CoffeeEspresso Machine 101 - a Guide to Making Espresso
A person who operates an espresso machine for a living is called a barista. Similar to artisan baking, the knowledge and skill required to make the best espresso beverages is considered to be a craft in Italy. Increasingly, baristas in America are being recognized as such too.
When one makes a shot of espresso, it is called pulling a shot. This is because the traditional espresso machine that is used requires the barista to pull a long handle in order to produce a shot. For a single shot of espresso, between 7 and 10 grams of finely ground (almost a powder) coffee is needed. For a double shot, between 12 and 18 grams are used. A single shot of espresso is 30 ML of liquid, a double shot is 60 ML.
Before the espresso can be brewed, it must be tamped. To tamp espresso, the barista must compress the coffee gounds into a dense puck. When the brewing process starts, nearly boiling water (90 degrees Celsius) gets pressured though the coffee. Espresso is the result.
If the water is too cool, the espresso will be sour. If the water forced through the coffee is too hot, the beverage will be bitter. The best espresso machines control the temperature of the water, ensuring that it is always within a couple degrees of the ideal temperature.
This brewing process extracts and emulsifies the oils in the ground coffee, producing a thick, rich beverage. A shot of espresso takes approximately 25 to 30 seconds to go through the ground coffee puck and into the waiting cup sitting below the espresso machine. This is an ideal zone, and water pressure, tamping and fineness of the grind can all have an effect on this time zone. The cup that one drinks espresso out of is called a demitasse cup, and is best when pre-heated.