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HOMEBREW Digest #5348
HOMEBREW Digest #5348 Wed 18 June 2008
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
Digest Janitor: pbabcock at hbd.org
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Contents:
Phenomenology and beer - pt 1 ("steve.alexander")
Kettle weight paradox ("Greg 'groggy' Lehey")
Re: Sanitizers (Tim Runnette)
Phenomenology and beer - pt 2 ("steve.alexander")
Fast Ferment Test (Kai Troester)
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Date: Tue, 17 Jun 2008 23:09:50 -0400
From: "steve.alexander" <-s at roadrunner.com>
Subject: Phenomenology and beer - pt 1
It seems Fred Johnson posts some tasty topic whenever I'm in the middle
of a travel or a time-crunch. I'm having more than my share of these
this year and I'll be missing the Cincinnati AHA this week as a result ...
> > Thanks to all of you who have contributed to this discussion. I
Let's not put a cork in this one quite yet.
Alexandre Enkerli writes
> > Well, honestly, as a social scientist and an artist, I can't really
> > say I share Fred's frustration over difficult or impossible to measure
> > characteristics. [...]
> > In fact, I often wonder why it seems important to *reduce* perception
> > to measurement, in the case of something which is meant to be enjoyed.
> > No offence intended, of course. Fred and others aren't at fault. It's
> > just that the perspective puzzles me.
The age of enlightenment was among other things an era of careful
observation and experimentation leading rather directly to the modern
ability to manipulate the physical world. Alan Watts popular writings
on philosophy describe "Western thought" (science) as a process of
breaking the world into smaller and smaller pieces with finer
resolution, but less relevance to the whole. This is true, but he
ignores the other half which is science drawing a much bigger
overarching "laws" from these tiny fractured observations. One
measures the rates that stones and feathers and apples fall, and
suddenly momentum, and gravity and the motions of the planets is
revealed. We observe the relation of pressure, volume and temperature
then sound and thermodynamics are accessible. One makes a few
observations about the volumes of gases produced in chemical reactions
and suddenly the chemical structure of matter is known. One makes some
careful measurements of the speed of light relative to the earth and a
deep view of the nature of light, and a complete explanation of
magnetism suddenly appears. These sorts of development, from
observation to generalization are startling and have had practical
import to the extent that modern life (and about 30% of the population)
would be impossible without them.
So how could it be that reducing observation of sensory perception (or
anything else) is not of paramount importance, if we wish to understand
it ? It is demonstrably the most successful model for forming an
accurate and functional view of the physical world. Sorry - but I find
the "anti-science" attitude that prevails in the recent few decades (and
I don't think that is where Alexandre was heading) obnoxious.
Understanding the causes of a subjective experience doesn't reduce the
experience, but it may reveal how to create or extend that experience.
As brewers we are clearly producing a "designed" product and so we would
like to know how the design relates to the experience.
So back to the current puzzle.
If anyone cares for an amusing intro .... In sci-fi classic 'Dark Star'
an astronaut attempts to disable a smart bomb by teaching it
phenomenology. http://www.youtube.com/watch?v=EvcfPVGY-ck
Phenomenology need not be so crippling.
We take a beer sample and we apply it to a human sample and we elicit a
qualitative description. What just happened ? Is it useful ?
We have good reason to believe that humans are generally physiologically
similar, so they may experience the beer sample with a similar
subjective experience. Of course we also have good evidence of wide
variations ... many mushrooms for example taste bitter to certain ppl
but not others based on their specific genetics. Many ppl (tho' a
minority of European descent) are so called "super tasters" with a
reported higher density of papillae on their tongues. Certain internal
states or combinations of stimuli can result in odd experiences (e.g.
certain generally phenolics make tea taste LESS bitter !). Furthermore
we can probably never record the subjective sensation directly; tho'
EEGs and PET scans are a step closer. We must use indirect measures.
We have all learned to utter similar qualitative descriptions(QDs) when
the same stimulus is applied. We have learned to say "sweet" in
response to sucrose, and "salty" to sodium chloride, but this doesn't
necessarily mean our subjective experiences are the same. So we have a
mapping from objective stimuli to some subjective experience then back
to a QD with some pretty good correlation. That regularity of
stimuli->QD mapping is weaker down across "cultures" and varies based
on learned results. A group of trained beer judges might all utter
"diacetyl" in response to the same stimuli - but an untrained taster
might produce an entirely dissimilar QD. Of course the QDs produced are
based on experience and local convention; British wine writers like to
compare red wines to "cassis", but fresh cassis berries aren't widely
available in N.America. N.Americans may describe sunstruck ales as
"skunky", but it's unclear how this QD is interpreted in Eurasia.
