HomeRoast Digest


Topic: Espresso science (9 msgs / 280 lines)
1) From: sci
I'll defer to your wisdom on this. I'm nowhere near a rocket scientist so
please help.
How can you get steam (which requires temps above 212 at MSL) under 9 to 15
BAR and not have a temp over 212F? Does high pressure increase temps and
condense the steam/gas back into a liquid which gets cooled as it travels
through the portafilter and out?
Somewhere in that thar portafilter, sumpthin's  over 200F.
Maybe this is why I just go to a shop for 'spro. I have no way to control
temperature on my machine except to turn it on or off. So who knows how hot
it is. You can't even stuff a thermo in there to measure it.
Ivan
++++++++++++++++++++++++++++++++++
Date: Mon, 16 Jun 2008 10:00:38 -0400
From: Allon Stern 
Subject: Re: [Homeroast] AP "Espresso"
To: homeroast
Message-ID: 
Content-Type: text/plain; charset-ASCII; delsp=yes; format=flowed
On Jun 15, 2008, at 8:22 PM, sci wrote:
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Higher than boiling temperature steam forced through the coffee?!  ur
doin it wrong.
Espresso is made with hot water, right around 200 degrees.
-
allon
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2) From: Ira
At 10:28 PM 6/16/2008, you wrote:
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All real espresso machines have pumps and the brew pressure is 
independent of temperature. I could pull shots with cold water if I so desired.
<Snip>
Maybe, or maybe not, depends how hot I want it. and where I set the thermostat.
Ira
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3) From: Tom Ulmer
Wisdom is a highly speculative term and should be disregarded from the
following.
Your assumption is the pressure used for extraction is produced from the
boiler vessel. While this may be true in some situations, a better method to
create the pressure would be to use a pump. The function of controlling
temperature at the portafilter is wholly dependant on design and a working
knowledge of such. You could measure the temperature of the water as it
reaches the portafilter if necessary for reference if so inclined.

4) From: miKe mcKoffee
Depending on the specific type espresso machine you can in fact end up with
over 212f shot temp if proper shot temp management is not observed. From
idle if I just walked up to my Bricoletta and pulled a shot temp would start
around 220f! Yet I consistently pull shots at the temp I "want" anywhere
from 196f to 208f on demand usually within +/- 0.5f of my desired target
temp. Different methods are used for different machines. Much has been
written about how. Spend some time, copious time, onhttp://www.home-barista.com/if you wish to educate yourself.
Pacific Northwest Gathering VIIhttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must">http://home.comcast.net/~mckona/PNWGVII.htmKona Konnaisseur miKe mcKoffeehttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
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5) From: Tom Ulmer
When you say shot temp are you referring to the resulting shot? 170-180=
F
is the range I look for my tastes and apparatus.

6) From: miKe mcKoffee
I'm referring to the puck shot temp which is the industry standard usage of
the term, as approximated measured calibrated via Scace Thermofilter. I've
never measured the resultant pull temp in the demitasse which would be
hugely dependent on the type of demi and specific temp demi pre-heated to.
Calibrating by taste IS the ulitimate guide.
Pacific Northwest Gathering VIIhttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must">http://home.comcast.net/~mckona/PNWGVII.htmKona Konnaisseur miKe mcKoffeehttp://www.mcKonaKoffee.comURL to Rosto mods, FrankenFormer, some recipes etc:http://www.mckoffee.com/Ultimately the quest for Koffee Nirvana is a solitary path. To know I must
first not know. And in knowing know I know not. Each Personal enlightenment
found exploring the many divergent foot steps of Those who have gone before.
Sweet Maria's List - Searchable Archiveshttp://themeyers.org/HomeRoast/=
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7) From: Alchemist John
Steam is not what is used to pull espresso.  That is where you are 
going afoul of understanding.  Espresso machines can steam milk and 
the like, but the water used (in general) is as others are saying - 
200-208 F pumped through (not pushed by steam) via a pump.  Only 
'steam toys' or moka pots use super heated water (steam or high 
pressure water over 212).  Those give you a different animal than espresso.
At 22:28 6/16/2008, you wrote:
<Snip>
John Nanci
AlChemist at large
Zen Roasting , Blending & Espresso pulling by Gestalthttp://www.chocolatealchemy.com/Homeroast mailing list
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8) From: raymanowen
"Spend some time, copious time, on [home-barista] if you wish to educate
yourself."
OK, thanks. I'll do just that.
A design had come to mind in which the packed grounds are subjected to a
pre-infusion partial vacuum, to be replaced by a charge of hot water then
pressure, per solenoids and pump.
As you all know, the book of what I know about espresso machines is far
outweighed by the Dunno Book. "An Espresso Machine" and some insight and
care of the brewing process and grounds preparation would put an end, I
thought, to any possibility that espresso was any more than a carefully
controlled misteak. A Yuppie drink suited to the *$ treatment.
Unfortunately or not, I was rong again. I liked about 3% of my shots at
first, and tried harder to make more good ones. From Mokha pot to steamer to
cheap pump, they found new homes and I got a less cheap pump that reminded
me of Arlene Dahl
With any brewing method and machine, the first fundamental is- you
absolutely have to keep it clean, otherwise some uncontrolled variation is
being introduced to the flavor of coffee infused by hot water. Random coffee
has never been my goal, hence, a built-in Hotsy steam group cleaner to blast
out remaining grounds after removal of the filter handle.
All brewing methods suffer from the uncontrolled variations introduced by
toy grinders, whether they have new burrs or not. The workarounds are
effective, but a little involved.
In my opinion, a machine that can't stand its own operating pressure for
cleaning is from Junque, Inc.- others' opinions notwithstanding. I respect
them, I just differ. Why I design.
Cheers, Mabuhay -RayO, aka Opa!
Got Grinder?
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9) From: Ed Needham


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