Coffee Bean to Coffee

A cup of coffee requires a process from planting coffee trees to flowering and fruiting, from picking fruits to peeling green beans, then roasting the green beans into ripe beans, and finally grinding, brewing, and serving them to your table.

Coffee bean picking

Coffee is usually picked by hand, either by pulling all the berries off the branches at once, or by picking them selectively. The latter method is more expensive and is only suitable for picking Arabica coffee beans.

Green Coffee Processing

After the coffee cherries are picked from the tree, the outer skin, pulp and pectin must be removed. This process is called green bean processing. There are different ways to process green coffee beans, which largely determine the taste and quality of the coffee. Today we will popularize the common green bean processing methods.

Sun treatment

Sun drying is a traditional method of primary processing of coffee beans. Currently, ancient coffee bean growing countries such as Ethiopia and Yemen still almost entirely use the sun drying method to process green beans.

The sun-drying method first spreads the ripe or half-ripe beans on the bean drying field for natural drying. The specific time depends on the local climatic conditions and generally takes two to four weeks.

When the moisture content of the coffee beans is reduced to 12%, use a shelling machine to grind off the dry and hard pulp and silver skin.

The sun-drying method has very high requirements for the climate. If it rains during the sun-drying process, the beans will become damp and moldy. The color of sun-dried beans is yellowish when they are raw, and the center will be brown after roasting, instead of the white color of washed beans.

Sun-dried beans have a better sweetness and body, and less acidity, but the quality is less stable and can fluctuate greatly. As the cost of sun-dried coffee is lower, it is widely used not only in Ethiopia and Yemen, but also in Robusta coffee grown in Africa and Indonesia.

Half sun treatment

In order to improve the quality of its own coffee, the Brazilian government invented the semi-sun drying method and has vigorously promoted it. Currently, almost all of Brazil's fine-grade coffee beans are processed using the semi-sun drying method. It can be said that the semi-sun drying method has successfully improved the overall quality of Brazilian coffee.

The preliminary processing method of the half-sun drying method is almost the same as that of the water washing method.

Bean selection: First, put the coffee berries into a large water tank, remove the floating berries, and then put the sinking berries into the pulp screening machine to remove the pulp. It is better to remove the unripe berries, and more importantly, when the coffee beans are sun-dried, they are no longer with pulp, but only wrapped with a layer of pectin, which is more conducive to controlling the subsequent fermentation process.

Drying: Move the beans to the bean drying field to dry. It will reach a certain degree of dryness in about 3 days.

Drying: Use a dryer to further dry the beans until the moisture content reaches between 10.5% and 12%.

Polishing: The beans are finally polished before being bagged and exported.

Since the semi-sun drying method has certain requirements for climate and technology, it is only widely used in Brazil. Through the semi-sun drying process, the unique sweet taste of the sun drying method is retained, and the taste of mold in the sun drying method is avoided, thus shaping the unique flavor of Brazilian coffee.

Washing treatment

The washed coffee method began in the mid-18th century. The washed process first removes the pulp of the coffee fruit (red cherry), then uses a fermentation tank to remove the mucous membrane remaining on the inner skin, and then washes the beans and dries them. The difference between the non-washed method and the washed method is that the non-washed method removes the pulp after drying, while the washed method removes the pulp before drying.

The washing method can remove impurities (stones or garbage, etc.) and defective beans through each step, so the appearance of the green beans is uniform, generally considered to be of high quality, and the trading price is higher than that of coffee beans refined by the natural drying method.

However, the more detailed the division of labor, the more procedures there are for operation and sanitation management, and the higher the risk. Therefore, washed coffee does not necessarily mean high quality. The biggest disadvantage of washed coffee is that coffee beans are easily contaminated with fermentation odor during the fermentation process. Some coffee experts point out that "one coffee bean with fermentation odor will spoil 50 grams of beans." The beans are stained with fermentation odor, mostly because the fermentation tank is not managed and maintained. Soaking coffee beans with mucous membrane on the inner peel in the fermentation tank for one night can remove the mucous membrane. However, if the microorganisms in the fermentation tank change, the coffee beans will be stained with fermentation odor.

In addition, the equipment cost of the coffee washing method is relatively high, and the washing step is also quite laborious, which increases the production cost relatively.

Water washing steps:

1. Bean selection: Place the harvested fruits in a water tank and soak for about 24 hours. The ripe fruits will sink, while the unripe and overripe fruits will float and can be discarded.

2. Remove the pulp: Use a machine to remove the peel and pulp, leaving only the coffee beans wrapped in the inner peel. At this time, there is still a layer of mucous membrane on the outside of the beans, and the water washing process is to clean this mucous membrane.

