As you already know, there are three ways of processing coffee, namely by dry, wet, and semi-wet(semi wash) methods. In a previous article, we explained how coffee fruits are processed by dry processing to produce the best coffee beans.
Well, it’s incomplete if you don’t know how to process coffee with the wet method, right? For that reason, we will discuss it this time. Check out the article!
How to process coffee with the wet method
You can enjoy a cup of coffee from a long processing process. Starting from cultivation techniques, post-harvest processing, to the final presentation.
Only from quality beans can a cup of coffee be served on our table, this of course comes from coffee fruit that has been harvested, directly into the processing process. The harvested coffee cherries are sorted and then selected based on certain criteria.
The best quality fruit if processed properly will certainly produce high quality coffee. Well, one way of processing coffee that is also often applied by farmers is processing with the wet method or wet process.
Although the cost of this process is high, the coffee produced is of high quality. However, the natural flavor of coffee can be reduced due to the involvement of water during processing.
This means that wet processing uses water for peeling and washing the coffee fruit. This is different from the dry process, which is dried immediately after the coffee is harvested.
Read also: Dry Process Coffee: Dry Process Coffee
Usually the wet method is used to process Arabica Coffee, and is often applied by large-scale coffee plantations. Although it is possible that many small-scale (farm level) and medium-scale (semi-mechanized and mechanized) implement it.
The stages of processing coffee fruit with this wet method include:
The coffee fruit to be processed by this method must be ripe or red-picked (95 percent red fruit). After harvesting, coffee cherries should be immediately separated between red, green, damaged or rotten coffee cherries, as well as the dirt.
Now, before the coffee is peeled, the coffee cherries need to be separated by size. In this peeling is done using a pulper or fruit skin peeling machine.
In essence, pulping aims to separate the coffee beans from the outer shell and mesocarp (the meaty part). The working principle itself is to release the exocarp and mesocarp of the coffee fruit.
This process also produces coffee beans that have been separated from the skin of the fruit. When finished, the coffee beans will enter the tubs that have been provided to enter the fermentation process.
Fermentation in wet method coffee processing
The next stage of coffee processing with this method is fermentation. This aims to loosen the mucus layer found on the surface of the coffee bean horn skin.
Fermentation is also done to reduce bitterness and encourage a “mild” impression in the flavor of the brewed coffee. The fermentation process itself is done by soaking the coffee beans in a tank of stagnant water for about 12-48 hours.
During this time, the mucilaginous layer consisting of 84.2 percent water, 8.9 percent protein, 4.1 percent sugar, 0.91 percent pectin substance, and 0.7 percent ash will be hydrolyzed by coffee enzymes and similar enzymes produced by microorganisms present on the fruit skin.
For coffee beans that float or are floating in the puddle, they will be taken away because it is coffee with poor quality. The end of fermentation will be marked by the shedding of the mucus layer that covers the horn skin.
In order for the fermentation process to be evenly distributed, the farmers will turn over as often as possible. When this process is complete, the coffee beans are rinsed and washed again using clean water by machine.
The end of fermentation will be considered complete when the seeds are felt and the remaining mucus on the seeds has disappeared.
Coffee beans will then go through a drying process, which is by drying in the sun or can also use a mechanical machine with a hot temperature of 65 – 85 degrees Celsius. The drying itself will usually take about 2 – 3 weeks, until it produces coffee beans with a moisture content in the range of 16 – 17 percent.
Meanwhile, the desired or required moisture content in this process is 12 percent. The level is an equilibrium so that the coffee beans produced, the taste does not change easily and is resistant to mold attack.
When the coffee beans have reached a moisture content of 12 percent, peel off the horn skin that covers the seeds. This stripping can be done by pounding or utilizing a machine. huller or peeling machine.
To reduce the risk of damage to the coffee beans, farmers will usually use machines. Well, the result of peeling at this stage is called rice coffee beans, or what we know better as green beans.
If a good green bean has been produced, the next wet process coffee processing will be the final sorting process. This aims to separate impurities and damaged seeds. Then, the coffee beans are packaged and stored before being distributed.
The purpose of this process is because the quality of coffee greatly affects the value and selling price of the coffee commodity. Therefore, coffee classification or grading must be done to determine and calculate how good the quality of coffee is.
During the grading process, the quality of the coffee will determine the final quality of the coffee beans produced. Well, the actual green coffee beans still have to go through further processes to be ready for consumption, namely grinding into coffee powder, to packaging.
Advantages and risks of wet method coffee processing
By processing coffee using wet process, there are advantages that can be obtained, namely:
- The resulting coffee product becomes more homogeneous.
- The risk of unwanted fermentation occurring is lower.
- The drying area required is relatively smaller.
- The drying process will be faster.
Behind the advantages there are certainly disadvantages or risks that can be obtained. This method is no exception, such as:
- Washing and soaking water can become contaminated if not changed regularly.
- Will require a very large amount of water.
- The resulting iron content of >5mg/L and high pH of the water can cause off-flavor or tastelessness.
Seeing the explanation about this wet method coffee processing, of course, makes you think that in producing a cup of delicious coffee there is a very long and very strict process.
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