Glossary: CT's Coffee Primer: A to Z

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Dry-Processed Coffee

One of the three main processing methods (along with wet processing and honey processing), this is the simplest and most organic method of processing where coffee is laid on raised drying beds that allow air to circulate around the fruit; no layers of the coffee bean are removed, resulting in a more fruity-tasting coffee. Also known as natural processing.

Fair Trade Coffee

Honey-Processed Coffee

One of the three main coffee processing methods (including dry- and wet-processing). Process in which skin and pulp are removed but some or all of the mucilage (or "honey") remains; this process is midway between dry- and wet-processing and can have one of three color attributes: yellow, red, or black (see photo), based on the amount of sun exposure during drying. Honey-processed coffees tend to be more complex than their washed counterparts, but not as fruity as natural, dry-processed coffees.

Hulling

Process for removing the coffee husk (outer layer of coffee bean); the two basic types of coffee hulling consists of wet and dry hulling. Each process is the same, but also can be very different. New methods of hulling are always being developed. Coffee hulling is a very important part of the coffee making process.

Milling

The process of preparing coffee beans, including hulling, polishing, grading and sorting, and removing defective beans.

 

Origin

The specific place where coffee is grown.

 

Polishing

Optional process in which any silverskin that remains on coffee beans after hulling is removed in a polishing machine. This is done to improve the appearance of green coffee beans and eliminate a byproduct of roasting called chaff. It is described by some to be detrimental to the taste.

Wet-Processed Coffee

One of three main coffee processing methods (including dry- and honey-processed). Another term for washed coffee; requires the use of specific equipment and substantial quantities of water; coffee cherries are sorted by immersion in water. Even though it involves more steps and in some ways, more resources, wet-processing is perhaps more "transparent" to the final coffee flavor, allowing other differences in the coffee (variety, farm environment and altitude) to be discernible in the cup.

COFFEE ATTRIBUTES

Acidity

The bright and dry taste that adds life to a coffee; one of the major categories used in professional coffee tasting. Along with flavor, body and aroma, acidity is helpful in determining the quality of a cup of coffee. When not used as a tasting standard, acidity can refer to the chemical pH present in coffee.

Aroma

This fragrance produced by hot, freshly brewed coffee is one of four main categories for tasting coffee. Along with flavor, body and acidity, aroma helps determine the quality of a cup of coffee.

Balanced

This tasting term applies to coffees for which no single characteristic overwhelms the others; it doesn't localize at any one point on the palate; is not imbalanced in the direction of one (often undesirable) taste characteristic.

Blend

A mixture of two or more single origin coffees. The idea behind blends is to take the best qualities from different origins to create a smooth, well-balanced tasting coffee.

Body

This term refers to the mouthfeel (or heaviness), richness and texture associated with tasting coffee. Body is one of four main categories used to evaluate coffee quality.

Clean

Tasting term describing a coffee free of flavor defects. A very subjective term evoking brighter acidity and less mouthfeel.

Complexity

Refers to the sensation of tastes shifting in the sampling process, giving depth to the coffee; the more divergent, subtle or distinct, flavors you can discern from a single coffee, the higher the complexity rating.

Finish

A term relatively recently brought over into coffee tasting from wine connoisseurship. It describes the immediate sensation after the coffee is spit out or swallowed. Some coffees develop in the finish, in that their taste changes in pleasurable ways right at the very end.

Fragrance

The scent of freshly ground coffee before it is brewed; once hot water is added for brewing, the smell of coffee is referred to as "aroma."

Grind

The particle size of ground coffee. The recommended grind depends on the brewing method. The grind should be adjusted to create the desired amount of coffee extraction. The finer the grind, the quicker coffee can be extracted.

Richness

Refers to body, partly to flavor, and at times even to acidity. The term describes an interesting, satisfying fullness. Range.

COFFEE CLASSIFICATION AND GRADING

Coffea Canephora

Also known as Robusta, producing 30% of the world's coffee. The Canephora crop is a lower growing, higher-bearing tree. It produces an inferior cup compared to Coffea Arabica and is often used in instant coffees or to add flavor enhancement to Italian-style espresso blends.

Grade

Grade is generally used to indicate coffee bean size, which is associated with coffee quality. While there are many exceptions, coffee beans grown at higher elevations tend to be denser, larger, and have better flavor. The process of determining coffee bean size, or grading, is done by passing unroasted beans through perforated containers, or sieves.

