Espresso Glossary

A quick reference for the terms used throughout our guides. See dialing in, machine types, and grinder burrs for deeper reading.

Dose - The mass of dry ground coffee put into the basket, measured in grams. A common single-basket dose is 18g.

Yield - The mass of liquid espresso in the cup. Often around twice the dose for a standard shot.

Brew Ratio - Dose to yield, written like 1:2 (18g in, 36g out). It is the main lever for shot strength; see dialing in.

Extraction - How much soluble material the water pulls from the grounds. Under-extraction tastes sour and thin; over-extraction tastes bitter and harsh.

Channeling - Water finding a low-resistance path through the puck, causing uneven extraction. Good puck prep prevents it; see puck prep.

Crema - The reddish-brown foam on top of a shot, formed by emulsified oils and dissolved CO2.

Portafilter - The handled holder that carries the basket and locks into the group head. All BrewCraft machines use 58mm.

Basket - The perforated metal cup holding the puck. Non-pressurized baskets rely on your grind and prep; pressurized baskets add a valve to force crema and forgive coarse grinds.

PID - A temperature controller that holds brew water to a tight, stable setpoint.

Heat Exchanger - A boiler design that draws brew water through a tube passing through the steam boiler, allowing brewing and steaming at once. See machine types.

Dual Boiler - Separate boilers for brew and steam, each temperature-controlled independently.

Single Boiler - One boiler that switches between brew and steam temperatures, so you wait between tasks.

Pre-infusion - A gentle wetting of the puck at low pressure before full pressure, promoting even saturation.

Burr - The grinding element. Flat burrs use parallel discs; conical burrs use a cone in a ring. See grinder burrs.

Stepless Adjustment - Grind setting with continuous, infinitely fine changes rather than fixed clicks.

Retention - Grounds left inside the grinder between uses; low retention favors single-dosing.

Single-dosing - Grinding one shot's worth of beans at a time instead of filling a hopper.

WDT - Weiss Distribution Technique: stirring the grounds with fine needles to break clumps before tamping.

Tamping - Compressing the dose into a level, firm puck.

Microfoam - Finely textured steamed milk with tiny, glossy bubbles, used for latte art. See milk steaming.

Backflushing - Cleaning the group by forcing water back through a blind basket, only on three-way-valve machines. See backflushing.

Descaling - Removing mineral scale from internal waterways. See maintenance & descaling.

TDS - Total dissolved solids in water, a measure of mineral content that affects taste and scaling. See water quality.

Cooling Flush - Running water through a heat exchanger group before brewing to drop overheated water to brew temperature.