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re: coffee drink
15 nov 2003
lorenzo l. love  wrote:

>bob ward wrote:

>>>espresso isn't magic. hot water forced through the right kind of ground
>>>coffee under pressure makes espresso. the trick is in the right kind of
>>>ground coffee. very dark roasted and ground to a powder like consistency...
>>>with the right type of coffee, espresso is very easy to make with
>>>an inexpensive machine. 
>> 
>> now you're making yourself clear.  you define espresso as the product
>> of a $30 coffeepot, and anything else must not be espresso by your
>> definition.
>
>still can't muster up a logical argument why it takes an expensive 
>machine to make espresso, can you?

here are some other opinions...

~~~

from http://www.americanconnoisseur.com/libations/espressoarticle.html

home espresso essentials:

what every espresso lover should know

"the key to perfect espresso is a precise combination of coffee, water,
temperature, and pressure, said sebastiano pagano, president, nestle' coffee
specialties usa, inc. "failure to meet optimal conditions for these
components can ruin the espresso."

in choosing a machine, the first step is to remember that true espresso
requires hot, not quite boiling water. "boiling water or steam burns
coffee's delicate essences," said mr. pagano. "espresso machines should
generate an ideal water temperature of 187 degrees to 196 degree fahrenheit."

next, consider how much pressure the machine delivers. eight bars of
pressure is the minimum required to make a true espresso (one bar of
pressure is equal to 14.51 pounds of pressure per square inch). speed is
also critical. the machine should produce an espresso within about 20 seconds:
if shorter, the espresso lacks body; if longer, the result is too bitter.

when everything is working perfectly, a golden layer know as the "crema"
sits atop the espresso. the crema seals the espresso's aroma in the cup.
"crema is the ultimate test of espresso quality," said mr. pagano. "espresso
without the crema is just strong coffee, and probably poor coffee at that."
consumers can choose from three basic types of espresso machines: the
boiler, the pump/boiler, and the pump/thermoblock system. the boiler method,
while relatively inexpensive, does not generate optimum pressure and often
heats water to too high a temperature. the pump/boiler method, although
preferable to the boiler, allows too much fluctuation in temperature and
pressure.

the pump/thermoblock heating system is the most reliable choice, providing
optimum temperature and pressure at consistent levels. the nespresso system
features a microchip-monitored pump that extracts espresso at 11 to 15 bars
of pressure. nespresso's thermoblock heating element maintains a continuous
water temperature, controlled by a thermostat, within the ideal range of 187
to 196 degrees fahrenheit.

from http://www.coffeekid.com/espresso/minifaq

coffeekid - the espresso minifaq1. what exactly is espresso

today's espresso is a 1.25oz - 1.75oz beverage that is brewed under the
proper conditions of 190-200f water, at least 130 psi of pressure which
would force said water through finely ground fresh coffee, extracts more
oils, aromatics, and flavor than any other coffee brewing method. a very
opaque, thick and dark liquid, capped by red-golden dense froth, also known
as crema is the result...

4. are there any concrete "givens" for espresso?

tough question. short answer is no. but a slightly longer answer involves
the following facts, or "givens":

italians in italy invented espresso

italians in italy improved espresso and brought in 9 bar production

italians in italy by and large consider espresso part of their daily routine

a normal single espresso is 1.5 us fl oz, +/- .5 ounce

a normal ristretto is 1 us fl. oz, +/-.25 oz

a normal cappuccino is 1/3 espresso, 1/3 steam milk, 1/3 froth

a normal espresso is poured in 25 secs, +/- 5 seconds

a modern day espresso must be produced in a pump or piston or lever machine
capable of producing roughly 9 bar of pressure

a normal espresso uses 7 grams of ground coffee, +/- 2g.

a normal espresso is brewed with 93 c water +/- 3c

a good espresso must have crema.

these are more or less accepted facts, but even amongst them you can see
there is a variance (all the +/- stuff)...

9. is crema really all that important?

yes

anyone who tells you that a good shot can be built without crema is fooling
themselves. crema is one of the primary indicators of a good espresso shot.
this isn't to say that every shot with crema on it is good - far from it.
but i am saying that every shot that doesn't have crema on it is a bad shot.

crema also serves other purposes besides being an indicator. crema contains
a lot of aromatics, which influence how your mouth tastes the espresso - the
olfactory sensors in your nose will register along with the tastebuds on
your tongue. crema also acts as a partial insulator for the beverage,
helping to keep it hot. and it has its own unique taste that adds to the
overall shot taste.

with all the above said, understand there are different types of crema, but
only one good type. there are many machines on the market today with "crema
enhancing devices". these produce what i consider false crema, the type that
dissipates rapidly and barely hangs to the side of your cup. i am also more
and more convinced that they degrade the espresso beverage taste. i base
this on my increasing experimentation and testing of espresso machines with
crema enhancers in place. i feel they create excess bitterness in the cup,
and produce a light beige type crema that is definitely false.

real crema, produced with a real machine using no "enhancer" tricks is rich,
thick, sticks to the side of the cup, and lingers right down to the last sip
and beyond. the color is dark golden - red - brown, usually with some sort
of tiger flecking patterns on the top. a sign that your shot is possibly
amazing :-)

~~~
so... from an objective point of view, we might define espresso as coffee
made with water at 93 +/- 3 c, with the coffee spending 20 +/- 5 seconds
under a pressure of 9-11 bars, and we might say it must have a crema layer.
we might say the object is to sufficiently heat and dissolve certain coffee
components but not others with this combination of pressure and temperature
and residence time.

the grind might not matter much for the diffusion process, if the water has
many time constants to penetrate into the rather small coffee granules, but
the particle size and packing pressure and coffee container shape could be
important in producing a "nozzle" outlet with a hydraulic resistance that
allows the process above.

with too much resistance, the pressure might have to be more than 11 bars 
to complete the process in 25 seconds, or the process might take longer than
25 seconds, possibly overcooking desirable coffee components and extracting
undesirable elements from the coffee. too low a resistance might make the
pressure less than 9 bars, in a 15 second process, or reduce the process
time to less than 15 seconds, undercooking or failing to extract desirable
elements from the coffee.

it seems possible for lorenzo to produce perfect espresso with a $30 machine.
he might use a stovetop machine with a gas stove or a propane or acetylene
torch, and move the machine closer to the fire as the water flows out of the
boiler in a very particular and possibly interesting acrobatic manner as
a function of time that exactly produces the process above. do stovetop
machines make 9 bars, or would they explode or pop their gaskets or pressure
plugs before that? it could be hard to change the water pressure much over
20 seconds without changing the temperature much, except with a very hot fire
or a very large boiler surface exposed to the fire. we could quantify this.

this might be easier with a pressure gauge and a very large boiler compared
to the espresso volume, so the pressure doesn't change much as the smaller
volume of water flows out, but larger pressure vessels need to be stronger,
and they can be dangerous, so lorenzo might use a low-pressure constant temp
boiler and a lever pump to pressurize a smaller volume of water more safely
and accurately.

so... we seem to have a boiler, a temperature gauge, a pressure gauge, and
a lever pump. sound familiar?

i use a french press, but i'd like one of those brass or chrome machines :-)
i have a little braun electric boiler with no pump, but it's iffy. coffee
grind and packing and timing are critical. too loose, weak coffee; too tight,
popped gasket. the boiler with an electric pump seems like a better idea,
but it's more expensive ($120) and the pump will wear out, and the lever
version seems like more fun, albeit more expensive.

nick




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