Glossary

This collection of illustrated definitions will clarify the specific functions of espresso machine parts and enhance your barista vocabulary.

Basket
Coffee grounds are held in place during the brewing process by a metallic basket with tiny holes in its bottom from which the liquid escapes the brewing chamber. Espresso machines usually come with a single-shot and a double-shot basket.

Brewing Time
A double shot of espresso will only take 25-30 seconds to fill two 1 oz. cups. If one brews for a longer period, a bitter flavor will end up in the espresso.

Brush
Cleaning the espresso machine between each shot is important in order to keep it running smoothly. Using a brush to clean the group head and the steam wand will ensure the best flavor in your cup.

Built-in Grinder
A built-in grinder will crush and tear only the required amount of coffee beans to prepare the immediately desired brewed coffee. It consists of two revolving disks milling the beans to a consistent ground size. Resulting coffee has maximum freshness and aroma.

Boiler Single/Double
A single boiler heats water for both the brewing and the steaming processes. Because they don’t occur at the same temperature, one has to allow time for the boiler to heat some more between the shot being pulled and the milk being frothed. A double boiler has separate reservoirs, each at the appropriate temperature, enabling simultaneously pulling a shot and frothing milk.

Crema
Depending on the brewing process, crema is a layer of pale to reddish brown foam that forms on top of the well-brewed espresso shot.

Descaler
Available in the form of powder, pods or descaling solutions, this chemical product should be used every 6 months to remove mineral deposits such as lime scale from the tank, boiler and pipes of the espresso machine.

Doser
A doser automatically measures and releases the right amount of coffee grounds for a pre-determined shot of espresso: 7-9 grams for a single shot, 14-18 grams for a double shot.

Flow Sensor
This sensor automatically sends a signal that interrupts the water flow when the preset amount of coffee has been reached.

Gasket
Especially in the brewing chamber, the gasket is a rubber ring that prevents hot water, steam and coffee grounds from overflowing, and keeps the pressure constant during the brewing process.

Group Head
This chamber is where the coffee grounds are actually being brewed. It is pressurized and sealed when the basket is put in place. The espresso comes out through a double-faceted fixture allowing a double shot to be simultaneously poured into two cups.

Hook to a Water Line
A typical espresso machine requires the user to manually fill a water tank as the first step of preparing an espresso. However, with a higher-end model, it is possible to directly hook it onto a water line, thus eliminating the need to fill the reservoir and the risk of burning the element in case the machine runs out of water.

Long
This term refers to a 2 oz. shot of espresso in the same cup.

Milk Frother
Also called a steam wand, this pipe usually found on the side of the espresso machine is used to alter milk by raising its temperature and introducing tiny air bubbles, thus creating a thick, foamy froth to top a cappuccino or a latte.

Portafilter
A handle on one end and a cupped shape on the other, it holds the basket in place during the brewing process and allows easy manipulation for sealing the brewing chamber as well as littering used coffee grounds.

Power Source
Brewing espresso relies on two important factors: hot water and pressure. Energy must be converted to heat water and build that pressure, and the source of this energy is called the power source. It can be electrical or external, such as gas or wood, depending on the type of espresso maker.

Preset
This feature lets a person pre-determine, through a user-friendly interface, the quantity of coffee desired, such as a single or double shot of espresso, a cappuccino or a latte.

Pump
This device mechanically builds the pressure (8-10 bars) required to force hot water through coffee grounds, instead of depending on steam pressure which might result in brewing at a higher than ideal temperature.

Ristretto
Opposed to a long shot, a ristretto designates a short, one ounce shot of espresso.

Tamping (tamper)
This is the process through which coffee grounds are compressed within the basket prior to brewing. The tamper is the tool used for tamping, and typically requires 30 pounds of pressure for the perfect compaction.

Water Filter
In higher end espresso machines, a mechanical or a charcoal filter is integrated to remove unwanted components from tap water before the brewing takes place. If one uses natural spring water to prepare espresso, the natural minerals in it might actually contribute to the espresso’s flavor, eliminating the need for a filter.

Water Temperature
The ideal water temperature for brewing espresso is around 92.5 Celsius. If water is too hot, it will burn the coffee grounds; if it is too cold, it won’t be able to extract all the beans’ aroma, resulting in a weak taste.