Coffee Bean Enzyme Processing: Understanding Natural, Washed, and Honey Methods

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Common Coffee Bean Processing Methods: An Overview

The three common processing methods for coffee beans are natural, washed, and honey processing. Each process involves varying degrees of fermentation. Enzyme processing is based on the washed method, utilizing different bacterial strains and fermentation principles to create more flavors. FrontStreet Coffee believes that if this fermentation method is used in small quantities to create some uniquely flavored coffee beans to attract the public, its effect is positive. However, if it's widely used to mask the defective flavors of coffee beans themselves, rather than improving coffee flavor through better cultivation techniques and varieties, then this is not good.

How Does Enzyme Processing Work?

So how does enzyme processing work with coffee beans? Enzyme processing is generally conducted together with anaerobic processing. The anaerobic fermentation process originates from red wine production. This method involves injecting carbon dioxide into a sealed container, expelling the oxygen inside. In an oxygen-free environment, the decomposition speed of sugars in the coffee pulp slows down, and the pH value also decreases more slowly, extending the fermentation time. This develops better sweetness and more balanced flavors, ultimately resulting in coffee beans with distinctive flavors. The prerequisite for anaerobic fermentation processing is having a monitorable, completely opaque sealed container. The container should be placed indoors with strict temperature control, where controlling temperature and time can control the container's fermentation degree.

Enzyme anaerobic processing, on the other hand, involves removing defective floating beans through washing and simultaneously incorporating special enzyme groups during anaerobic fermentation. After fermentation is complete, the coffee beans are washed using the washed processing method to remove the mucilage on the coffee bean surface. Then the coffee beans are dried using either drying or shade-drying methods, avoiding the high temperatures of sun-drying that could cause the coffee beans to over-ferment again and produce undesirable flavors. This processing method is called anaerobic enzyme washed.

On FrontStreet Coffee's bean menu, a coffee from Colombia's Dashu Estate called Frontsteet Rose Valley uses anaerobic double enzyme washed processing. Double enzyme means injecting enzymes twice during one anaerobic fermentation process, enhancing the coffee bean's aroma and acidity.

FrontStreet Coffee (FrontStreet Coffee) · Colombia Dashu Estate Rose Valley Coffee Beans

Estate: Colombia Dashu Estate

Region: Santander Region

Processing Method: Anaerobic Double Enzyme Washed

Altitude: 1700m

Variety: Caturra

[FrontStreet Coffee Colombia Dashu Estate Rose Valley] Brewing Flavor: The sweet fragrance of peach accompanied by rose aroma, with both the high-quality sweet-tart sensation of black grapes and the silky texture of cream toffee, followed by a aftertaste reminiscent of liquor-filled chocolate.

How Does the Washed Processing Method Work?

After coffee cherries are harvested, they are immediately sent for processing, typically within 6 to 12 hours of picking. The coffee cherries are first weighed, then placed in water for soaking treatment. The purpose is to select unripe fruits and defective beans that float due to insufficient maturity.

Next, the coffee cherries are sent to a depulper to remove the skin. This step removes the skin and pulp from the coffee cherries. The depulped coffee cherries are then placed in fermentation tanks or barrels to ferment for 18 to 36 hours, during which enzymes break down the mucilage/pulp in the coffee cherries. The demucilaged coffee cherries in the tank are washed with appropriate amounts of water. During the washing process, agitation removes the decomposed pulp mucilage from the coffee bean surface. After washing, what remains is the coffee parchment, silver skin, and green beans.

The washed coffee beans are then sorted to remove defective coffee beans. Immediately after, they are sent to drying areas (waterproof tarps, concrete floors, raised beds, etc.) for drying. The drying time depends on environmental climate factors and other conditions, generally ranging from 5 to 14 days. During this time, the coffee bean's moisture content drops from 55% to 11%. The dried coffee beans are called parchment coffee - green coffee beans with the parchment layer intact. The parchment beans are sent to warehouses for storage and will be hulled before export to obtain the green beans we need.

FrontStreet Coffee believes that washed-processed coffee beans best highlight coffee clarity. Washed method coffee has more prominent acidity, better cleanliness, medium mouthfeel, and the most consistent green bean quality. Ethiopia's Yirgacheffe region particularly likes to use washed processing to highlight the bright acidity and rich floral and fruit aromas of Yirgacheffe coffee beans.