Hard Bean

A relative term describing coffee density, applicable to coffee grown at more than 4,000-4,500 feet; however, the density scale used can vary from country to country. Often designated as Strictly Hard Bean (SHB), and used interchangeably with Strictly High Grown (SHG).

Single Origin

Coffee that has not been blended, hailing from a single country, region or crop. Sometimes called straight coffee. Many coffee connoisseurs insist that single origin coffee is better because it is coffee at its purest form.

Soft Bean

Term used to describe coffee grown at low altitudes, usually considered inferior to hard beans grown at higher altitudes.

Supremo

Highest grade (and largest bean) of Columbian coffee.

Under-Developed Coffee

Term for a roast with green/stemmy/grassy/savory flavors, meaning part of the coffee bean is too light and it comes across in the taste. The whole bean doesn't have to be too light for it to be called under-developed.

Whole Bean

Unground roasted coffee beans. Whole bean coffee has the advantage of staying fresh much longer than ground coffee. Also, whole beans can be ground to different sizes for different machines and for optimum flavor.  

COFFEE BEAN ANATOMY

Caracol (Peaberry)

Spanish for "snail," also known as a "peaberry," this natural mutation results in only one coffee bean instead of the usual two inside its cherry. Only about 5% of most coffee harvests are caracols and have to be hand-sorted. There is much controversy about whether caracol, or peaberry, coffee tastes better. Proponents claim that it is less acidic and the flavor is stronger.

Cherry

The fruit of the coffee tree, the cherry is bright red when ripe and contains two coffee beans, or one peaberry (caracol).

Husk

Outer layer of the coffee bean that breaks away and gets discarded during the roasting process.

Mucilage

The sticky, sugary flesh, or inner pulp, of the coffee fruit that surrounds the two coffee seeds; also known as "mesocarp" or "honey." (Mucilage is found in most fruit; it is not unique to coffee.)

Parchment

Term for the layer of cellulose that protects each of the coffee seeds. When dried, this layer looks and feels like parchment paper, hence the name. Also known as husks.

Quakers

Unripened beans that are hard to identify during hand sorting and green bean inspection. They're often, but not always, caused by poor soil conditions which limit sugar and starch development. Technically this isn't a roast defect, but often it is only discovered after roasting.

Silverskin

The very thin-layered coating of the coffee seed with a somewhat silverish sheen. This layer comes off during roasting. Also known as "chaff."

ROASTING PROCESS

Baked

When coffee is heated for too long without reaching first crack; also known as "stalling" the roast. This invisible defect results in a distinctively hollow, flat flavor with little sweetness.

Bean Temperature

Roast degree is often defined by internal bean temperature, which cannot be measured directly, but can be approximated by the coffee bean surface temperature as measured by a bean probe (probe thermometer). Modern roasting systems monitor the surface temperature of roasting coffee beans, and can consistently recreate a roast by controlling the bean temperature vs. time profile. Final bean temperature, and time-temperature profiles, are now used in place of bean color monitoring for consistency in roasting. Internal bean temperatures are often cited along with bean probe temperatures when describing degree of roast, but actual internal bean temperature depends not only on the bean surface temperature, but also the time-temperature profile and type of roaster used.

Caramelization

Often confused with the Maillard reaction, caramelization also creates many flavor and aroma compounds. However, the chemical process is different. You’ll know it’s happening by the slightly more caramel notes wafting from your roaster. It begins soon after the Maillard reaction.

Charge Temperature

Temperature of the coffee roasting drum just before coffee beans are added.

Coffee Grinding

Coffee grinding is a crucial step in coffee processing and, when done properly, can dramatically improve coffee extraction and aroma retention, thereby optimizing the brewed coffee quality.

Cupping

Standardized sensory coffee evaluation system based on a specific protocol to determine a coffee's aroma, acidity, body, and flavor. It has the clear purpose to evaluate the quality of coffee beans and was originally introduced to allow green coffee buyers to assess the flavor profiles of coffees before buying.

Degassing

A natural process where freshly roasted beans release carbon dioxide gas rapidly. Most roasters give their fresh coffee up to 24 hours to degas before assessing quality.

