Reference

Glossary

Every term the guide uses, in one place. Roasting has a lot of jargon — but almost all of it names something simple.

Agtron number: A measurement of roast color on a standardized scale; higher numbers are lighter. The common shorthand for "how dark."
Airflow: How much air is moving through the roaster. On an air roaster it delivers most of the heat and tumbles the beans; on a drum it mainly controls convection and clears smoke and chaff.
Baking (baked): A defect from too little heat over too long a time — often a stalled or crashed Rate of Rise. The result tastes flat, bready and hollow. Color can look fine; the flavor isn't.
Caramelization: The thermal breakdown of sugars (from ~170°C) into caramel and toffee notes and browning. It builds sweetness — but consumes the sugar, so too much burns it away.
Chaff: The papery skin (silverskin) that flakes off beans during roasting. It's flammable and needs clearing — your Nano collects it.
Charge: Loading the green beans into the roaster, and the temperature at that moment (the "charge temperature").
Chlorogenic acids (CGAs): A large family of acids in green coffee. Heat breaks them into quinic and caffeic acids, which read as bitterness and astringency — rising as the roast goes darker.
Conduction: Heat transfer by direct contact, e.g. a bean against a hot drum wall. Powerful but can scorch.
Convection: Heat carried by moving hot air or gas. Even and easy to modulate — the dominant mode in your fluid-bed Nano.
Crash: A sudden drop in Rate of Rise, often near first crack, sometimes going negative. A classic cause of baked, flat flavor.
Development (phase): The stretch from the start of first crack to the drop, where roast character and final flavor are dialed in.
Development Time Ratio (DTR): The share of total roast time spent after first crack, as a percentage. Commonly targeted around 20–25%. See Chapter 7.
Drop: Ending the roast — releasing the beans to cool. The single most important decision you make.
Endothermic / exothermic: A roast mostly absorbs heat (endothermic), but around first crack the bean briefly releases heat (exothermic) as it pyrolyzes — which can destabilize the Rate of Rise.
First crack: An audible popping (~196°C true; ~212–226°C on a Nano) as steam and CO₂ split the bean open. It marks the start of development and drinkable roast levels. See Chapter 5.
Flick (flip): A rebound in Rate of Rise after a crash. The crash-then-flick combo in development is a much-chased fault, blamed for muddy flavor.
Fluid bed: A roaster design where rising hot air suspends and tumbles the beans — "fluidizing" them. Your Nano is a fluid-bed roaster.
Green coffee: Raw, unroasted coffee seeds. Dense, grassy and ~10–12% water, with almost none of coffee's aroma yet.
Look-ahead: The Nano controller's habit of anticipating the upcoming profile curve rather than only reacting to the current temperature, for smoother control.
Maillard reaction: Browning reactions between amino acids and reducing sugars (~140–170°C) that build most of coffee's color, body and nutty/malty/chocolate aromas. See Chapter 8.
Melanoidins: Large brown molecules produced by the Maillard reaction; they give roasted coffee its color and much of its body.
Milestone: A marked event in a roast — color change, first crack, second crack — used to compare roasts across time and machines.
Phase: One of the three stretches of a roast: drying, Maillard/browning, and development. See Chapter 4.
PID: The control algorithm (Proportional–Integral–Derivative) the Nano uses to hold the bean temperature to your profile.
Profile: A planned roast: a target temperature curve over time, plus airspeed and parameters. On the Nano you design it; the machine executes it.
Pyrolysis: Thermal decomposition of the bean (accelerating past ~200°C). It creates roast depth, CO₂ and oils — and, taken too far, smoke and ash.
Radiation: Heat as infrared energy beamed from a glowing-hot surface, without contact. A minor but real contributor in drum roasters.
Rate of Rise (RoR): How fast bean temperature is climbing, in degrees per minute — the slope of the temperature curve. It should decline smoothly. See Chapter 6.
Roast level: How far the roast was taken — light to dark — as a set of flavor trade-offs. See Chapter 9.
Scorching: Localized burning where a bean contacts a too-hot surface; a conduction fault more common on drums than on air roasters.
Second crack: A second, sharper crackle (~224°C true) as the bean's structure fractures further and oils emerge. The threshold of dark roasts.
Strecker degradation: A set of side reactions within the Maillard cascade that generate many of coffee's aroma compounds.
Temperature envelope: A Kaffelogic Studio feature for comparing or translating profiles between roasters by anchoring them to milestone temperatures.
Thermal mass: How much heat a roaster (and batch) stores. High thermal mass means momentum and forgiveness but slow reactions; your Nano runs low.
Tipping: Small burnt spots at the tips of beans, caused by too-aggressive heat early — another conduction-related fault.
Turnaround point: Early in the roast, the moment the cool beans stop pulling the reading down and the temperature begins to climb again.
Weight loss: The mass a batch sheds while roasting (~12% light to ~20% dark) — the most honest physical measure of roast level.
Yellowing (color change): The point (~150°C) where the bean turns from green to yellow and smells of toast — the end of drying and the start of browning.