What Is Coffee Processing?
If you’ve been following the specialty coffee world for a while, you’ve probably noticed the term “process” on coffee bags. Often times, the process will be washed/wet and occasionally it is dry/natural. But, there's also a process referred to as honey process. If you're new to coffee or aren't familiar with the agricultural side of coffee then you might be wondering what all this means and how it affects your cup of coffee?
After picking the cherries from the coffee trees, the coffees are brought to the processing mill where the farmers or processors separate ripe cherries from unripe. They do this by dumping the cherries into water. The ripe cherries are more dense and therefore sink. Unripe cherries, overripe cherries, and other organic matter are less dense and therefore float. These “floaters” are typically used for internal consumption, that is, for selling within the country of production as opposed to exporting. In the best case scenario, the “floaters” don’t get processed with the ripe coffee.
Once the ripe cherries have been separated, the processors have some options which brings us to the various processing methods that could be chosen at this point:
Dry/Natural Process: With this method, the farmer doesn’t remove the skin. They leave the cherry intact. This process is called Dry because the coffees aren’t washed at all. The coffee seed (bean) is allowed to ferment within the fruit. This process works very well in arid regions where the sun can dry the coffee within about four weeks. After the coffee drys, the processors “dry mill” the coffee, which strips the dried skin off of the bean. This process allows for a lot more complexity of flavor because of the fermentation it undergoes within the fruit. This process can be tricky though. If the atmosphere is too wet, the coffee can mold. This process can also cause the coffee to taste overly fermented. Many farmers opt for the wet method (see below) because it is safer and more consistent.
Honey Process: In this process, the pulp (outer skin) is removed. After the pulp is removed, the inner skin (a.k.a. the mucilage, or honey, due to its stickiness) is left on the bean and allowed to dry and slightly ferment on the bean. Honey processed coffees are significantly less fermented/less acidic than wet or dry coffees and slightly more fermented/more acidic than pulped natural coffees. One main factor in what a honey processed coffee tastes like is the amount of mucilage, or “honey” left on the bean. Another factor is the amount of drying time/exposure to light the coffee receives. Farmers have even begun to designate color names for the different honey processes: Yellow, Red, Black, in the order of more to less exposure to light, which means shorter to longer drying times. The benefit of honey coffees is that farmers can approximate the flavor complexity and sweetness of natural/dry coffees without such a high risk of overfermentation or molding.
Natural Pulp Process: This process is sometimes known as semi-dry. That’s because the coffees are depulped (skin removed) by “pressure washing” and then set out to dry without any mucilage. It basically looks like a washed coffee except that it isn’t allowed to ferment. These coffees are very simple and consistent but potentially very bland.
Wet/Washed Process: This is perhaps the most popular process. It is the safest process that allows for a good amount of complex flavor and sweetness without a high risk of over fermentation or molding. Basically, the depulped cherries are stored in water tanks, or “fermentation tanks”, where the coffee (still covered in its mucilage) does ferment, but in the process of fermentation the coffee sheds the mucilage, which is eventually washed or rinsed off. This process can use an exorbitant amount of water, and there are folks working to use less water during this process. This process tends to wash the more powerful flavor notes off the coffees and reveal the more subtle notes. It also tends to produce coffees with high levels of citric acid, hence the brightness and crispness.
- pros: complex fruit characteristics
- cons: potentially less stable over time
- pros: maintains crispness and brightness of a wet coffee while also allowing for the more complex flavor profiles of a natural coffee
- cons: can incorporate the “dirtiness” of a natural coffee and lack the brightness of a wet coffee
- pros: little risk for mold and over-fermentation
- cons: bland or overly wheaty
- pros: clean, bright, crisp, straightforward
- cons: can lack complexity and depth
One crucial thing to keep in mind is that the way a coffee is processed, however important, is not the only factor in how a coffee will taste. Nevertheless, be sure to pay attention to the process when purchasing coffee. It may just help you decide which coffee to choose.