Density

One of the basics of coffee roasting, higher-altitude grown coffee beans are usually denser. Coffee beans with a higher density are more desirable because sugar content and flavors are more developed, leading to better acidity. density also depends on the moisture content of the bean — meaning the freshness, processing quality, storage, and other factors. Higher density tells us there is a greater concentration of cells and a more compact cell structure than its lower density counterparts. How that bean absorbs energy, withstands pressure, cracks, and develops is going to vary from beans with lower density

Development

This can refer to both the amount of development that the compounds in coffee beans have undergone and the period during roasting when those compounds are developed.

Endothermic Phase

When coffee beans absorb energy in the form of heat during the roasting process.

Endpoint

The final temperature the roast will end at; determines roast degree.

Exothermic Phase

When coffee beans release energy from the heat of coffee roasting through a first and second crack.

Infrared Roasting

Considered by most as the superior method to roast coffee, which heats the coffee faster, more uniformly and at relatively lower temperature than conventional hot air/flame roasters.

Moisture Content

Water bound up inside the coffee seed. When a coffee cherry is picked, the seed is full of water and must be dried before being bagged up and sold. Moisture content matters because it is an indicator of coffee quality. Moisture content of no higher than 12% helps protect the coffee beans’ other compounds and limits their ability to escape and degrade, even from the shelf.

Rate of Rise (RoR)

The speed at which speed increases inside the roaster; also impacts coffee's acidity, body, flavor profile, and more.

Resting

The practice of allowing just-roasted beans to rest and de-gas for a few days before packaging the whole bean, or grinding, packaging, and shipping.

Roast Master

Individual in charge of coffee selection, blending, and roasting operations.

Roast Profiling

The process of recording temperatures, times, and other variables during roasting to document patterns, tests, and results.

Roasting Curve

The coffee roasting curve is an important tool that can be used to understand the coffee roasting process. A typical curve displays the roast time along the x axis (usually in minutes) and the roaster temperature on the y axis (in °C or °F). The curves may typically also display rate of rise on a secondary axis. Each curve is a graphical representation of what happened during the roast.

Sample Roasting

Process of roasting a small sample of green coffee to evaluate quality and select an ideal roast profile.

Scorching

Scorching happens when the “charge temperature”, which is the initial temperature, is overly high and the drum speed isn't fast enough. It's easy to recognize. Dark, burnt patches will appear on flat sections of the coffee bean surface; it's literally been scorched.

Stalling

See Baked.

Strecker Degradation

A complex reaction where amino acids react with carbonyl grouped molecules. The reaction is dependent on other compounds created during the Maillard reaction. Aldehydes (e.g. vanilla) and ketones are both formed during this reaction. It also contributes to the brown color of the coffee.

Tipping

Roasting error where the bean appears burned on one spot, indicating that the beans experienced too much heat around a specific area.

Water Activity (aW)

Water activity is a good determinant of the coffee bean’s structural integrity, which influences its ability to retain moisture and volatile aromatic compounds. Put another way, it helps determine the coffee beans’ stability and ability to retain moisture and other desirable attributes that are called out in its flavor profile and in cupping. Water activity also has the ability to predict the potential and rate of changes related to browning reactions like caramelization and Maillard reactions. /span>

Turning Point

The turning point is the first big change in the roasting profile. It's when the heat stops falling, and starts increasing instead.

Yellowing

Early in the roasting process when the coffee beans start to dry. Shortly afterward, they’ll begin browning.

ROASTING STAGES

Drying Cycle

The first, endothermic phase of roasting coffee where the temperature of the beans rises to around 210 degrees Fahrenheit. The beans go from green to a light yellow.

First Crack

The second, exothermic stage of roasting where the temperature of the beans rises to around 350 degrees Fahrenheit. The beans turn a light brown and make an audible “cracking” noise as the beans fissure and release vapor.

Pyrolysis

The third, endothermic phase is at the heart of roasting, where beans develop the flavors and aromas of coffee as sugars and fats continue to change.

Second Crack

The fourth, exothermic stage of roasting where the temperature of the beans rises near 430 degrees Fahrenheit. The beans turn a dark brown as a new wave of chemical reactions take place, producing the ashy bitterness of very dark roasts.

Cooling Stage

The final stage where the beans are dumped into a cooling tray where they are blasted with cool air and spun. The final moments of roasting happen here as the beans go from 400 degrees to room temperature in minutes.

COFFEE ROASTING EQUIPMENT

Afterburner

An afterburner is a pollution-control device that allows roasters to comply with environmental regulations without sacrificing the quality of their roasts. Also known as a thermal oxidizer.

