Harvesting & Processing Methods

Green Coffee Glossary

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A

Anaerobic Fermentation

A type of coffee processing that usually refers to a sealed tank fermentation for depulped parchment. After depulping, the coffee is fermented either in clean water or the water used to depulp it, in an airtight tank to prevent new oxygen introduction, with a one-way valve for off-gassing. Technically speaking, all fermentation is by nature anaerobic. In coffee, fermentation occurs alongside aerobic maceration, thus the term anaerobic fermentation is usually applied to the sealed-tank style of processing which can limit the microbial population and activity.

B

Brix Scale

A method of measuring the sugar content of a solution, often employed in winemaking. Can be (sometimes controversially) used in coffee to determine cherry ripeness or degree of fermentation. Usually measured with a specific refractometer.

C

Carbonic Maceration

Similar to anaerobic fermentation, this is processing method involving a sealed tank fermentation step. However, carbonic maceration usually refers to whole cherry fermentation, instead of depulped parchment. Coffee cherries are often added to a large tank filled with clean water. The tank is sealed with a one-way valve for off-gassing of released carbon dioxide, and the environment allows no new oxygen in. The fermented coffee must be depupled after this step before drying.

Cherry Flotation

The pre-processing step responsible for cleaning the whole cherry before depulping, fermenting, and/or drying. Also functions to separate floaters – lower quality, low density fruits – from the sinkers, which are of higher density and quality. Sometimes referred to as “Triple Washed” or “Burundi Process.”

D

Demucilage

Partial or complete removal of the coffee’s mucilage down to the parchment. Fermentation is used to demucilage coffee. Alternatively, coffee’s mucilage may be removed with specialized equipment capable of removing more of the coffee fruit compared to a traditional depulper.

Demucilaginator

Machinery that can depulp and demucilage coffee cherries, allowing producers to dry the coffees, bypassing the fermentation stage of wet processing (though there is likely still some fermentation in the early drying stages). This technique uses lower amounts of water and less manual labor.

Depulping

The removal of fruit layers from the parchment coffee. There are a wide variety of machines able to depulp coffee, from manual to mechanical and eco-friendly.

Dry Mill

The location responsible for hulling parchment, sorting for defects, density, and screen size, and bagging for export

E

Eco-Pulper

A depulping machine, which can process large volumes of coffee cherries using less than a tenth of the water than is consumed in standard washing practices.

F

Fermentation

A metabolic process that produces chemical changes in organic substances through the actions of enzymes. In coffee, it refers to leaving the harvested beans (whether washed or in cherry) to rest and allow microorganisms, usually yeast and bacteria, to macerate the coffee fruit, which has a significant impact on final flavor profile. In washed coffees, this fermentation is used to demucilage parchment before drying.

H

Hand Picking

The traditional practice of harvesting coffee cherries using manual labor. Attentive workers may pick only ripe cherries, which can improve the sensory quality of the final product (though this is time consuming and labor intensive compared to mechanical picking). Pickers may also strip pick the cherries, pulling them all (ripe and unripe) at once from the branch.

Honey Process

A coffee processing method in which coffee cherry skins are removed and then dried without removing the mucilage. Also called “pulped-natural” or “semi-washed.”

Hulling

Removing the parchment and/or dried cherry skin from the seed prior to sorting and export. Takes place at the Dry Mill.

I

In-Cherry Fermentation

Fermentation of the whole fruit. While de facto in-cherry fermentation occurs during the natural process, it can also be employed in controlled environments, such as a sealed tank or covered raised bed.

M

Mechanical Harvesting

The act of picking coffee cherries using a machine. Mechanical harvesters function by straddling the trees, driving over them and oscillating at high speeds, causing coffee cherries to fall onto collection plates or the ground. Can only be accomplished on relatively flat terrain, most commonly in Brazil’s macro farming regions of Mogiana and Minas Gerais.

N

Natural

Also called “dry-process” or “fruit- or cherry-dried.” A coffee processing method of letting the coffee fruits dry with the skin and mucilage intact, which are removed later at a dry mill. Tends to produce the fruitiest tasting coffees.

P

Post-Fermentation Soak

A secondary tank used to hold coffee parchment in clean water immediately after depulping, fermenting, and washing. Fermentation continues but at a much slower pace due to the reduced microbial load in the slurry. Sometimes called “double washed” or “Kenya process.”

Post-Harvest Processing

All the aspects of coffee preparation that occur after harvest. Post-harvest processing covers everything at the wet mill and dry mill, from depulping, fermentation, drying, hulling, sorting, and bagging for export

W

Washed Coffee

A processing method in which the fruit is depulped with water and the remaining mucilage is removed using fermentation. The most widely used processing method in specialty coffee, but it uses a significant amount of water. Also known as “wet process” and “parchment-dried”.

Wet Hulled

A processing method that removes the parchment before the coffee cherry or parchment is completely dry. This technique is especially popular in Indonesia, where coffee is harvested and left to dry in cherry to 30-40% moisture. It’s then hulled to remove parchment, leaving the green bean exposed and to dried the rest of the way (usually down to 10-12% moisture). This is in contrast to most processing methods, where the parchment is left on the bean until just before shipping. Also known as giling basah, “seed dried,” and sometimes “semi-washed.”

Wet Mill

The location primarily responsible for washed coffee processing, fermentation, and drying both parchment and whole cherry. Also known as a beneficio, a factory, a washing station, a pulping unit, and many other names.