). So I think there are two possibilities:
1. Even after fermentation is over, cold shock can cause yeast to
flocculate more effectively than they already are. It is hard for me
to believe this is not true, at least for some common strains.
or
2. For these brewers, "fermentation has stopped" doesn't necessarily
mean that every last bit of sugar is gone, but rather that they are
okay with the attenuation as is. Thus, as Steve says they are simply
arresting fermentation prematurely, to induce flocculation. For some
of these breweries (the American ones that are going to filter anyway)
this is easy for me to believe. For De Dolle, Kerkom (who allegedly
primary for 3 weeks), St. Bernardus, et al, I am more skeptical.
I don't know where the truth lies. Right now my interest in this is
really driven by the question of "how do I get the yeast to drop clear
as fast as possible, so I can drink my beer before the (probably
thermo-lactic) infection that has been plaguing me ruins it?" And
going forward, there is a much more desirable solution to that problem.
(See my previous question about boiling water).
Matt
------------------------------
Date: Tue, 12 Sep 2006 18:25:54 +0000
From: "A. J. deLange" <delange-aj at zai.com>
Subject: Beer Color 1
Is it time for a review of the subject of beer color? It hasn't been
much discussed in quite a few years. The current excitement stems from
the discovery that perhaps the widely accepted "fact" that beer doesn't
follow Beer's law was promulgated as the result of improper
interpretation of spectrometer readings and might in fact be valid. This
could have implications on the way homebrewers determine beer color
revalidating ideas that were dropped because of the Beer's law thing.
Let's start with what beer color is. Before getting to beer color we
need to know what color is, a little about how we humans perceive it and
how it is measured in the lab. We have three types of color recepters in
our eyes which respond to broad bandwidths of light centered roughly in
the red, green and blue portions of the spectrum. Scientists at the CIE
measured the responses of these sensors to monochromatic light way back
in the 30's and published a set of "color matching functions" which are
the sensitivity of each sensor type to each visible wavelength. These
functions (for the "two degree standard observer") are the basis of
color science today though many advances have been made since then. In
particular we don't often use the R,G and B color matching functions but
rather the X, Y and Z functions which are derived from the R,G and B
functions. Y has physical significance: it is representative of the
perceived brightness of a color. x = X/(X + Y + Z) i.e. X normalized by
the sum and y = Y/(X + Y + Z) convey no information about brightness
and, as Y conveys no information about color all the color information
must be contained in x and y. In color TV transmission Y modulates the
amplitude of the transmitter's carrier and if the signal is received on
a black and white set, a properly toned black and white picture is seen.
x and y modulate the color subcarrier and it is from this signal that
all the color information is derived. The magnitude sqrt(x^2 + y^2)
gives the purity (saturation) of the color and atan(y/x) the value or
hue. I'm simplifying lots here. Non linear transformations, rotations
etc. are done on all three to match the responses of cameras to the
responses of phosphors on TV screens and to cast the coded color into a
space more directly proportional to the human response to color
differeces. Some of these spaces are L*ab (used by color scientists) and
Yuv (used by TV and video systems). In each of these the first letter
contain brigtness information and the second 2 lower case the color
information.
To calculate the color of something, in particular, beer, you put it in
a container, hold it up to the light and measure the amount of light at
each visible wavelength which passes through it. The color you see
depends on the quality of the light being shone through it, the
thickness of the container and the degree to which the beer absorbs
light at each wavelength. With beer, we put the sample into a small
glass cell (cuvet or cuvette) and place this in a spectrophotometer
which shines a monochromatic beam of light through the cuvet and
measures its amplitude relative to the amplitude of a reference beam
which doesn't go through the cell. The relative amounts of light,
expressed as a percent, is a measure of the amount of light absorbed by
the colored materials in the sample (and the amount absorbed by the
cuvet which is compenstated for by first taking a reading with a cuvet
filled with distilled water). This is called the transmittance. In order
to convert transmittance data into a color we multiply the transmittance
values by the relative spectral intensities of the illuminating light
for which we want to compute the the color. A beer actually viewed
against illuminant C will look different than a beer viewed against
illuminant D50 (the standard for the graphics industry) and different
again agains illuminant D65 (used by Japanese TV set manufacturers to
get a brighter, if bluer, picture). If we have the absorbtion data we
can compute the perceived color for any illuminant whose spectral
distribution we know.
