Learn about coffee from picking to processing

People did not "drink" coffee at the beginning, but "ate" it. In other words, they directly ate the fruits of the coffee tree (called coffee cherries because the size and color of the fruits are like cherries). To be more precise, they ate the coffee pulp (coffee seeds are too hard, so of course they are spit out directly).

Let’s talk about the coffee process from picking to processing!

The structure of coffee cherries

After coffee cherries are picked, they need to go through a series of processes before they can become what we call green coffee beans. This series of processes is what we often call the processing of green coffee beans or the rough processing of green coffee beans in the industry.

From the outside to the inside, the coffee cherries are:

❼ Peel (exocarp)

❻ Flesh (mesocarp)

❺ Pectin

❹ Parchment (endocarp)

❸ Silverskin (the thin layer between the parchment and the green beans, including the center line)

❷ Green coffee beans (endosperm)

❶ Center Line

Note: Silver Skin/Chaff: There is a thinner film inside the parchment paper that wraps the coffee beans. Because of its shiny and silvery color, people usually call it "silver skin". This layer of silver skin will fall off during roasting. Usually when you grind coffee, you will find some silver fragments in the coffee powder. These fragments are the silver skin that failed to be separated from the coffee beans during roasting.

There is a sentence in Coffee Coffee that if we roast and heat the coffee beans, the dry (sun-dried) coffee beans will peel off a lot of silver skin, while the washed coffee beans will peel off much less. When we look at the central concave line of the roasted coffee beans, if a lot of white silver skin is retained, it is more likely that the washed coffee beans are processed.

Water content

The water content of washed coffee is 12%~13%, while the water content of dry (sun-dried) coffee is 11~12%. Generally, coffee beans have different colors due to their different water content. Coffee beans with higher water content are green or cyan, while those with lower water content are brown or nearly white. Therefore, washed coffee beans have a darker green color.

Is the silver leather intact?

The washed refinement method generally removes the silver skin on the coffee beans during the processing, giving them a special luster, but the dry refinement method only removes the coffee shells, leaving the silver skin intact.

Roasting degree

Generally speaking, the darker the roasting degree, the less regional flavor the beans themselves will have. At the same time, its taste will become heavier. Therefore, roasters will selectively choose the roasting degree according to the quality of the raw beans and the production method. If you get a good quality bean with a floral, fresh fruity and sour flavor, then choosing a light to medium roast can well preserve its high-quality regional flavor. But if you get a raw bean of poor quality, improperly stored, out-of-season beans. Because the longer the coffee beans are stored, the flavor will slowly dissipate in a bad storage environment. At this time, you can speed up the roasting rhythm, extend the caramelization time, and appropriately deepen the roasting degree to show its taste.

Although the silver skin of dry coffee beans is intact during processing, it disappears after roasting. Usually, workers will keep the parchment on the surface of the green beans to protect them, but sometimes the industry will choose to remove the parchment before drying to speed up the drying process. Obviously, the latter is completely pursuing economic benefits rather than quality.

Some producers retain the parchment until it is sorted and shipped. The choice of drying method is usually limited by efficiency.

Sun-dried beans have more silver skin on the outside, which is removed more thoroughly during roasting, so less is needed during grinding; washed beans have more silver skin on the inside, which will remain after roasting, so more will appear during grinding. Of course, it is directly related to the degree of roasting. The deeper the roasting, the cleaner the silver skin is removed.

Too much silver skin will make the coffee taste astringent, but if the silver skin is over-processed on the raw beans, the flavor will be reduced.

Moreover, there is definitely silver skin in the center line of washed beans, but the problem is that part may not produce obvious astringency, so don't pick out the silver skin completely~

In general, not removing the silver skin will make the coffee a little bit astringent but it will not affect the overall taste of the coffee.

▼ Ripe coffee cherries (left) and half-cut coffee cherries (right)

▼ Separating the peel and flesh (right), and green beans with pectin and parchment (left)

Note the yellowish transparent pectin on the left side, the S-shaped yellow in the middle is the silver skin that wraps the beans from the inside out, and the parchment shell is between the silver skin and the pectin. The skin and flesh on the right are one, and the flesh of some coffee cherries is slightly thicker. Ripe coffee cherries are sweet when bitten, and have a spicy taste of green pepper and spices.

▼ The picture below is an enlarged picture of green coffee beans with pectin, in which the pectin, parchment, silverskin and green beans are clearly distinguishable.