Air Roaster

An air roaster, or fluid bed roaster, is a machine that uses fast streams of hot air to roast coffee beans. There are different types, or configurations, of air roasters, but all use hot air to convectively roast the beans and to help keep the beans moving. Most commercially available coffee is either air roasted or drum roasted.

Batch Roaster

Batch roasters produce a fixed quantity (lbs per batch) of roasted beans at a time. In a batch roaster, the beans are removed before roasting the next batch. Continuous roasters produce roasted coffee at a fixed rate (lbs per hour).

Bean Probe

A probe thermometer used to monitor bean temperature during the roasting process. Bean probes accurately measure the surface temperature of coffee beans during roasting. Modern roasting systems use either resistance thermal detector (RTD), or thermocouple (TC), bean probes, along with electronic temperature controllers, to monitor and control the roasting process.

Blade Grinder

A coffee grinder that uses spinning blades to turn whole bean coffee to ground coffee. A blade grinder is simple and effective, but will produce an inconsistent particle size, or grind, compared to a burr grinder. 

Burr Grinder

A burr grinder, or burr mill, uses rotating flat to conical metal disks with sharp ridges, or burrs, to evenly grind the coffee beans. A burr grinder is typically adjustable from very fine to coarse and produces a consistent particle size compared to the simpler blade grinder. Consistent particle size is important in brewing quality coffee, making burr grinders the choice of coffee professionals.  

Color Reader

A measurement tool that helps read and classify the roasting degree, or the delta, between whole bean and ground in order to get a better understanding of the roasting curve and roasting result, as well as the consistency.

Coffee Grinder

A coffee grinder grinds coffee beans to specific textures with maximum efficiency. A good grinder ensures the ground coffee doesn't clump together, keeps the beans cool while grinding and helps evenly distribute coffee in the basket. Uneven grinds, on the other hand, cause all sorts of problems. See Blade Grinder and Burr Grinder.

Continuous Roaster

Large commercial roasters that roast a large volume of coffee at a time; inappropriate for specialty coffee roasting due to cost, the large volume of coffee roasted, and the inability to easily stop and reload the roaster with a different type of coffee bean.

Density/Moisture Meter

A measurement tool that measures the density and moisture of coffee cherries, parchment, green beans and roasted beans. Allows for better consistency, quality control, and customer satisfaction.

Destoner

Destoner is a machine to run coffee beans through after roasting to find any potential foreign matter that may have shipped with the green coffee. Read our article to know if you need a destoner for your coffee roaster.

Disc Grinder

Industrial grinder suitable for grinding smaller coffee batches (500-1,000 lbs/hr); delivers optimal grind uniformity and minimizes heat buildup that can alter coffee’s volatiles. Good choice when considering cost and flexibility.  

Fluid Bed Roaster

See Air Roaster.

Mixer

Piece of equipment that is used to mix roasted coffee for flavoring, or simple blending.

Roast Graph

Reference software displayed on a screen attached to a coffee roaster providing data that, when interpreted correctly, can improve coffee roasts, troubleshoot issues, and consistently repeat results.

Roller Mill Grinder

Heavy-duty industrial grinder used mainly for large-capacity coffee grinding (600-16,000 lbs/hr). Great for producing a consistently ground coffee with extremely uniform particle size. 

Sample Roaster

A sample roaster is a small, tabletop roaster designed for very small batch sizes (around 30–300 g), depending on the machine.

Scales

Scales are used to weigh coffee before and after roasting. When a pound of coffee is roasted, it will lose 15-20% of its weight. This means a pound of unroasted coffee does not equal a pound of roasted coffee.

Sealer

Machine used to vacuum- seal coffee bags.

Thermal Oxidizer

A Direct Fired Thermal Oxidizer (DFTO), also known as an Afterburner, or Direct Flame Thermal Oxidizer, destroys Volatile Organic Compounds (VOCs) and Hazardous Air Pollutants (HAPs), that are created through chemical processes found in industrial exhaust streams.

COFFEE ROASTER COMPONENTS

Burner Room

Pilot flame and burner is inside this area as well as the flame.

Chaff Tray/Collector

Chaff, or silverskin, is the tiny layers of dried skin or husk on the beans. These will come off during roasting. A chaff tray/collector will catch chaff.