The next step in color calculation is to multiply each illuminant
corrected transmittance by each of the color matching function for the
particular wavelength. The twice multiplied tranmittance values (set of
three) are then summed and normalized resulting in three numbers. If the
color matching functions were for R, G and B we have three (tristimulus)
values for red, green and blue. If the color matching functions were for
X, Y and Z we have brightness information directly in Y and color
information in X and Z. x and y are calculated by normalizing X and Y (z
= 1 - x -y so it is not calculated) and the result Y,x,y is the
tristimulus color in CIE space. The new ASBC method for color analysis
does what I have just described here. The illuminant corrected color
matching functions are tabulated. The analyst takes the spectrum
measurements, multiplies by the CMF's and does the summations and other
math to end up with Y,x,y tristimulus values.
------------------------------
Date: Tue, 12 Sep 2006 18:36:55 +0000
From: "A. J. deLange" <delange-aj at zai.com>
Subject: Beer Color 2
Tristimulus specifications of beer color are good in the sense that they
tell you what actual color an observer would see given that he put a
glass of the same thickness as used for the lab measurements before an
illuminator of the same color quality. But they don't tell you what
color he will see if he looks at it in a different thickness glass
before a diffent light source. Tristimulus takes all the information
about the beer, contained in the spectral measurements, combines it with
data about the light source and boils it down into 3 numbers. The
fundamental information about the beer itself in in the absorbtion
spectrum. We can, in fact, adequately characterize the whole absorbtion
spectrum with 3 or 4 numbers but that's a topic for another time.
But at least we now get three numbers (from labs that use the
Tristimulus method) instead of the one from the older SRM method. While
larger breweries may be switching over to Tristimulus and recording it
in their internal records craft and home brewers will continue to use
the SRM and similar EBC method for some time to come. In the SRM (EBC)
method the sample is put in a one half inch (1 cm) cell and minus the
log of the transmittance, expressed as a fraction, measured at 430 nm
(i.e. 50% --> 0.5 --> 0.301) is multiplied by 10 (25). Minus the log of
the fractional transmittance is called the absorbtion.
From here on we will be talking mostly about absorbtion, not
transmittance. It is important to understand that the former is the
negative logarithm (to the base 10) of the latter. It is also important
to note that the transmittance is measured in percent doesn't meen that
it can't have values like 0.001% and that while many instruments will
only measure to A = 3 or 4 doesn't mean that you can't measure down to A
= 7 (if you have the big bucks for the fancy research instruments).
Where beer color comes from? Obviously from any elements or compounds
dissolved in the beer which absorb visible light and are present in
quantity high enough to absorb appreciable light. Clearly the thing that
contributes most to beer color are compounds formed in malting, in the
mashtun and in the kettle. Major among these are the compounds formed by
heat resulting in reactions (Maillard) between amino acids and sugars
which produce a bewildering array of colored compounds. Let's suppose
that a beer contains only three of these, a, b and c, and water and that
they are in concentrations Ca, Cb and Cc. Further we assume that they
don't react with each other to form new compounds (i.e. they are in
chemical equilibrium as all reacting took place during the brewing
process), that they don't react with water and that water does not
absorb light appreciably at any wavelength of interest. Beers law says
that the absorbtion at a particular wavelength for this beer should be
A0 = Ka*Ca + Kb*Cb + Kc*Cc where the K's are the absorbtion factors for
a unit path length for the particular compound at a particular
wavelength. There is a linear dependence on concentration for each
species and linear independence between species. As an aside here we
note that this is easily converted to the Beer-Lambert law by
multiplying by the path length L: A0(L) = L*Ka*Ca + L*Kb*Cb + L*Kc*Cc.
