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What Is Espresso; Overextraction And Underextraction; Before Brewing: The Elements Of A Great Espresso; Fresh Coffee Beans - KitchenAid Artisan 5KES100 User Instructions

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Espresso began as an attempt in the 1800s to quickly brew
coffee on demand, by the cup. The goal was to serve the
freshest, most flavorful coffee possible and avoid the burned,
stale taste of coffee kept warm on a stovetop. To speed the
brewing process, coffee pioneers struck upon the idea of
forcing water through the grounds under pressure. Steam was
initially used to supply the pressure, followed by compressed air,
lever operated pistons, and finally, the electric water pump.
Through the decades, the elements of espresso brewing were
Brewing great espresso takes an understanding of what actually
winds up in the cup when coffee is exposed to water. Roughly
30% of a roasted coffee bean is made of water soluble
compounds. 20% of those compounds dissolve fairly easily,
while the remaining 10% take a little more work – which is a
good thing, because that less-soluble 10% is acidic, bitter, and
generally unpleasant. The goal of all coffee making is to extract
the easily dissolved oils and compounds while leaving the rest
in the grounds.

Before Brewing: the Elements of a Great Espresso

Before the espresso machine is even plugged in, you'll need
several elements to produce great coffee.

fresh coffee Beans

Great coffee can only come from fresh coffee beans, properly
roasted. Many baristas recommend buying beans roasted no
darker than a medium roast, the color of which appears as an
even chocolate brown. This roast preserves the natural sugars
and flavor of the bean, which sets the stage for excellent
espresso. A medium roast is the darkest a bean can be
roasted without oils developing on the surface.
Darkly roasted beans – which appear dark brown or nearly
black – look great, but the extra roasting overwhelms the more
delicate coffee flavors and caramelizes any sugars. A heavy
"roasted" coffee flavor, often bitter and sharp, will predominate
with a dark roast.
To preserve the freshness of coffee beans:
Keep beans in an opaque, air-tight container and store them in
a cool, dry place. Refrigeration is not recommended, as
condensation tends to form on the beans whenever the
container is opened. Freezing can help preserve beans stored
for an extended period, but it will also impair flavor.

What is Espresso?

overextraction and Underextraction

tested and refined to produce the standards we have today:
one cup (30 ml) of true espresso comes from exposing 7 grams
of finely ground and packed coffee to 90–96º C water under 9
bars of pressure. In a brief 25 seconds, most of the highly
flavorful coffee aromas and oils are extracted, while the more
bitter compounds and off-tastes are left behind.
When the ground coffee is fresh and the brewing is done
well, the pressurized brew water emulsifies the coffee oils into
the golden foam called crema, which crowns the espresso with
ultimate flavor and aroma.
If ground coffee steeps in water too long, all the soluble
compounds will be extracted, which makes for a very bitter
brew. This is called overextraction. The opposite of overextraction
is underextraction, which occurs when coffee is not exposed to
the brew water long enough, leaving the essential flavors and
aromas locked in the grounds. Underextraction results in coffee
that is weak in taste.
Whether brewed coffee is overextracted, underextracted, or
just right depends on several factors, including the ratio of
coffee to brew water, the fineness of the grind, the brewing
temperature, and the length of time the water is in contact with
the coffee. All these factors are either directly or indirectly
affected by the barista's technique.

Great tasting Water

An often overlooked element of great espresso is the brew
water. If you don't enjoy the flavor of your tap water, don't use it
to brew espresso – use bottled, purified water instead. Since it
doesn't take long for fresh water to acquire a "flat" quality and
taste, it's also a good idea to change the water in the tank often
and refill the boilers after a long period of non-use.
Do not use mineral water or distilled water – they can
damage the espresso machine.
the right Grind – and Grinder
Espresso demands a very fine, very consistent grind. Blade
grinders and inexpensive burr grinders usually fall short when it
comes to producing the grinds needed for outstanding
espresso.
The best espresso requires a quality burr grinder, like the
Artisan™ Burr Grinder. A good burr grinder will maximize the
flavor and aroma of espresso by producing an extremely
consistent grind with very little frictional heating.
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