【Coffee Cherry Picking】

• The coffee cherries are harvested one by one. The clusters of cherries must not be picked off, and the stalks behind the cherries must not be pulled off.
• Pick all red fruits, do not pick green fruits or half red fruits

• After harvesting the fruit, shade should be provided to prevent sun exposure.

Fresh fruits are harvested on the same day and processed within 8 hours. If processing is not possible on the same day, the fruits should be poured into a fruit storage pool and soaked in clean water to preserve their freshness.

After the coffee cherries are picked, they need to go through a series of processing steps before they can become what we call green coffee beans. The processing is done by removing the exocarp, pulp, endocarp, silverskin, etc. of the coffee cherries, and finally obtaining green coffee beans. This series of processes is what the industry calls rough processing of green coffee beans, or in layman's terms, it is the way green coffee beans are processed.

【Processing Method Classification】

Coffee cherries are processed in two ways: dry processing and wet processing, depending on whether the skin is removed. Depending on the treatment of pectin, there are more detailed methods such as honey processing and semi-washing.

Dry Processing

Dry treatment is the most primitive treatment method; compared with wet treatment (water washing method), it requires less equipment, water source, and manpower, and the treatment method is relatively simple. It covers the following different methods:

▶ Sun-Dried / Natural

▶ Pulped Natural / Honey (Miel)

Sun-Dried or Natural

As the name suggests, sun-dried means that the coffee cherries are completely dried in the sun.

A good sun exposure regimen should include:

❶ Winnowing: remove light impurities, branches, leaves, grass, etc.;

❷ Sifting removes impurities that are heavier or larger than coffee cherries, such as stones, dirt, etc.

❸ Flotation: Further remove impurities and over-ripe or even dried coffee cherries based on their specific gravity.

What we actually see in Ethiopia is that after the coffee cherries are picked, they do not go through the flotation process, but are directly spread out on drying beds. Workers then go to inspect and remove over-ripe or unripe coffee cherries, as well as remaining impurities (twigs and leaves, etc.) before the coffee cherries dry and turn black.

Pulped Natural

A processing method originated in Brazil (1991). Some people call it Semi-washed, and it is classified as semi-washed, but I personally prefer Semi-Dried (because the coffee cherries are sun-dried without the peel and pulp, and they do not enter the subsequent washing process).

Method: The peel and pulp are removed by machine, and the pectin is retained for sun drying. The reason for this method is to make up for the lack of effective grading and screening of coffee fruits of different maturity in the sun drying method, which affects the quality of the final coffee beans.

For example, the way the sun-dried honey is processed in the Aimani Estate in West Java. The fruit is picked manually to ensure its stability. After picking, the outer peel is removed and the fruit is sun-dried while retaining the flesh, which is also called peel-free sun-drying. After about a month of sun drying, the beans are washed and then stored for about half a month before packaging. The only purpose of this process is to create a more complex and fuller taste.

Honey (Miel) Processing

Honey processed coffee is like adding honey and brown sugar to your coffee, and generally the more mucilage left on the beans, the sweeter the flavor.

Honey processing is currently a popular processing method. This processing method is closely related to Costa Rica. Central American countries such as Costa Rica and El Salvador are good at using this processing method.

Its processing method is basically the same as Pulped Natural, but the difference is that it is divided into different categories according to the proportion of pectin retained and the drying method:

▶ 80%-90% of the pectin in White Honey has been removed.

▶ Yellow Honey retains 50% pectin and is not fermented. It receives the most light and dries for about 8 days.

▶ Red Honey Red Honey removes 25% of pectin and is not fermented. Sun drying lasts about 12 days, and a shade shed may also be used during the process

▶ Black Honey basically retains all the pectin. It is dried at a slightly higher temperature at low altitudes. It is covered and slightly fermented for the first 24 hours. The rest of the drying process is transferred to the African drying bed for drying.

▶ Gold Honey basically retains all the pectin, is dried at high altitude and low temperature, and prolongs the drying time.

For example, this one comes from the Šumava estate. The owner, Francisco Men, has retained most of the original forests in the park to maintain the ecological balance of the estate, showing a rich fruity aroma and high sweetness. Use V60 to brew [Costa Rican Black Honey], 15g beans, water-to-powder ratio 1:15, grinding size sugar size, brew to 225g, steam with 37g water for 30 seconds, in the first stage, use medium water flow to brew 120g, brew out the floral and berry aroma in the front and middle stages, and in the second stage, use large water flow to brew out the strong black tea feeling. When tasting, the tomato acid is obvious, the berry acid is soft, retaining the bright and delicate citrus acid and the low raisin, nutty aftertaste, and the sweetness is strong.