The concentrations are expressed in moles per liter. If we were to
double the amount of water in a beer by adding a volume of it equal to
the volume of the beer each molar concentration would be halved and
A1 = Ka*Ca/2 + Kb*Cb/2 + Kc*Cc/2 = A0/2
Thus for a beer which obeys Beer's law diluting by a factor F deceases
the absorbtion by the same factor. As an interesting aside it is easy to
prove that if diluting a solution by a factor F decreases the absorbtion
by F then EVERY substance in the solution must obey Beers's law.
Proof: Assume substance c does not follow Beer's law but rather the law:
Ac = Kc*Cc + Gc*Cc*Cc
Then a dilution by factor F gives AF = Ka*Ca/F + Kb*Cb/F + Kc*Cc/F +
Gc*Cc*Cc/F*F !=A0/F
We invoke Occam's Razor to exclude weird cases where the nonlinearity in
one substance is exactly offset by the nonlinearity of another in the
opposite direction and the concentrations are exactly the same.
------------------------------
Date: Tue, 12 Sep 2006 20:53:35 +0000
From: "A. J. deLange" <delange-aj at zai.com>
Subject: Beer Color 3
If you've labored through Parts 1 and 2, that's great. I promise that
the meat is coming. So now that it appears that Beer's law does apply to
beer (and it's easy enough to test a particular beer) how can we use it?
First the guy in the lab with a spectrophotometer that doesn't have the
range for some beer like Watney's stout (80 SRM) can dilute the beer by
a factor of 5 and get it down to 16 SRM. If he's using the SRM method
then that's all he has to do. Dilute, measure the SRM value and multiply
the measured value by the dilution factor. This is because SRM is simply
absorbtion scaled by 10. If he's doing the tristimulus method then his
task is harder. He must dilute, measure the complete absorbtion
spectrum, multiply it by the dilution factor and convert that to
transmission. He then uses the transmission spectrum with the color
matching functions to calculate the tristimulus for the full strength
beer (the answer will be that the beer is a very pure, very dark red).
Rather than dilute a beer to get its color within range of a particular
instrument one can simply reduce the path by using a narrower cuvet.
This relies on the Lambert half of the law and as with the Beer's part
one need do nothing but scale by the change in path length for
absorbtion based methods (SRM/EBC) but must scale absorbtion by the
ratio of the path of interest and the cuvet path, convert to
transmission and then apply the color matching functions to get
tristimulus. Note that this may be of interest in cases where the beer
does fall within the range of the instrument. If one measures in a 1 cm
cuvet but wants to know what the beer would look like at 5 cm depth he
scales the absorbtion spectrum by 5, converts to transmission and uses
the color matching functions with this new transmission.
Now what I'm really interested in here is the possibility that one might
be able to use Beer's law to estimate the SRM color of a beer by
dilution of a "standard" and visual comparison of that standard to the
sample beer i.e. no instrumentation other than a simple optical
comparator. The Fix's did something like this in the past and that work
needs to be revisited in terms of the possible redemption of Beers law
(and remember it is only potentially vindicated at this point). The idea
is that if you know Guiness is at 50 SRM and you can get its color
intensity to match that of a test beer at around 430 nm by diluting it
4:1 then the test beer is at 10 SRM. The catch is that the colors of the
diluted and test beers will not be the same though they should be
similar. As I recall I tried to do this in the past without much luck.
Looking through a blue filter may help as it is at the blue end of the
spectrum where the SRM measurement is taken. That is, however, the part
of the spectrum where the beer is darkest. I'll be digging out old
notes to see if there is new hope here and posting any results/conclusions.
Let me end at the beginning which I think was my declaration that Beer's
law doesn't apply to beer in the context of calculating beer color for
planning purposes. In that post I believe I said that one was unlikely
to get an accurate estimate by combining the published color values of
various malts because the published values use the Congress (EBC) mash
schedule and as a brewer doesnt use that he's unlikely to get the same
color in a real mash. Plus I didn't think Beer's law applied and perhaps
here it doesn't as we are talking about the colors caused by substances
which haven't yet been heated together. Thus all reactions/interactions
may not have taken place and the linear independence of color
contributing substances may still be in question. This would be the one
place where I still think the law's validity may be questionable.
------------------------------
End of HOMEBREW Digest #5056, 09/12/06
*************************************
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