Coffee Glossary

Coffea arabica, the coffee species behind most specialty coffee. It generally grows best at higher altitudes, is more susceptible to disease than robusta and tends to produce sweeter, more acidic and more aromatic cups.

The bubbling that happens when hot water first meets freshly roasted ground coffee, as trapped carbon dioxide escapes. Many pour-over recipes start with a short bloom pour before the main brew.

The relationship between the weight of coffee and the weight of water (or, for espresso, the weight of the drink), written as 1:N. Filter coffee is often brewed around 1:15 to 1:17; espresso is often around 1:2.

The reddish-brown foam on top of an espresso, made of oils, gases and fine particles emulsified under pressure. It is a sign of freshness and pressure, but not on its own a guarantee of good flavour.

A standardised tasting method used by buyers and roasters to evaluate coffee. Ground coffee is steeped in hot water in bowls, the crust is broken and the coffee is slurped from a spoon so aroma and flavour can be compared.

In roasting, the time between the start of first crack and the end of the roast. Roasters adjust it to balance acidity, sweetness and roast flavours.

In espresso, the dose is the weight of ground coffee in the basket and the yield is the weight of liquid espresso in the cup. Together with the shot time they describe an espresso recipe.

The process of dissolving flavour compounds from ground coffee into water. Under-extracted coffee can taste sour and thin; over-extracted coffee can taste bitter and dry. Grind size, time, temperature and ratio all affect it.

An audible popping during roasting, when moisture and gases inside the beans expand and the bean structure cracks. Light roasts are often finished shortly after first crack begins.

Coffee seeds after processing and drying but before roasting. Green coffee is what is traded internationally; it is stable enough to be shipped and stored for months.

A method between washed and natural: the skin is removed but some or all of the sticky mucilage is left on the seed while it dries. Names such as yellow, red or black honey usually describe how much mucilage remains.

Also called dry process: whole coffee cherries are dried with the fruit still on the seed, and the dried fruit is removed afterwards. Naturals often taste fruity and heavy-bodied, and need careful drying to avoid defects.

Coffea canephora, the second major coffee species. It is hardier and higher-yielding than arabica, usually contains more caffeine and is widely used in blends, instant coffee and espresso for body and crema.

Coffee from one identifiable place - a country, a region or, more precisely, one farm or cooperative - rather than a blend of several origins.

How far a coffee can be tracked back through the supply chain, from the cup to the exporter, the washing station or the individual farm. Better traceability makes claims about quality and sourcing easier to check.

A processing method in which the fruit is removed from the coffee seeds before drying, usually followed by fermentation in water to loosen the remaining sticky mucilage. Washed coffees are often described as clean and bright.