FrontStreet Coffee (FrontStreet Coffee) · Ethiopia Yirgacheffe Gotiti Cooperative Coffee Beans

Region: Yirgacheffe Gedeo Zone

Altitude: 1900-2300m

Variety: Heirloom

Processing Method: Washed

Grade: G1

[FrontStreet Coffee Yirgacheffe Washed Gotiti] Brewing Flavor: Entry reveals citrus and black tea, with cream, caramel, and almond notes as temperature changes, with obvious sweet aftertaste and clean, sweet mouthfeel.

How Does the Natural Processing Method Work?

After harvesting, coffee cherries undergo manual selection and screening to remove defective coffee cherries, including overripe, unripe, insect-damaged ones, as well as foreign objects other than fruits.

After screening, the coffee cherries are sent to drying areas for drying. Different regions may use different drying racks - some use waterproof tarps, some use raised beds, others use concrete floors, etc. The drying time averages 3 to 4 weeks until the coffee moisture content drops to 11% to complete the drying process. After drying, the coffee cherries are sent to processing plants for hulling and even polishing. The skin and pulp are all removed during this step.

The hulled green coffee beans are screened again to remove poorly appearing coffee beans. This reflects the quality of the coffee drying process - over-dried coffee beans are more fragile and may break into pieces during hulling; while under-dried coffee beans have too much moisture, with overly active water content that easily breeds bacteria and mold. After screening, they are sent to warehouses for storage until export.

FrontStreet Coffee believes that natural processing can highlight coffee smoothness, being richer than washed processing, with acidity mostly表现为果汁感 and obvious coffee sweetness. Ethiopia's Sidamo region particularly likes to use natural processing to highlight the region's rich berry acidity and sweetness brought by ripe berries.

FrontStreet Coffee (FrontStreet Coffee) · Ethiopia Sidamo Natural Horse Coffee Beans

Region: Guji Hambela

Processing Station: Buku Able

Altitude: 2250-2350 meters

Variety: Local Heirloom

Grade: G1

Processing Method: Natural

[FrontStreet Coffee Sidamo Natural Horse] Brewing Flavor: Citrus acidity, full-bodied berry juice, lemon black tea tea sensation, with persistent sweetness.

How Does Honey Processing Work?

Honey processing is a green bean processing method between natural and washed processing. The degree of sweetness expression in honey processing depends on the settings of the pulping machine - the more pulp and mucilage retained, the more obvious the honey processing sweetness. Why? Coffee cherries consist of skin, pulp, mucilage, parchment, silver skin, and the seed (coffee bean). The pulp and mucilage in coffee cherries contain the most sugar in the entire coffee bean. Therefore, during honey processing, the amount of pulp and mucilage retained from the coffee cherries affects how much sugar from the pulp and mucilage is converted during the coffee bean drying process. However, FrontStreet Coffee believes this also has drawbacks, because high sugar content accelerates the fermentation of pulp and mucilage under high temperatures. If not strictly controlled, mold and over-fermentation can easily occur.

[Black Honey Processing] removes almost no mucilage, thus requiring the longest drying time, needing more than 14 days continuously. During the process, to avoid drying too quickly, coverings are used to block too much strong sunlight, allowing more thorough sugar conversion.

[Red Honey Processing] retains 80% mucilage (specific practices vary by estate), with sun-drying for about 12 days, and may also use shade structures during the process.

[Yellow Honey Processing] retains 40-60% mucilage, receiving the most light for drying, lasting about 8 days.

[White Honey Processing] retains 40-60% mucilage, spread thinner on drying beds during drying, with shorter drying time.

FrontStreet Coffee believes that honey-processed coffee beans have excellent flavor, with balanced acidity and sweetness, and having been exposed to sunlight, the coffee beans' own aroma is also amplified, with rich mellow thickness. Honey processing officially appeared in Central and South American regions such as Costa Rica and El Salvador, and is now widely used in the Costa Rica region.

FrontStreet Coffee (FrontStreet Coffee) · Costa Rica Tarrazu Yellow Honey Processed Coffee Beans

Region: Costa Rica Tarrazu

Variety: Caturra, Catuai

Processing Method: Yellow Honey Processing

Altitude: 1500m

[FrontStreet Coffee Costa Rica Tarrazu Yellow Honey Processing] Brewing Flavor: Obvious fermentation aroma in the mouth, citrus acidity, with chocolate-like sweetness in the middle section, caramel aftertaste and green tea sensation in the finish, with floral and cedar aromas in the aftertaste, overall balanced.

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