Coffee & Espresso Glossary

The process of dissolving flavour compounds out of ground coffee using water — under- or over-extraction both throw the balance off.

The golden-brown foam on top of a fresh espresso shot, made of emulsified oils and CO₂ released during roasting.

Water finding an easy path through the coffee puck instead of flowing evenly, causing part of the shot to under-extract.

The part of the machine the portafilter locks into — where hot water is delivered into the coffee.

The handled fitting that holds the filter basket and coffee, locked into the group head to brew.

A temperature controller that holds boiler temperature far more precisely than a standard thermostat — key for consistent shots.

A single-boiler design that draws brew water through a tube inside the steam boiler — brews and steams together without a second boiler.

Two independent boilers — one for brewing, one for steam — allowing simultaneous brewing and steaming at their own ideal temperatures.

A gentle, low-pressure soak before full brew pressure kicks in — helps saturate the puck evenly and reduce channelling.

The grinding surfaces inside a grinder — flat or conical — that shear beans into consistent particle sizes rather than smashing them like blades.

Grinding only the exact amount needed per shot, rather than running a hopper — reduces stale bean carryover and lets you switch beans easily.

A grind adjustment collar with no fixed click points, letting you dial to an exact grind size anywhere across the range.

Ground coffee left behind inside a grinder's chute or chamber between doses — low-retention grinders are prized for single-dosing.

Stirring grounds with fine needles before tamping to break up clumps and distribute coffee evenly in the basket.

The amount of ground coffee used per shot — typically measured in grams for accuracy rather than volume.

Coffee sourced from one specific farm, region, or country, showcasing that origin's distinct flavour character.

Beans from multiple origins combined to create a deliberately consistent, balanced flavour profile — what most Australian cafés pour.

How long and hot beans are roasted — light roasts preserve origin character and acidity, dark roasts build body and reduce brightness.

The release of CO₂ from beans after roasting — freshly roasted beans need a few days' rest before brewing for the best results.

Coffee graded above a quality threshold by industry standards — traceable origin, careful processing, and distinct flavour.

Removing limescale buildup from a machine's internals using a descaling solution — the leading cause of machine failure is skipping this.

Running water (or detergent) backward through the group head to clean coffee oils from the internal valve — needed on most prosumer and commercial machines.

The mineral content of your water supply — hard water builds limescale faster and shortens machine life without filtration.

The compacted disc of spent coffee grounds left in the basket after a shot — its shape after extraction can reveal channelling issues.

The weight or thickness of a coffee on the palate — from light and tea-like to heavy and syrupy.

The bright, tangy quality in coffee (distinct from sourness when balanced) — often described as fruity or citrus-like in lighter roasts.

Finely textured steamed milk with tiny, glossy bubbles — the goal for flat whites, lattes, and latte art.

Not enough flavour pulled from the grounds — tastes sour, thin, or salty, usually from too coarse a grind or too short a shot time.

Too much pulled from the grounds — tastes bitter or harsh, usually from too fine a grind or too long a shot time.