Coffee Processing

What is Coffee Processing?

If you pick up a bag of specialty coffee, you may notice that there will be something about the type of processing on the label of the coffee beans. Processing coffee beans, simply put, is the removal of the outer cherry from the inner coffee bean.

To understand coffee processing, it helps to understand the coffee cherry parts. We’ve included an illustration of the coffee cherry to assist with visualization of the coffee fruit.

A farmer could have grown the perfect coffee cherries only to have them destroyed by poor processing techniques. The processing method has a huge impact on the taste of the coffee. So, in addition to the type of bean, region, and roasting, processing is another challenge to producing excellent coffee beans.

Different processing methods may require different amounts of time, monetary resources, and natural resources. Growers are developing experimental methods to develop different tasting notes in their coffees.

Types of Coffee Processing

The main three methods are natural dry processing, washed or wet processing, and honey or pulped natural processing.

Natural – Dry Processing

Natural or dry coffee processing is the oldest and most basic method of processing the coffee crop. After harvesting the coffee cherries from the trees, growers lay the crop out in the sun to dry. Even though it is a simple process, it is very labor intensive. The methods that producers use to lay the coffee out to dry vary. Processors either lay the coffee cherries out on bricks or stone patio tiles, or on raised tables. The raised tables promote more air flow to dry the coffee cherries more evenly. Coffee processers must turn beans during drying, so they do not become moldy or begin over-fermenting. Drying coffee in a thin layer better controls the fermentation process.

After the coffee has adequately dried, processors mechanically remove the the outer cherry from the bean. Finally, the coffee is bagged and rests for a prescribed time before being shipped.

Ethiopia, Rwanda, and other countries that are in dry climates with an abundance of sun and without easy access to water use natural dry processing for their coffee beans.

Washed – Wet Processing

As the name implies, washed or wet processing requires a lot of water. Over half of the specialty coffee produced in the world uses wet processing. While it is much more expensive than dry processing, it is the preferred way to process coffee, and it requires specialized equipment. Landlocked countries, or countries without access to water, are unable to use this method. Central and South American coffee producers, along with some African producers, use wet processing.

The wet process starts with putting the coffee cherries in water so that any defective beans float to the top and are discarded. The remaining beans are then put through a machine called a depulper to remove the cherry skin and pulp. At this point, there is still a sticky and sweet layer around the bean called mucilage, which is water insoluble.

The beans are put into a vat to begin the fermentation process to remove the mucilage. After a designated amount of time, the fermented beans are to the point that they can be rinsed, and the mucilage can be separated from the bean along with any lingering residue. The length of time that this fermentation stage takes differs by region and climate. Hotter climates will cause quicker fermentation. If the beans are left to ferment too long, it will have a negative effect on the taste of the coffee.

The beans are then laid out to dry as in the natural process, on brick tiles or raised tables. In wet climate areas without enough sun or with too much humidity, the washed coffee may be mechanically dried. The drying process is critical to the quality of the coffee. Overdried beans will break up and are considered defective. If the coffee is not dried enough, the beans are prone to degrade due to fungi and bacteria.

Regions where wet processing is prevalent are Colombia, Costa Rica, Guatemala, Kenya, Java, and Papua New Guinea.

Honey or Pulped Natural Processing

Coffee “honey” is the mucilage. Honey or pulped natural processed beans can be white, yellow, gold, red, or black honey. The color of the honey depends upon how much of the mucilage is removed from the bean during processing. Less mucilage translates into lighter honey and less sugar or fermentation. As in wet processing, the beans are placed in water to remove any of the detective floating beans. The coffee is put through a depulper to remove the outer skin and a portion of the mucilage. Then the beans are dried naturally. Honey processing is used in areas of Central America like Costa Rica and El Salvador.

Effect of Coffee Processing on Taste

The way that the coffee is processed can be tasted in the beans.

Natural Dry Processing Flavor

Dry processing is the oldest form of coffee processing, and the characteristics of coffee beans processed in this way are fruity and sweet flavors. These flavor additions happen regardless of the region that the beans are grown; they are developed purely from the dry processing. Baristas and coffee drinkers have mixed opinions on these added flavors. The addition of winey, fruity flavors can be distracting to the coffee taste for some, while others will love these interesting combinations of flavor notes in their coffee.

Wet Processing

Wet processing imparts a clean acidity to the coffee. Many baristas prefer wet processed coffee because the quality of the coffee tends to be a more stable, less “wild” cup of coffee. If you want consistency in your beans, seek out wet processed coffee.

Honey or Pulped Natural Processing

The taste of honey or pulped natural process is wholly dependent on the color, or the amount of mucilage, left on the coffee parchment (seed). The darker the honey, the more sweetness and fermentation. More fermentation also translates into more riskiness of quality control of the coffee. Too much fruitiness or winey flavor can detract from the bean, and there is the added risk of rotten flavor notes if the beans are overly fermented. The risk may be worth it, however, if a delicious, full bodied, nicely acidic, sweet cup of coffee is the outcome.

Newer / Experimental Types of Coffee Processing

The three processes detailed above are the main processing methods. However, there are some newer, more experimental methods that are used as well.

Anaerobic Processing

Anaerobic processing uses pressurized sealed tanks, without oxygen, during the fermentation phase. The coffee beans may have the whole cherry pulp, or all or a portion of the mucilage removed. After this, the beans are either naturally dried, honey processed, or wet processed. The anaerobic process produces distinctive lactic acids that are not made in other forms of coffee processing. Some common foods that have lactic acid fermentation are sourdough bread, kimchi, pickles, and sauerkraut. These lactic acids add tartness to the flavor of the coffee. Lactic acid also decreases the chance of spoilage from bacterial growth. Anaerobic processing is useful in regions with unpredictable weather conditions. By using the tanks, fermentation can be quality controlled for a more consistent bean.

Carbonic Maceration

Carbonic maceration is an experimental coffee process in which the full coffee cherries are placed in airtight containers and then pumped full of CO₂. Some winemaking uses this same process. The CO₂ injection creates rich, winey, red fruit, acidic flavors in the coffee. This can take months, unlike the faster anaerobic processing. To avoid having high alcohol content, coffee cherry fermentation is done at a low temperature. After the coffee has adequately fermented, it is either wet or naturally dry processed.

Beans and Butter Coffees

If you buy our whole roasted beans, we always include on the label what kind of processing the beans have gone through. In addition to the region and roast, processing will give the consumer further knowledge on what to expect from a given coffee. We invite you to come in and try different beans that have been processed in a variety of ways. You may find that you like the “wilder” processed beans.