The first 20 coffee terms worth knowing

Recipe terms: dose, yield, ratio, bloom, agitation

A recipe is four numbers and one action. Dose is the dry coffee, weighed in grams. Yield is the liquid that reaches the cup, also weighed rather than judged by eye. Ratio divides yield by dose. Bloom is the first wetting. Agitation is anything that moves the bed: a stir, a swirl, a faster pour.

• Dose — dry coffee mass. A filter recipe commonly starts between 15 g and 20 g, and an espresso basket is often dosed in the same 15–20 g window.
• Yield — beverage mass. A modern espresso recipe stops at roughly twice the dose, so 18 g in produces about 36 g out, a ratio near 1:2.
• Brew ratio — dose against water. Published filter protocols sit between 1:15 and 1:18, and the SCA cupping ratio of 8.25 g per 150 mL works out close to 1:18.
• Bloom — the first pour, around twice the coffee mass in water, held for 30–45 seconds while the bed degasses.
• Agitation — stirring or swirling the slurry. It changes how quickly water moves through the bed, and therefore the time you are timing.

The wet bed keeps part of the water, which is why the scale in the cup reads low. In published V60-style measurements the spent coffee holds roughly twice its own mass in liquid, so a 300 g pour over a 20 g dose can finish nearer 260 g in the server.

Two habits make the rest of this list usable. Weigh dose and yield rather than measuring spoons and jugs, because volume varies enough between spoons to hide real changes. Then change one number at a time, so that a difference in the cup has one candidate cause.

Extraction terms: extraction yield, TDS, refractometer, evenness

The reference band used with the brewing control chart puts extraction yield at 18–22%, and it is the figure that separates "under-developed" from "over-developed" rather than simply "weak" from "strong".

• Extraction yield — dissolved mass divided by dose mass, expressed as a percentage.
• TDS — total dissolved solids, the concentration in the beverage; the same reference band places it at 1.15–1.45% for a brew sitting in the 18–22% range.
• Refractometer — the instrument that reads TDS as a percentage from a cooled, filtered sample, turning a taste into a number.
• Evenness — how uniformly water reached the bed. Two brews can land on the same extraction yield and still differ, because one worked the whole bed while the other worked the outside of the puck hard and the centre lightly.

The arithmetic connecting them is short. A 250 g beverage at 1.30% TDS holds about 3.25 g of dissolved coffee; from an 18 g dose that is an extraction yield near 18%. Keep the same cup and the same reading but raise the dose to 20 g, and the yield falls to roughly 16% — the quickest demonstration of why dose and taste cannot be discussed separately.

Evenness is where tasting language earns its place. An uneven brew presents sour and bitter at once, because the under-extracted and over-extracted fractions are both in the cup. A flat, hollow cup points the other way, at a bed that was worked hard and thin.

Grind terms: particle size distribution, fines, burrs, retention

A grinder does not produce one size. It produces a distribution, and the vocabulary of grind is really vocabulary about that spread.

• Particle size distribution — the share of grounds sitting in each size band. Working descriptions in the coffee literature set the fine band at 300–600 µm, the medium band at 600–800 µm and anything above 800 µm as coarse.
• Fines — the fraction below roughly 100 µm. In espresso, that fraction is the number to read against shot time, more than the mean size of the rest of the dose.
• Burrs — the two grinding surfaces, conical or flat. Their diameter and cut shape set the distribution rather than any single setting.
• Retention — coffee left inside the chute between doses, quoted in grams. It is the reason the first grind after a setting change can behave differently from the second.

The bands above are working bands rather than a standard, and they are used as directions instead of gates: espresso is ground at the fine end, pour-over sits in the medium-fine part of the range, French press goes coarse. For comparison, keep one variable fixed while another moves, because shifting both makes the result unreadable.

Roast terms: roast degree, first crack, second crack, roast loss

Roast names are shorthand for a time-and-temperature path. The measurable events along that path are the cracks and the weight change.

• Roast degree — where the roast stopped. Labels such as light, medium and dark describe that point in words; an instrument colour value replaces the word with a numbered reading taken from the same sample.
• First crack — the audible point at which bean temperature reaches roughly 196–205 °C and moisture escapes as steam.
• Second crack — the second audible event, near 224–230 °C, where the bean structure begins to fracture and surface oils appear.
• Roast loss — the drop in mass from green to roasted, commonly 13–20% across the range from light to dark.

Roasters also time the phase after first crack, because that is where most of the flavour-relevant chemistry sits. Development time is usually expressed as a ratio: 20–25% of the total roast spent after first crack.

The word on the bag is the weakest of these signals. Two roasters can print "medium" for roasts that differ by a visible margin in colour, which is why a colour reading, or a statement of where the roast stopped relative to the two cracks, travels better between bags than the adjective does.

Processing terms: washed, natural, honey

Processing decides how the fruit is separated from the seed, and all three routes end at the same green-bean target: a moisture content of about 10–12%, measured as the mass lost when a sample is dried at 105 °C.

• Washed — fruit is removed before drying; fermentation typically runs 12–36 hours, after which the seed dries on beds or patios for roughly 8–20 days.
• Natural — the seed dries inside the whole fruit, with cherries spread in thin layers and turned regularly until the target moisture is reached.
• Honey — part of the mucilage stays on the seed through drying, and the retained layer is what the colour names (yellow, red, black) describe.

These three words describe method. They do not carry a fixed flavour result, and they do not replace the origin, variety and roast information printed beside them on the same bag.