3. Fermentation: The adhesion of the mucous membrane is very strong and it is not easy to remove. It must be placed in the tank for about 18-36 hours to ferment and decompose the mucous membrane. There are two methods of fermentation, namely wet fermentation and dry fermentation. As the name suggests, the former adds water, while the latter does not. During the fermentation process, the seeds and the internal pulp will undergo special changes. This is the step that most affects the flavor of coffee in the water-washing method. Some farms will add hot water or alcohol to speed up the fermentation process, which will have a negative impact on the quality of coffee beans and is not popular among select coffee lovers.

4. Washing: Farms that use the washing method must build a washing pool and be able to introduce an endless supply of running water. During the process, the fermented beans are placed in the pool and pushed back and forth, using the friction of the beans and the power of the running water to wash the coffee beans until they are smooth and clean.

5. Drying: After washing, the coffee beans are still wrapped in the endocarp, with a moisture content of 50%. They must be dried to reduce the moisture content to 12%, otherwise they will continue to ferment and become moldy and corrupt. The best treatment method is to use sunlight drying, although it takes 1-3 weeks, but the flavor is excellent and quite popular. In addition, some places use machine drying to greatly shorten the processing time, making the flavor not as good as sunlight-dried coffee.

6. Shelling: The dried beans can be stored in a warehouse or sent to a factory for shelling to remove the endocarp and silver film.

7. Selection and grading: Like natural coffee, washed coffee also has a selection and grading process to remove defective beans and ensure better quality before being handed over to exporters to be sold all over the world.

Semi-washed

The semi-washed method is a relatively new and rare method. This method is only suitable for certain areas in certain countries where there is a long dry period in the climate, and can be used to process local coffee. The coffee produced by this method is sticky, and the mucus is not removed during fermentation in the tank. Therefore, the coffee produced by this semi-wet treatment method contains the characteristics of both wet and dry treatment methods. The acidity, sweetness, flavor, and aroma of this coffee are quite good; the only drawback is that the taste of this coffee is not as strong as the coffee produced by the pure dry method or washed method.

Bean selection: First put the coffee berries into a large tank, and move the red berries and half-green and half-red berries that sink into the tank into the pulp screening machine to remove the pulp and impurities.

Remove pectin: After taking out the coffee beans, there is no need to dry them in the sun, nor to pour them into the water tank for fermentation. Instead, pour them directly into the pectin scraper next to it. Only a small amount of water is needed to mechanically scrape off the sticky pectin crumbs.

Sun exposure: Then take out the green beans with smooth surface and expose them outdoors until the moisture content drops to 12% and then they can be stored in the warehouse.

Wet planing

Wet-Hulling is the traditional processing method for Indonesian Sumatran coffee. When the green beans are half dried and still have a moisture content of 30% to 50%, the husks are removed first, and then they are left to dry in the sun to solve the problem of long drying time. Since the drying time is shortened to two to four days, the fermentation period of the coffee beans is shortened, the acidity is also reduced a lot, but the relative concentration is increased, the caramel and fruity aromas are obvious, and even have the aroma of herbs or grass and wood. This is the unique regional fragrance of Sumatra.

However, the impact of removing the husk early is that the last two layers of protection (note: the four layers of protection of coffee beans: peel, pectin, husk, silver skin) are lost halfway through the drying process, which is like taking off clothes and drying in the sun. Although the wet husk method solves the problem of drying time, the probability of the green beans being contaminated by mold, fungi, and yeast is also greatly increased. But paradoxically, these factors have become the key factors in creating the special aroma of Mandheling.

Another characteristic of the wet hulling method is the high probability of the so-called "sheep's foot beans". Since the green beans are hulled by the huller when they are still very moist and semi-soft, the fragile soft and wet green beans are very easy to be compressed by mechanical force and cracked, broken or scratched on the surface, thus forming the so-called sheep's foot beans and scratched beans, which makes the green beans look worse.

Honey Processing

The so-called honey process (Miel Process in Spanish) is said to refer to the process of making green beans with mucous membranes and sun drying. After removing the outer layer of the coffee beans, there will be a layer of sticky gel. The traditional water-washing process is to wash it off with clean water, but due to water resource restrictions in some high-altitude production areas, this direct sun-drying method has emerged.

The honey processing process is susceptible to contamination and mildew, and requires close supervision throughout the process, constant turning, and accelerated drying to avoid the production of unpleasant fermentation flavors. Its advantage is that it can best preserve the original sweet flavor of ripe coffee berries, giving the coffee a light brown sugar flavor and sweet stone fruit, while the berry flavor also supports the aroma of the red wine base, and is considered a very elegant product.

The popularity of honey-processed coffee beans is largely due to its sweet and thick characteristics, which are very suitable for making espresso in coffee shops. In recent years, more and more coffee beans are called "Miel Process", and they have also become the preferred material of international coffee contestants.

According to the different proportions of retained pectin and drying methods, it can be divided into:

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

Yellow Honey retains 50% pectin and is not fermented.

Red Honey basically retains all the pectin and is not fermented.

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 beds for drying.

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

(Some pictures are from the Internet and will be deleted if there is any infringement)