We also have "hedonic scales". A majority of beer judges might frown
and downgrade a beer with diacetyl, while others might smile and argue
that a certain level is expected in certain styles. We have cultural
divides on the hedonic scale - the bland Japanese diet vs the spicier
diet of India for example predisposes the preferences of individuals.
We have idiosyncratic tastes - some ppl enjoy oxidized wines or other
oddities. Children generally reject bitter foods while adults can enjoy
these - and this may have survival value.
(cont)
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Date: Wed, 18 Jun 2008 17:43:01 +1000
From: "Greg 'groggy' Lehey" <grog at lemis.com>
Subject: Kettle weight paradox
I've just bought myself a couple of large aluminium stock pots for use
as a mash tun and wort kettle. First thing I did was to confirm
volumes and such, and while I was at it, calculated the weight of the
pot, mainly to check my measurements. But it didn't even come close
to the real weight. Here's an extract from my online diary
(http://www.lemis.com/grog/diary-jun2008.php#17 :
The other thing of interest is the weight of the pot, since it enters
into the thermal calculations. One option is to measure the volume
and calculate it. For the 100 litre pot I get the following details:
Thickness 0.4 cm
Outside diameter 53.0 cm
Inside diameter 52.2 cm
Height 45.3 cm
Area base 2206.2 cm2 (outside diameter2 / 4 * pi)
Volume base 882.5 cm3 (area * thickness)
External volume 99940 cm3 (area * height)
Internal volume 96946 cm3 (inside diameter2 / 4 * pi * height)
Volume of wall 2994 cm3 (external volume - internal volume)
Total volume of pot 3876 cm3 (volume of wall + volume of base)
Weight of pot 10465 g (total volume * 2.7, density
of aluminium)
The problem is, the pot only weighs 5.8 kg, including the handles
which I didn't account for here. Take them away and it's reasonable
to assume that I have calculated exactly double the real weight. The
same applied for the other pot. But how? I can't see anything wrong
in my calculations, and though my measurements of diameter and height
might be out by a millimetre or two, I measured the thickness with
vernier calipers, and they agree with the specifications. Put it to
people with time on their hands, the ones on IRC, and they all came
up with the same answer within the constraints of rounding.
So what's the answer? Hollow pot? Unlikely. Tapering thickness? It
would need to taper to 0 to explain this discrepancy, clearly not the
answer. Different alloy? It would have to have a density of 1.35 or
so, and alloys that light are expensive. The pots weren't. I'm still
puzzled.
Does anybody have an insight?
Greg
- --
Finger grog at Freebsd.org for PGP public key.
See complete headers for address and phone numbers.
------------------------------
Date: Wed, 18 Jun 2008 06:57:00 -0500
From: Tim Runnette <trunnette at mac.com>
Subject: Re: Sanitizers
Thnx for posting the archive link Tom. Great episode. Below is the
link to the Five Star Chemical site. It has product info and some
other homebrew info.
http://www.fivestarchemicals.com/brew.asp
Cheers,
Timmy
------------------------------
Date: Wed, 18 Jun 2008 10:32:29 -0400
From: "steve.alexander" <-s at roadrunner.com>
Subject: Phenomenology and beer - pt 2
So food/flavor scientists have taken this issue to extremes. I would
suggest that anyone interested seek out the writing of "J.R.Piggott" of
the University of Strathclyde, Glasgow. I have a copy of his (editor)
"Understanding Natural Flavors" and also his "Science and Technology of
Whiskies"; both are very difficult to find. Piggott seems to publish in
a range of flavor/taste/food journals, but also occasionally in JIB with
respect to beer and whisky. I don't have a copy of Piggott's "Sensory
Analysis of Foods" which probably has a better and detailed description
of the methods.
Food scientists often use a panel of expert tasters and it is expected
(and tested) that these panels have consistent stimuli/QD mappings.
It turns out that we can transform the stimuli/QD mapping of individuals
or groups into a normalized form in a very clever way. You give an
individual a set of samples and have then produce a weighted "short
scale" of terms and values for each (one beer rates 3 on sweetness and 7
on bitterness and 2 on floral aroma and ...) . The terms the user
chooses form non-orthogonal axes that can be mathematically transformed
to correspond to others terms or more usefully transformed to match the
known composition differences of the stimuli. So QDs can be
"corrected" or normalized in a sense. Your "oaky" becomes my 0.5
phenolic + 0.4 vanilla + 0.1 harsh.
Now when it comes to the hedonic scales (what we actually like/enjoy)
"principal component analysis"(PCA) is often used. Here is a short
paper on the topic, www.snl.salk.edu/~shlens/pub/notes/pca.pdf and
the first few sections give a very readable description. It's based in
the Karhunen-Loeve transform, that I first came in contact with in the
realm of pattern recognition. The PCA can be thought of as a form of
pattern recognition where we normalize the statistics of each dimension,
find and reduce the most significant axes in order. There is a
linearity assumption that clearly doesn't rigorously apply to
taste/flavor/hedonic rankings.
