Glossary
Every term in coffee, defined plainly, cross-linked, and free of the jargon it explains.
Coffee glossary
Every term you will meet, defined plainly.
- AcidityThe bright, tart quality of a coffee, carried mostly by malic, citric and phosphoric acids. A quality in specialty coffee, a fault only when it is sour.
- BodyThe weight and texture of a coffee in the mouth, from the dissolved solids and the oils and fines the filter let through.
- Brew ratioThe weight of dry coffee against the weight of liquid it produces, written 1:2 for espresso or 1:16 for filter.
- BurrThe cutting surface of a grinder, either a cone turning in a ring or two flat rings facing each other. Burrs cut coffee to a size; blades break it at random.
- CuppingThe standard protocol for tasting coffees side by side: same dose, same water, same grind, in open bowls with no filter.
- DegassingThe release of carbon dioxide from roasted coffee, fastest in the first days after roasting and still measurable weeks later.
- DoseThe weight of dry coffee going into a basket or a brewer, always in grams. The first number of any brew ratio.
- FinesThe smallest particles produced by grinding, well below the target size. They extract fastest and can block the flow through a bed.
- First crackThe audible cracking of coffee beans in the roaster as steam pressure splits their structure, around 196 °C. The start of drinkable roast.
- Grind sizeHow finely the coffee is cut, which sets how much surface the water meets and therefore how fast extraction happens.
- Honey processDrying the bean with some of its sticky mucilage still attached. Sits between washed and natural, sweet with moderate acidity.
- MicrofoamSteamed milk whose bubbles are too small to see, giving a glossy, paint-like texture that pours as one body with the espresso.
- Natural processDrying the coffee cherry whole around the bean, so the fruit ferments against it. Heavier, sweeter, with berry notes.
- Over extractionPulling too much out of the coffee, which brings bitterness, dryness and an ashy finish. The cure is a coarser grind or a shorter contact.
- PortafilterThe handled basket holder that locks into an espresso machine group. Bottomless versions remove the spouts so the underside of the puck is visible.
- PuckThe compacted bed of ground coffee in an espresso basket, and the thing that decides where the water goes.
- PurgeRunning a short burst of water or grinding a few grams to clear what is stale in a machine or a grinder before the real dose.
- Q graderA taster licensed by the Coffee Quality Institute to score green coffee on the hundred-point scale, after passing twenty-two calibrated exams.
- RefractometerAn instrument that reads how much dissolved coffee a brew contains, by measuring how the liquid bends light. It reports TDS.
- RetentionGround coffee left behind in a grinder after a dose, which comes out stale in the next one.
- TampingCompressing the ground coffee in a basket into a level bed, so the water meets an even resistance.
- Under extractionPulling too little out of the coffee, which leaves it sour, thin and salty. The cure is a finer grind, a longer contact or hotter water.
- VarietalThe botanical variety of the coffee plant, such as Bourbon, Caturra, SL28 or Gesha. It sets a ceiling on the cup, not the cup itself.
- Washed processRemoving the fruit from the coffee cherry before drying the bean, usually with fermentation and water. The cleanest, brightest of the three main processes.
- BloomThe initial wetting of a filter coffee bed, during which trapped carbon dioxide escapes. Usually 30 to 45 seconds.
- ChannellingWater finding a low-resistance path through an espresso puck, over-extracting that path and under-extracting everything else.
- CremaThe emulsion of carbon dioxide, oils and fine particles that sits on top of an espresso. A sign of freshness, not of quality.
- Dialling inAdjusting grind, dose and yield until a coffee tastes the way it should on a given machine.
- ExtractionThe process of dissolving soluble compounds out of ground coffee into water.
- RistrettoA restricted espresso, typically around a 1:1.5 ratio, with a shorter yield and a denser texture.
- TDSTotal dissolved solids: the concentration of coffee in the cup, measured with a refractometer and expressed as a percentage.
- WDTWeiss Distribution Technique: stirring the dose in the basket with fine needles to break clumps before tamping.