Making Good Espresso
The espresso machine has a metal filter basket filled with finely
ground coffee which is called a shot. The espresso shot is then patted
or tamped down to compress the grounds into a dense puck. The shot is
locked under the brewer and then heated water is forced through the
fine grounds. The pressure of the tamping and the filtered water,
combined with how fine the coffee grinds are, will influence the
quality of the final espresso beverage. A double shot of espresso
should make 2 to 2.5 ounces of beverage in 20 to 25 seconds, and
should be about 160 to 165 degrees in the cup. This is generally
considered the recipe for a quality cup of espresso. An espresso
machine also has a steam wand that is used to froth milk for milk-
based espresso beverages like cappuccinos and lattes. Different
machines will vary in style, price, features, speed, and consistency,
and will produce different qualities of espresso and espresso
beverages.
http://www.askstar.com.cn/health/Buying-an-Espresso-Machine.htm
