Coffee Lexicon
Why a coffee lexicon?
A lexicon is important because it provides a standardized vocabulary for describing the characteristics, flavors, and preparation methods of coffee. This allows professionals in the coffee industry, such as baristas and coffee roasters, to communicate effectively with each other and with customers. It also helps coffee enthusiasts to better understand and appreciate the nuances of different types of coffee. Additionally, a coffee lexicon can be used as a training tool for those learning about coffee.
Dive in, and get your coffee geek mojo working!
BREWING BASICS
Bloom: Prewetting the coffee grounds to release excess gas and to aid the brewing process.
Brew ratio: The relationship between the weight of ground coffee and the volume of water used for brewing, typically reflected in grams.
Brew time: The length of time that water is in contact with ground coffee during brewing.
Dialing-in: The trade term for adjusting the grinder to produce coarser or finer grinds until it is in balance with the ratio of coffee to water and brew time.
Extraction: The amount of flavor removed from the coffee grounds during the brewing process.
Grind size: The size of ground coffee particles adjusted for proper extraction during brewing.
Over-extracted: When too much flavor has been removed from the coffee grounds, including the undesirable ones, resulting in a bitter and unpleasant-tasting coffee.
Turbulence: A mixing action created as water passes through and over the coffee grounds allowing for even and adequate extraction from the coffee grounds.
Under-extracted: When too little desirable flavor has been removed from the coffee grounds, resulting in a sour and weak-tasting coffee.
BREWING METHODS
AeroPress: A syringe-like device that makes a single cup of coffee using properties of both immersion and pressure brewing.
Chemex: An hour-glass shaped carafe that holds the filter in place and doubles as the coffee brewer and vessel, similar to a pour over but with increased grind size and brew time.
Cold Brew: A form of extracting coffee from ground coffee using cold or ambient water temperatures.
Drip coffee: A method of coffee brewing in which water passes through coffee grounds and a filter with the help of gravity.
French Press: A method of immersion brewing in which after the coffee grounds are steeped in water for a specific amount of time, a mesh filter is plunged through the coffee to separate the grounds from the beverage.
Immersion brewing: A category of brewing methods that involves steeping coffee grounds in water for a set amount of time.
Pressure brewing: A category of brewing methods that use pressure to force water through the coffee grounds to extract flavor.
Pour over: A manual method of making drip coffee using a cone-shaped dripper, a filter, and a kettle to pour water over the coffee grounds.
Tamping: Technique used in espresso brewing to pack down the ground coffee particles to for a flat tight bed.
ROASTING MACHINE & EQUIPMENT
Airflow: The route by which air moves through the drum to the chimney. Important to note for safety, maintenance, and flavor.
Air temperature: The temperature in the drum measured by a probe positioned on a roaster to enable the operator to read the ambient temperature. (Also referred to as exhaust temperature.)
Bean Probe: Any measuring probe positioned on a roaster to enable the operator to read external bean temperature.
Chaff Collector: The part of the roasting system designed to collect the chaff, the dried skin of the coffee bean that comes off during roasting.
Cooling Tray: A piece of equipment, usually circular and equipped with a sweep arm, which agitates fresh roasted coffee while ambient air is drawn through the screen to remove heat.
Drum Roaster: A cylindrical drum that rotates at a set speed to agitate coffee for roasting.
Fluid Bed Roaster: A drumless roaster which utilizes forced hot air to agitate and “float” beans for roasting.
Tryer/Sample Spoon: A small scoop mounted in the faceplate of a coffee roasting machine for removing a sample of beans during roasting.
Quenching: The process of cooling the roasted coffee either by airflow or water. Smaller scale machines manage this by pulling room temperature air through the hot beans in the cooling tray. Larger scale machines "water quench" the beans, or kick off the cooling process with a brief spray of water.
Ventilation: The movement of exhaust and cooling tray air which is moved from one point to another.
ROAST LEVELS OF COFFEE
Roast Color: Transformation of coffee color as it correlates to time and temperature during the roasting process.
Light Roast: A roast level produced by dropping beans before, or just after, the end of first crack.
