• Espresso is not a type of roast but rather an extraction process where hot, not
boiling, water is forced under high pressure (9 bars of pressure) through coffee
that has been finely ground.
• Espresso machines come in various sizes. In most commercial applications, an
espresso machine has two boilers…one for boiling water to produce steam for the
steam wands for steaming milk, and the other for producing highly temperature regulated
water (approx. 198 to 220 degrees) for the production of espresso.
Home units often have only one small boiler with a special heat exchanger for
regulating its water temperature.
• Espresso is chemically complex and volatile with an immediate shelf life of only
about 30 seconds after being pulled. Within seconds, a shot is susceptible to
oxidation and loss of temperature.
• A one-fluid ounce shot of espresso (with 50 mg of caffeine) has about half the
caffeine of a standard six-fluid ounce cup of American-style drip coffee, which
varies from 80 to 130 mg.
• A Barista refers to one who has acquired a certain level of expertise in the
preparation of espresso based beverages. Since espresso and coffee production is
complicated and can be easily fowled due to human error, this training is essential
to ensure a Barista can produce the best possible beverages possible.
There are eight steps to producing a proper espresso shot:
As a general rule, espresso shots should exit the porta-filter with the consistency of honey
with as little breaks in flow as possible. In other words, it should have the same look as a
There are eight main steps to producing excellent quality espresso.
Every step is critical to the production of each shot. In general, if your espresso is not pouring well, one of these steps needs correction.
- Fresh Whole Beans: the freshest beans produce the freshest espresso. Beans
should be fresh ground immediately before production.
- The Proper Grind: espresso beans change size with the humidity and
temperature of your surroundings. These changes cause the beans to grind
differently. Properly adjusting your grind is imperative for quality shots.
- Tamping Pressure: fresh grounds should be tamped at approx. 40 lbs of pressure. If they are not tamped properly, it will affect how the pressurized water flows through the grounds which will affect the shot times, the crema formation, and the flavor profile of the espresso.
- Fresh Clean Water: clean filtered water is imperative to clean tasting coffee.
One wants to taste the coffee, not the chemicals in the water.
- Water Temperature: water must be at the proper temperature. Water that is too
hot will burn the coffee, while water that is too cool will not react properly with
the grounds causing a poor taste profile.
- Water Pressure: hot water is injected through the coffee under pressure,
measured in bars. The water reacts with the coffee producing a ‘shot’ of coffee
with crema, the foamy substance on top of the coffee. Nine bars of pressure are
required to properly extract an espresso shot. A barista should monitor their
espresso machine to ensure shots are consistently pulled at nine bars of pressure.
- Shot Timing: If ground and tamped correctly, shots should take anywhere from
18 to 30 seconds to produce a shot volume of approx. 1 to 1.25 ounces. If a
ristretto is pulled, the shots are manually stopped at half that time to produce a
clean, less bitter espresso with less caffeine.
- Preservation of Crema: the crema, or the foam on top of every shot, holds the
delicious oils of the coffee and is responsible for over 80% of the coffee’s flavor.
You must preserve the integrity of the crema at all times by such tasks as never
pouring shots over ice, never pouring hot water over the shots, or using shot
glasses which trap some of the cream when the shots are transferred.
Espresso shots should, in general, take 18 to 30 seconds to produce. Humidity and your surrounding temperature effects the beans, which affects the grind, which effects how the water flows through the grinds, which affects how long the shot will take. Grinder adjustments must be made to ensure shots are consistent and of high quality. Typically, if the shots are flowing too quickly, your grind is too large and you must make your grind finer. If they are flowing too slowly, your grind is too fine trapping the water so you must make your grind larger to allow the water to flow quicker.