Espresso Coffee Terms

Here are some common definitions of terms used and related to espresso coffee brewing:

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Blend

A mix of different coffee beans from various regions, designed to create a balanced flavour profile with consistency.

Bloom

The initial release of carbon dioxide when hot water first contacts the coffee grounds. This is typically seen in drip brewing but can also occur with espresso, particularly if the coffee is freshly ground.

Brew Ratio

The ratio of coffee grounds to water used in brewing. In espresso, this is typically around 1:2, meaning for every 1 gram of coffee, 2 grams of water is used.

Channelling

A flaw in the extraction process where water finds paths of least resistance, leading to uneven extraction and a less-than-ideal espresso shot.

Crema

The golden-brown, foamy layer of bubbles that forms on top of a well-pulled espresso shot. It is a sign of freshness and proper extraction.

Dosing

The process of measuring the amount of ground coffee used in the portafilter. Common doses are typically 18-20 grams for a double shot.

Double Shot

A shot made using two times the amount of coffee grounds, typically yielding around 2 ounces (60 millilitres) of espresso.

Espresso Blend

A blend of beans specifically crafted to produce a desirable espresso shot with balanced acidity, sweetness, and body.

Espresso Machine

A device used to brew espresso by forcing hot water through finely-ground coffee beans. It typically has a pump or lever to create pressure, a steam wand for frothing milk, and a portafilter.

Extraction

The process of drawing flavours and compounds from the coffee grounds into the water during brewing. Proper extraction produces a well-balanced espresso shot.

Flow Rate

The speed at which water passes through the coffee grounds during extraction, influencing the espresso’s strength and flavour.

Grind Size

The fineness or coarseness of the ground coffee beans. Espresso requires a very fine grind to create the necessary resistance for proper extraction.

Group Head

The part of the espresso machine where the portafilter is locked into place. Water is forced through the coffee grounds from the group head during brewing.

Microfoam

The fine, velvety foam created by steaming milk, ideal for latte art and a smooth texture in milk-based coffee drinks.

Over Extraction

Occurs when the espresso is brewed for too long or with too fine of a grind, leading to bitterness and undesirable flavours.

Portafilter

A metal filter basket with a handle that holds the ground coffee during brewing. It is locked into the group head of the espresso machine.

Pre-Infusion

A technique where a small amount of water is introduced to the coffee grounds before the full extraction begins, allowing the coffee to bloom and reducing channelling.

Pressure

Espresso brewing requires about 9 bars (about 130 psi) of pressure to force water through the coffee grounds. This high pressure is a hallmark of espresso machines.

Puck

The compressed, used coffee grounds left behind in the portafilter after brewing. A well-formed puck is flat and solid, indicating an even extraction.

SCA (Specialty Coffee Association)

An organization that sets standards for coffee quality, including those related to espresso brewing, grind size, and equipment.

Shot

A single serving of espresso. A standard shot is about 1 ounce (30 millilitres) of liquid.

Shot Time

The length of time it takes to brew an espresso shot, usually between 25-30 seconds. This time affects the flavour profile and overall quality of the shot.

Single Origin

Coffee beans sourced from a specific region, farm, or estate, offering unique flavour profiles compared to blends of beans from multiple regions.

Steam Wand

A metal wand attached to the espresso machine, used to froth milk for drinks like lattes and cappuccinos. The steam wand heats and aerates the milk, creating microfoam.

Tamping

The process of pressing the ground coffee into the portafilter basket with a tamper to ensure an even extraction. Proper tamping is crucial for a balanced shot of espresso.

Thermal Stability

The ability of an espresso machine to maintain a consistent temperature throughout the brewing process, which is essential for optimal extraction.

Under Extraction

Occurs when the brewing time is too short or the grind is too coarse, leading to sour, weak, or underdeveloped flavours.

WDT (Weiss Distribution Technique)

A technique used to evenly distribute the ground coffee in the portafilter before tamping to reduce clumping and improve extraction.

These terms cover many of the technical and practical aspects of espresso coffee brewing. Mastering these concepts can help improve both the process and the quality of your espresso.