So there are ways to overcome the subjectivity hurdle - or at least push
it back into the corner.
==
Back closer to the real world and specifically to mouthfeel/body/viscosity.
I tend to personally agree with Dave Harsh that mouthfeel encompasses
the non-flavor, non-aroma components, and the "body" or similar more
specific term is the topic. It is clearly (IMO), related to
viscosity, but there are as Matt Baums suggests other factors at work.
I personally do think we want to consider things like the "electronic
nose" (Google it) which are attempting to replicate the human olfactory
system, but extended to measure other food parameters like "mouthfeel.
That doesn't mean it would replace humans in judging, but it could help
us understand ourselves better. The whole idea of segregating beers
according to style in
Kunze (a book with too few references listed) divides the topic into
"Palatefulness(body)" and also "Tingle" . Tingle is from CO2, but also
impacted by pH (lower pH, more tingle). The body factors are, according
to Kunze related to alcohol content and residual extract, but also dark
more highly cured malts, high MW proteins (10k-100k daltons) . Kunze
specifically states that overmodified malt leads to poor body. And long
mash rest 45C-55C leads to low tingle and poor foam. Also ... "addition
of gypsum [calcium sulfate] or calcium chloride to the brewing water
also increases the sensation of mellowness and body on drinking.
Residual alkalinity and acidification produce more full bodied softer
beers". My reading between the lines has Kunze pointing to high MW
protein and calcium ions along with residual extract(dextrins) & alcohol.
My opinion is that protein (type) and carbonation level are extremely
important to body. I think we've all had a keg in the fridge over an
extended period and early-on the foam and head are huge and the body
correspondingly high, but over time protein drops, the beer clears, and
at the same carbonation level the head declines along with mouthfeel.
Wheat beers, with a notch more protein and high carbonation often have
great palatefulness. Hops has a considerable positive impact on foam and
some APAs seem to have enormous body in the CO2/foam-like sense of
palatefulness.
Another example is Guinness which obviously has low residual extract,
perhaps higher protein from the roast barley and modest alcohol, but the
co2/nitrogen/protein give this beer an enormous initial sense of body.
Degassed Guinness OTOH is quite thin and lacking in body.
Dextrins are also clearly important; but I get a hedonic negative vibe
from excess dextrins as I expect a bloated tummy as a result.
Another example for consideration are beers with oats or sometimes rye
or other tertiary brewing grains. It seems that the glucans create a
silky, almost oily mouthfeel that has a clear "body" impact.
Fwiw tests among coffee tasters show that the sensation of body in
coffee is almost directly related to the extracted oil content. Of
course finished beer has almost no oils.
-s
------------------------------
Date: Wed, 18 Jun 2008 17:30:14 -0400
From: Kai Troester <kai at braukaiser.com>
Subject: Fast Ferment Test
I have been using the a fast ferment test for a while to determine
the limit of attenuation for the beers that I brew and was introduced
to this test by German brewing literature (home brewing as well as
commercial brewing). While I find it very useful to know the limit of
attenuation, especially when brewing lagers or higher gravity beers, I
have not heard about it in the American home brewing community.
The idea of the fast ferment test is to take a sample of wort and overpitch
it with yeast (preferably the yeast that the batch is fermented with).
Together with fermenting it warm (70+ F is great) this should result in a
complete fermentation of all the sugars that this particular yeast can
ferment (there is actually only a small difference in the wort sugars that Ale
and lager yeasts can ferment). The resulting attenuation of this fermentation
sample is the limit of attenuation of the wort and provides an upper
boundary to the attenuation that can be expected from the main fermentation.
It only depends on mashing and thus provides a nice separation between the
mashing and fermentation contributions to the final beer attenuation.
Fermentation characteristics like yeast strain, pitching rate, temperature
and so on will determine how close the yeast will get to the limit of
attenuation and the residual fermentable sugars become an important part of
the character of the beer.
A more comprehensive write-up on this test can be found here:
http://braukaiser.com/wiki/index.php?title=Fast_Ferment_Test
Is this test known among American home brewers and was determined to be
unreliable or to much work? Why don't we teach new brewers this test?
I would have at least expected it in more technical home brewing literature.
While not really useful for a brewer who is happy with the attenuation of
his/her beers, it provides very useful information for troubleshooting
attenuation of a beer as it will tell you if your problem lies in mashing
or in fermentation.
Kai (Massachusetts)
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End of HOMEBREW Digest #5348, 06/18/08
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