How coffee is processed has an important effect on the coffee flavor and aroma. Find out more about the different coffee processing methods in this article.
From the time when coffee is planted to when the beans are packaged and sold, various production processes take place. One of the most important steps in coffee production is coffee processing. This is because the method of processing has a significant effect on the flavor of the end product.
Apart from traditional methods such as wet and dry processing, farmers have also started to experiment with new methods such as anaerobic fermentation.
I’ve compiled a short overview of how coffee is processed for those who are interested in learning about the various steps coffee goes through before it lands up in their cups.
What Is Coffee Processing?
Coffee processing is where the coffee seed, or bean, is separated from the fruit flesh and skin of the cherry. The coffee cherry actually consists of multiple parts that are either removed or retained during the different stages of coffee processing, depending on the method used. The parts include:
- The outer skin, which is also called the exocarp
- The thin layer of flesh that lies directly underneath the outer skin, which is called mucilage
- The skin that covers the coffee seed, which is called the parchment or endocarp
- The coffee seed or bean, which is the part of the coffee cherry that we use to make coffee
How Coffee Is Processed – Traditional Coffee Processing Methods
There are three traditional coffee processing methods:
Natural or dry processing is the oldest coffee processing method. It’s typically used in areas where water is a scarce commodity, such as in Ethiopia and Brazil. Areas that are humid or experience a lot of rain are not ideal for the dry processing method.
With this method, the coffee cherries are harvested when they’re ripe and laid out on large drying stations, which, depending on the farm or region, can be raised beds or brick patios.
The cherries are then left to dry in the sun until their moisture content drops to around 11%. Some farmers also use machines for drying out the beans. The length of the drying process will depend on variables such as climate and altitude.
However, care must be taken to avoid the cherries from spoiling. Farmers, for instance, rake and turn the cherries throughout the day and cover them at nighttime or when it rains. Once dried, all the outer layers of the cherry are removed by a hulling machine.
Coffees that are naturally processed tend to have more intense fruity and sweet flavors. Common flavor notes include tropical fruits, honey, blueberry, and strawberry.
Washed or wet coffee processing is the other main processing method. With this method, the fruit flesh is removed before the beans are dried. Since it requires a lot of water, this processing style is not viable in areas where there’s a shortage of water.
Once harvested, the cherries are immersed in water to find the bad or unripe fruit, which floats on top of the water, while the ripe fruit sinks. The cherries are then pressed through a screen to remove the skin and most of the pulp.
To break down the remaining pulp that is still attached to the parchment, the cherries are then fermented in tanks for anything from 8 to 36 hours, depending on factors such as the temperature and concentration of enzymes. Once the beans feel rough to the touch, fermentation is halted by rinsing them in freshwater.
The coffee beans are then laid out on patios or raised beds to be dried until they reach the desired moisture content. As is the case with the dry processing method, the beans are raked regularly to prevent the growth of mildew.
Coffee that’s produced using the wet method has a cleaner cup profile and bright and acidic flavors. Although this process requires a lot of water, it's a popular method among farmers because of the reduced risk of defects.
The honey process, also referred to as pulped natural or semi-washed, is commonly used in Central American countries such as El Salvador and Costa Rica. Before the cherries are dried, they are de-pulped by a de-pulping machine, after which some of the flesh still remains on the beans. As with the dry and wet methods, the beans are then laid out on drying tables or patios to dry in the sun.
Since the beans are covered by less flesh, over-fermentation is less likely to occur. However, the coffee that’s produced through this process has fruity and sweet flavors, such as what you get from the dry processing method. Depending on how much flesh is left on the bean after de-pulping, honeyed coffee is classified as yellow, red, white, or black.
The beans that have the most flesh left after de-pulping are black in color. For this reason, the processed coffee resulting from these beans is referred to as black honey.
The flavors of the coffee that’s produced through the honey process are dependent on how much flesh is left on the bean before drying. Whereas black honey typically has intense fruity flavors, white honey — which refers to beans with the least amount of flesh left after de-pulping — tends to mimic the flavors of washed coffees.
FAQs About How Coffee Is Processed
What Are A Few Alternate Coffee Processing Methods?
Anaerobic: This is one of the newest methods used for coffee processing. It is similar to the wet/washed process. However, fermentation takes place in fully sealed tanks where no oxygen is allowed to enter. The result is a coffee with unexpected and wild flavors.
Carbonic maceration: This method was originally used for wine-making. It is similar to the anaerobic process, except for the fact that the cherries are intact and whole when they are placed in fermentation tanks. This means that the beans absorb all the flavors from the fruit flesh, resulting in coffee with deep and intense flavors.
What Is The Wine Process?
This wine process is a variation of the natural process. It involves leaving the cherries on the shrubs to over-ripen before they are harvested. Such cherries have a higher concentration of sugar once they are harvested than those that are plucked at the peak of the harvest.