Let's discuss one of the things that most deeply affects coffee flavor: Processing! From washed or natural, to honey or anaerobic, let’s talk about what different processing types are and how they affect the flavor of your brew! Broadly, processing refers to the way beans are separated from the coffee cherries and handled before being shipped to roasters. Let’s dig in!
Washed process coffee is likely the most common type of processing you’ll find. First, the cherries are placed in water for sorting. Ripe cherries will fall to the bottom while unripe cherries will float at the top. The unripe cherries are then removed. Next, a depulping machine removes most of the cherry and pulp around the coffee bean. Beans are then fermented in water for a length of time that depends on the climate/temperature. Finally, the beans are either air dried or mechanically dried before being packaged for shipping.
Washed processing tends to lead to a balancing of the flavors in the bean. These beans tend to be easy to brew as they have a larger margin for error that flavor sweetspot. They also tend to be great candidates for superautos (as long as they’re not too dark).
Natural processing sees the coffee cherry left on the bean during drying. The cherries are usually laid out on racks or tables and periodically turned to prevent rotting or molding. After a varying period of time the dried flesh of the cherries are removed and the beans are rested before being packaged for transport.
Natural coffees have more flavors imparted on them by the cherry, and are therefore more flavorful than washed process beans. They tend to work best in a pour over, and often feature stronger berry and fruit flavors (as you would expect from the cherry drying around them). That said, a natural-processed coffee can still taste great in a superauto or other brew method.
Honey processed beans are handled in a manner similar to natural processing. Instead of leaving the entire cherry on the bean, the cherries have a certain amount of pulp removed prior to drying. The amount removed varies and can be determined by the different types of honey processing. Generally “darker” colored honeys (i.e., black honey) were dried with more fruit on the bean. By contrast, white honey processed beans have more of the fruit removed before fermentation.
These coffees tend to offer more sweetness than a washed coffee but aren’t quite as strong as a natural. They tend to make a great pour over but can work in other brew methods as well.
Anaerobic processing is a newer form of processing similar to a washed process. The difference is that the fermentation step occurs in an oxygen deprived tank instead of in a more open water tank. The result tends to be more wild flavors than what you find in washed or natural processed coffees. This method of processing can also help elevate the flavor profiles of beans typically deemed unfit for specialty coffee. It’s an exciting prospect that is already resulting in producers developing delicious coffees who have not typically been considered by specialty roasters.
Swiss Water Process
Removing caffeine from coffee is often done using solvents or other chemicals. However, specialty decaf is becoming more prevalent with the rise of Swiss Water Processed decaf. SWP uses caffeine’s water solubility to remove it. The process is to soak the green coffee beans in hot water, which causes the caffeine to dissolve from the beans. Other water soluble elements like sugars and oils are also dissolved, but the water is then passed through a charcoal filter. This filter catches the larger caffeine molecules and lets the sugars and oils back through into the water.
This infused green water is then used for the next batch of green coffee, preventing those desired soluble molecules from dissolving into the already sugar and oil rich water. It sounds complex, but ultimately it results in decaf that offers more flavor that’s closer to non-decaffeinated coffee in taste.