Most commonly, an Americano is used when one orders a brew-coffee
sized drink from an espresso bar.
Americanos—particularly short, long-black-style Americanos—are also
used within artisanal espresso preparation for beans that produce
strong espresso. This is particularly used for single origin espresso,
where many find that undiluted espresso shots can prove overpowering;
and with lighter coffees and roasts not generally associated with
espresso, such as beans of Ethiopian or Sumatran origins.
For this preparation, generally a ratio of 1:1 espresso to water is
used, to prevent excess dilution, with the espresso pulled directly
into a cup with existing water to minimize disruption to the
crema.
The hot water can be drawn directly from the same espresso machine
that is used to brew the espresso, or from a separate water heater or
kettle. Using the same heater makes a second one unnecessary, and the
water can be drawn directly into the glass, either before (for a Long
Black) or after (for an Americano) the espresso. Some espresso
machines have a separate hot water spout for this purpose, while on
others, the steam wand dispenses it. Using a separate water heater is
more practical in a commercial setting, as it frees the machine for
other baristas, avoids disrupting the brew water's temperature, and
reduces wear on specialized equipment.
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