Cooling Tray/Pan

Unless your roaster comes with a built-in cooling cycle, you’ll want to cool your freshly roasted beans as quickly as possible. This will prevent them from continuing to develop/roast due to the hot environment. A cooling tray or pan is ideal for this. Most industrial coffee roasting cooling trays cool the coffee beans in three minutes.

Cyclone Separator

Used to separate particulates, such as chaff, from roaster exhaust. The exhaust from a cyclone separator is typically passed through a thermal oxidizer (incinerator) to burn the smoke. Roasters equipped with both a cyclone separator and thermal oxidizer emit a clean, smoke and particle free, exhaust.

Dust Drawer

This drawer is for cleaning the chaffs that drop down during the roasting from the drum gap.

Dust Room

This area collects the chaffs from exhaust air and does not let the chaff go off.

Dust Room Gate

This gate allows one to open and clean inside the dust room. There are two gates in the dust room. The above gate is not usable during the roasting. Do not open it during roasting. One can use the below gate for cleaning the dust room during roasting.

Exhaust Air Valve

Enables one to adjust the exhaust fan suction. 

Hopper Valve

By opening this valve, the green beans fall inside the drum.

Loading Hopper

Where green coffee beans are loaded into the coffee roaster.

Mixer Discharge Gate

Where the coffee beans are released.

Moisture Analyzer

Analyzes moisture and density of coffee beans.

Sampler Spoon

Enables to check the beans during the roasting.

Viewing Window

Enables one to see the roasting process inside the drum during roasting.

ROASTING PROFILE TERMS

Light Roast

Light roast coffee is a light brown color and has no oil on the surface of the beans. These coffees typically have a crisp acidity, a mellow body, and bright flavors. These coffees are roasted in order to preserve the unique characteristics of the bean. In roasting, a lightly roasted coffee won’t have been taken far beyond first crack. However, the beans also face the greatest risk of being underdeveloped and having grassy or sour notes.

Medium Roast

Medium roasted coffees are medium brown in color with more body than light roasts. Like the lighter roasts, they have no oil on the bean surfaces. However, medium roasts lack the grainy taste of the light roasts, exhibiting more balanced flavor, aroma, and acidity. While roasting, beans you want to be medium-roasted will be approaching or just reaching second crack.

Espresso, Filter, Omni

Some roasters will roast a coffee slightly darker if it’s going to be used as an espresso or slightly lighter if it will be used for pour over. Other roasters like to find a roast profile that they believe is suitable for both espresso and filter: something called an omni roast.

Cinnamon/Blonde Roast

More names for light roasts.

City, City+, Full City, Full City+

Generally speaking, a City roast is a light roast, a City + a medium-light roast, and a Full City or Full City + a medium roast.

Vienna/French/Italian

Generally speaking, a Vienna or Light French roast is a dark roast, a Full French roast even darker, and an Italian even darker still.

COFFEE PACKAGING

Doypack

Most often used for smaller coffee packs, making it best suited to retail. The pre-shaped bottom allows it to stay upright well. The doypack coffee bag is simple in design and easy to use, both for the coffee roaster and the consumer.

Flat Bottom

A block bottom and four-cornered seal structure make the bag stand up straight even when containing heavier coffee bean products. Degassing valves are attached to the interior side on the top to release carbon dioxide.

Laminated Barrier Film

Coffee bags are made from layers of this film designed to protect coffee (ground or whole bean) from moisture, vapor, odor, or any other negative elements.

Nitrogen Flushing

Method used to preserve and protect food from damage during shipping and storage. Nitrogen replaces the oxygen in a food storage bag, and it cushions the contents. NItrogen-flushed coffee is used for storage to help preserve coffee beans. Using nitrogen to flush the package removes oxygen from direct contact with the coffee beans. The sealed package protects the coffee beans from interior and exterior oxygen. Read our article about nitrogen flushing.

One-Way Valve/Vent

A valve built into a coffee bag that lets carbon dioxide out, because freshly roasted coffee needs to de-gas.

Pillow 

The most common type of flexible packaging option that forms the shape of a pillow. Once filled, it balloons from the middle and flattens out at the top and bottom seals.

Side Fold/Gusseted 

The side fold (or gusset) bag is the recognized format for coffee packaging today. It is the tried and true coffee bag, and offers the most selection. The name comes from the side folds or "gussets" on the bag.