Medium Roast: A roast level produced by dropping beans before, or just after, the onset of the second crack.
Dark Roast: A roast level produced by dropping beans after the second crack has finished.
THERMODYNAMICS
Exothermic: The release of heat and water pressure.
Endothermic: The absorption of heat by the green coffee.
Conduction: The transfer of heat from one substance to another by direct contact.
Convection: The transfer of heat through currents of liquid or gas. In coffee roasting, the transferring substance is air & the receiving substance is the coffee bean.
Forced Convection: Heat transferred through currents that are moved by an outside force such as a pump. In both drum and fluid bed roasters, forced convection is the major mode of heat transfer.
Radiant: Heat that is contained in the metal of the roaster. Think about your car getting hot when left in the sun. Acknowledge that it plays a part in the roasting process.
ROASTING CYCLE
Charge Temperature: Approximate temperature as recorded by the temperature probe of the roaster right before charging the coffee into the drum.
End Temperature: The temperature when the roast is stopped by discharging the roasted coffee into the cooling tray.
End Weight: The resulting weight of the roasted coffee. This is determined by subtracting the weight of the green coffee (x) by weight of the roasted coffee (y). Percentage difference is calculated by 𝑦−𝑥/𝑥 ∗ 100% = shrinkage
Rate of Rise: The progression of bean temperature per unit of time during the last cycle.
Roast Cycle: The roasting process by which the chemical and physical properties of green coffee beans are transformed into roasted coffee products.
Key changes include Drying Phase, Maillard Reaction, and Development (Caramelization and Pyrolysis).
Roast Curve: Roast curves generally follow an “S” curve due to a series of events: Charge Temp, Turn Around, First Crack Second Crack, Drop
Roast Profile Recording: The recording of a roast temperature path by means of temperature probes and time which generally results in the form of a graph.
Temperature Midway Point: The temperature calculated by the roaster for the midway point of the roast cycle.
GREEN COFFEE
Coffee Cherry: The fruit of the coffee tree. Each cherry produces either two coffee beans or one peaberry.
Coffee Chaff: Also known as “silver skin”, which is the innermost skin that may remain after processing in the coffee seed. It is often released during the roasting process
Commodity Coffee: Green coffee which fails to achieve a cup score of 80 points due to defects. Commodity coffee cup scores range from 65 - 79.9 points on the SCA Cupping form.
Moisture in Green Coffee: Water that is bound up inside the coffee seed. Water activity can help predict product stability and browning reactions. Generally accepted amounts range from 10.5% to 12%.
Speciality Coffee: Green coffee with a limited amount of allowable defects. Specialty Coffee Cup Scores range from 80-100 points on the SCA cupping form.
ROASTING PROCESS: CHEMICAL REACTIONS
Caramelization: A complex series of sugar-browning reactions that creates numerous new compounds.
Maillard Reaction: Chemical reactions involving amino acids and the reduction of sugars which contribute to roast flavors and coffee’s brown color.
ROASTING PROCESS: EVENTS
Charge Temperature & Weight: A set temperature determined by the roaster to load a specific weight of green coffee into the drum.
Turning Point: The moment at which an internal bean probe indicates the temperature rise of the green beans.
First Crack: An event in the roasting process whereby rupturing of the coffee bean cell wall occurs due to increasing steam pressure inside the cells producing an audible cracking sound.
Second Crack: An event in the roasting process where the beans become brittle due to dehydration and the release of CO2. As a result, the beans crack and begin to carbonize.
Drop: Discharging beans from a coffee roasting machine to a cooling tray.
ROASTING PHASES
Drying Phase: The period of time from the charge of the roast until a color change occurs in the green coffee. Usually determined by the change of the coffee bean color from pale green to pale yellow as moisture is being released during the roast cycle.
Cooling Phase: The phase in the roasting process when the batch is dropped into a cooling tray to stop the roasting process.
PHYSICAL CHANGES
Roast Volume Increase: The effect of coffee beans swelling due to the change in the microstructure from a dense to porous structure during the roasting process.