Processing Coffee Beans

Let's first talk about the structure of coffee berries!

Coffee seeds, also known as "coffee beans", are wrapped in many layers like cocoon, with the fruit in the center. The outermost layer of a coffee bean is a glossy skin, and underneath is a thin layer of slightly transparent pulp. On the inside of the pulp are two seeds covered by a membrane of the endocarp. The outer layer of the seed is covered with smooth and mucous pectin.

The endocarp is the innermost pulp layer, which contains the entire coffee bean (with a silver skin attached to the surface).


Green Coffee Bean Processing
Once the ripe coffee cherries are picked, they need to be dried to extract the beans.

The treatment method has an important influence on the aroma of coffee beans. At present, there are four common treatment methods on the market: dry treatment, wet treatment, honey method, and anaerobic treatment.

Dry or Natural Method
Spread the coffee cherries on the drying field or on a ventilated raised bed. The thickness of the spread is about the height of 2 coffee cherries. To ferment evenly, the coffee cherries need to be turned at timed intervals. Covered with a tarp at night to keep out night dew. During the drying process, the moisture content of fresh coffee cherries gradually decreases from 70% to 15%-30%, and then to 10%-12% (this is the ideal moisture content for preserving coffee beans).

In about 2-4 weeks, the water content drops to 12% and the beans become hard. Then a sheller tool is used to extract the beans from all the layers covering them.

Advantages and Disadvantages
Properly treated sun-dried beans will absorb the fructose essence during the drying process, with a strongly fruity aroma, heavy sweetness, and a body that is better than half-washed or washed beans. The disadvantage is that the sourness of sun-dried beans is slightly lower. The quality of the beans is greatly affected by the weather. This method is most afraid of rain and dampness, which will cause the fruit to grow mold, contaminate the beans, and in some severe cases have a sour vinegar and earthy smell.

Wet or Washed Method
First, the lower quality beans, the ones that float on the water, are sieved from the large water tank. Then the red fruits and fast-ripening green fruits that sink to the bottom of the tank are moved to the large or medium-sized pulp sieving machine. After removing the sticky shell beans, they are moved into a large sink, and then the most important washing and fermentation process is carried out to remove the pectin layer on the shell beans.

The pectin layer is difficult to wash away with water. It needs to be hydrolyzed with various bacteria in the water tank to decompose the pectin into pectin acid, and then continuously stirred and washed. The fermentation process takes about 16 to 36 hours, depending on the temperature and humidity. The coffee beans are then washed and dried.

Advantages and Disadvantages
The color of the washed beans is blueish green, the beans are beautiful in appearance, and the coffee is of the highest quality. Washed beans have a better sour flavor and lift in the taste. It has the best fruit flavor and fruit acidity and thus the taste comes out clean. On average, it takes 2-10 kilograms of purified water to wash 1 kilogram of coffee fruit, and only 200 grams of coffee beans can be taken out of 1 kilogram of fruit. Water-scarce regions cannot afford such water-intensive bean extraction.

Honey Method
Pour the red fruit into the pulp scraper, take out the shell beans covered with pectin, remove the coffee pulp, and keep the pectin layer for exposure. Treatment method: white honey treatment only retains 10% to 20% of pectin, and gradually increases, and black honey treatment retains 100% of the pectin layer, and then it is exposed to the sun until the water content drops to 12%. The beans have a taste somewhere in between the previous methods mentioned. There are layers to the taste from fruit acidity to a bit of sweetness in the flavor.

The sour taste of the fruit is lower than that of washed beans, but higher than that of sun-dried beans; the sweetness is lower than that of sun-dried beans, but the clean flavor is better than that of sun-dried beans.

Anaerobic Method
The anaerobic fermentation treatment method of coffee beans refers to the brewing technology of wine. Add carbon dioxide to the stainless-steel fermentation tank, squeeze out the air, let the coffee beans ferment in an anaerobic environment, reduce the sugar decomposition rate and the pH value drop rate in the pectin of the coffee beans, so as to obtain higher sweetness and better quality and unique flavors. This is the most widely known method of anaerobic fermentation - carbon dioxide maceration, also known as "red wine processing".

This treatment method is different from the general sun drying method, which easily causes excessive fermentation of the fruit.

Anaerobic fermentation can precisely control the fermentation time to avoid over-fermentation. Therefore, it can obtain a fuller aroma and bolder taste than the traditional processing method. The coffee beans produced have a fuller body and a brighter wine aroma. Lower acidity, higher sweetness.

However, this treatment method lacks some regional flavors. No matter where the beans are purchased, as long as they are anaerobic fermentation, the main tone is basically the same.

SATURNBIRD Coffee has strict quality requirements. In the selection of coffee beans, SATURNBIRD Coffee carefully selects high-quality Arabica coffee beans, which is different from the production process of traditional instant coffee. Traditional instant coffee is roasted and then extracted. Finally, the coffee liquid is made into freeze-dried coffee by the principle of hot drying. In this way, the coffee flavor will be lost due to the evaporation of thermal processing.
However, the production method of SATURNBIRD Coffee is to roast the coffee beans in 6 levels, and then extract them into coffee liquid. The point is that SATURNBIRD Coffee freeze-dries the coffee liquid to make it freeze-dried coffee. SATURNBIRD freeze-dried coffee can be quickly dissolved in water, and at the same time, it can restore the flavor of coffee to the greatest extent.
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