At individual estates, the treatment of individual batches will vary.

Brief summary:

Sweetness: black honey > red honey > yellow honey > white honey

Cleanliness: White honey > Yellow honey > Red honey > Black honey

Balance: Red honey/yellow honey > black honey/white honey

Wet Processing

▼It is divided into two types: Semi-Wash and Full-wash.

The final product of both methods is: green coffee beans with parchment paper.

The main difference: whether to remove the pectin layer directly by machine or through a fermentation tank.

Semi-washed: After the coffee cherries are peeled and pulped, they are not passed through a fermentation tank, but through a special pectin removal machine to remove the pectin.

Fully washed: After the coffee fruit is peeled and pulped, it enters the fermentation tank and ferments for 1-2 days (the time varies depending on the temperature and humidity on site) to remove the pectin layer. The fermentation method is further divided into water and anhydrous, with enzymes and without enzymes.

Wet-Hulling

Wet planing is common in Indonesia and is different from the more common washed and natural methods.

The inner pericarp of washed, honey-treated or sun-dried beans is retained until the beans are dehydrated and hardened, and the moisture content drops to 12%, or is sealed and stored and matured for 1-3 months before being ground off.

However, the wet hulling method removes the inner peel when the beans are moist and soft, with a moisture content of up to 30-35%, exposing the surface of the raw beans directly, and then continues to dry them. This is because the climate in Sumatra is humid, and this method was developed based on local conditions to accelerate drying. The drying time is shortened, the fermentation period of the coffee beans is shortened, the acidity is greatly reduced, the body is increased, and the caramel and fruity aromas are obvious, with a slight woody and herbal flavor, which is also the unique "regional flavor" of Mandheling.

For example, Tiger Mandheling, Tiger Mandheling grows on a hillside at about 1,500 meters. The humid tropical rainforest climate brings abundant rainfall, and the volcanic soil brings nutrients. But because it is humid all year round, the [wet planing method] is used to shorten the drying time, use 88~89 degree water, sugar particle size, Kono filter cup brewing, water-to-powder ratio of 1:14, steam for 30 seconds, and then brew in one step. It has a distinct dark chocolate and cream taste and high cleanliness.

【Comparison of Processing Method】

▼ Impact on the environment

[Characteristics of various green bean processing methods]:

Acidity: Washed > Semi-washed > Honey Processed > Wet Hulled > Sun-dried

Sweetness: Natural > Honey > Wet-shaved > Semi-washed > Washed

Production risks: wet hulling/ natural > washed/ honey processed > semi-washed

Equipment cost: Washed/ Semi-washed > Honey processed/ Wet hulled > Sun dried

Water usage: Washed > Semi-washed > Honey treatment / Wet hulling

In addition, the coffee producing area, coffee growing environment, and coffee variety are all important indicators that affect the quality of coffee. Suitable altitude, soil, rainfall, and sunlight help to form ideal coffee beans.

The relationship between coffee beans and varieties

There are two main types of coffee beans: Arabica originated in Ethiopia and is regarded as high-quality coffee; Robusta originated in Congo and is generally used to make instant coffee or affordable coffee.

There are huge differences in the environments in which these two major coffee types are grown. Robusta is easier to grow on farms and has a higher yield. Arabica accounts for more than 60% of the world's commercial coffee production, but Arabica beans cannot grow in harsh climates, resulting in huge differences in flavor and taste. Robusta beans have a stronger bitter taste than Arabica beans and have a 40-50% higher caffeine content.

The relationship between coffee beans and altitude

The altitude at which coffee beans grow is closely related to the taste of the coffee beans. Coffee grown at higher altitudes tends to be of higher quality, and high-quality coffee has a more complex flavor than coffee grown at lower altitudes. Generally speaking, the higher the altitude, the higher the density and hardness of the coffee beans. The altitude will allow the coffee beans to better exert a complex and subtle taste, so the beans will be more expensive.

The relationship between coffee beans and production areas

There are more than 60 countries producing coffee in the world, and each producing area has its own unique regional characteristics. Even in the same area, the flavor of the coffee grown may not be the same. If the coffee information on your coffee bag is not clearly described or the barista cannot tell you where the coffee was grown, then this may not be an ideal coffee bean.

A cup of excellent coffee must be one that has been strictly controlled in terms of quality. In addition to the factors affecting the coffee producing area, coffee growing environment, and coffee variety mentioned above, an ideal coffee bean is also closely related to the later processing of the coffee beans introduced above.