Looking at a coffee menu or label on a bag of coffee can often be confusing—so many words in such a small place. There are terms even coffee professionals cannot seem to agree on. For the everyday consumer, it can be difficult to understand. Processing terms like washed, natural, and honey may be familiar to a seasoned coffee professional, but it can be misleading to someone new to coffee. For instance, what does honey mean? Is the coffee dipped in honey? Does the coffee taste like honey?
I once asked a barista if a coffee they were serving was a natural, and it was like I had asked the most profound question. They replied with a puzzled look and said, “all of our coffees are naturally grown.” At first, I thought this was a smart-ass response, but then I got myself thinking. The term “natural” refers to things not made by humans or anything that comes from nature, so in a way, the question was profound, and they were right, and I appreciated their honesty. It just highlighted that, in this day and age of coffee, we need to be talking about the processes, not just the origin or the varietal, but the process.
PROCESSING
Throughout the world, coffee gets processed in different ways. Some methods are used out of tradition, while other factors, such as climate, affect how coffee gets processed. Processing is such an essential and demanding step, and it is a vital part of developing the flavor and character of a coffee. It can make the difference between a coffee tasting sweet and fruity to tasting straight-up rotten.
Every process begins with selecting coffee cherries, ideally at their optimum ripeness. The coffee cherry comprises several layers between the skin and the bean that contributes to the bean’s flavor. These layers comprise the skin, pulp, mucilage, parchment, and silver skin. The purpose of coffee processing is to remove, or sometimes manipulate these layers to influence the flavor profile, dry the bean to the optimal level to get roasted, and to create homogeneity within a particular lot through various forms of sorting.
Over the years, there have been three significant coffee processing categories common in the coffee industry: the washed, natural, and pulped natural processes. A different term may be used depending on what country they are in, but the essential elements of each method and steps are similar, if not the same. In addition, producers have been exploring experimental processing methods that are truly unique and innovative. These include anaerobic fermentation, carbonic maceration, and aqua pulping processes. There are many more to name, but these are some of the more popular ones today. With consumers looking for the next big thing, a desire and interest in unique coffees is creating a demand for exceptional processing.
Washed (Wet) Process
The wet or washed process is the world-standard for coffee processing and is popular in origins where water is not in short supply. Washed coffees derive their flavors from the varietal and the coffee’s terroir (soil, sunlight, temperature, elevation, orientation, rainfall, and the soil’s mineral composition) and not from the processing.
The process begins with picking the coffee cherries at their optimal ripeness. Next, the cherries get sorted by water in a flotation tank. Ripe cherries are heavier and sink to the bottom, while the under-ripe ones float to the top. Next, the floaters get removed, and the ripe cherries go through a pulping machine to remove the cherry or the skin.
After this, they go into a fermentation tank, ranging from 12 to 72 hours, depending on temperature and humidity. Underwater, free from oxygen, the fermentation process breaks down the mucilage cells. After fermentation, the beans, still in parchment, are once again washed to remove any remaining residue before being put out to dry on patios, raised beds, or in mechanical dryers until they are 10-12% moisture content.
Good washed processing results in clean, articulate flavors that are free from processing influences. The goal is to let the bean shine, not to impart other flavors on it.
Natural (Dry) Process Natural process, dry process, unwashed, or natural sundried
Natural processing is the oldest method of processing coffee. This method involves leaving the coffee cherry intact as they get put out to dry in a single layer on patios or raised beds until they resemble prunes instead of fresh cherries. The natural sugars and alcohols inside the fruit cause a natural fermentation inside the coffee cherry’s closed environment, slowly breaking down the mucilage. During this time, the sugars and the sticky mucilage cling onto the beans and develop fruit flavors and make them sweeter. Once the coffee is dry, a machine separates the pulp and the skin from the seed.
The natural process is slow and risky. It requires less water but needs total cooperation from the environment. To ensure smooth drying, it requires plenty of sunlight with little to no rain during the dry phase. Heavy rains can damage the drying cherries make way for mold and other defects.
There is a constant danger of over fermentation, spoilage, and rot. Hence, giving the process the nickname “natty’s” because these coffees can taste nasty when done improperly. Therefore, it is critical to have a skilled eye monitoring the cherries and rotating them constantly to prevent spoiling. The drying process can range anywhere from 3 to 6 weeks for the beans to dry completely.
Natural processed coffees divide connoisseurs’ opinions in terms of flavor; some love them, others despise them. Natural processed coffees are usually more complex, heavier, sweet, and have lower acidity than their fully washed counterparts. Typical flavor notes for a well-processed natural can range from blueberry, strawberry, tropical fruits, and honey. Still, when done improperly, there can be wild and over fermented flavors of rotten fruits, and alcohol-like notes that make the coffee taste boozy.
There is an old saying for natural processed coffee: “one person’s fruit is another person’s ferment.” A person on the fermented side and not a big fan of naturals, however, could respect a well-done natural. It’s hard to argue if it tastes good.
Pulped Natural and Honey Process-
Pulped-Natural and Honey’s are one of the same, but different. This process is a combination of washed and natural processing. First, pulped-natural cherries get picked at their optimum ripeness. They then get sorted in a flotation tank, where the unripe cherries float and get removed. Instead of soaking the beans in a fermentation tank to remove the sticky layer of mucilage, they get immediately put through a de-pulping machine to remove most of the coffee pulp. The beans then get laid out to dry, still containing a layer of mucilage as they dry for the next three weeks. The beans must get closely maintained and rotated throughout the drying phase. Like naturals without the proper care and attention, these coffees have the capacity to over ferment and spoil.
Coffee producers worldwide are experimenting with the fermentation times and the amount of mucilage they leave on the beans. They created the honey process within the pulped-natural process by doing this. The volume of mucilage remaining on the parchment affects the overall sweetness and flavor of the coffee. It also helps name the specific process. The beans with the least amount of mucilage are less sweet and much lighter in color after the drying phase, while the beans with more mucilage result in more caramelization, darker colors, and a much sweeter with fruitier flavors. Honey processes range from yellow honey, red honey, and black honey.
Pulped-naturals fall under the yellow honey process. A well-done honey processed coffee gives the best of both the washed and natural processing methods, producing sweet coffees with sparkling acidity and a creamy body.
Anaerobic Process
Anaerobic fermentation is one of the trendiest methods of processing coffee. This method has been sweeping through the coffee world, especially in the high-end or exotic coffee realm such as competition coffees. While anaerobic processing is essentially the washed process, it is the washed process turned up a notch or two – or three. The freshly picked cherries get immediately pulped, and instead of being laid out to dry on patios or raised beds, the newly pulped beans get put in a hermetically sealed container. The oxygen gets removed when the coffee gets added at the beginning of the process. Valves on the containers keep them free from oxygen seeping in during the process and allow the CO2 to be released as it builds up during fermentation. With no oxygen getting out or getting in, the chemical reactions alter the pH levels, temperatures, pressure, and sugar levels. One of the major benefits of this process it slows the fermentation process, which allows a different spectrum of flavors to express. In a washed process, the controlled fermentation can last anywhere from 12–24 hours on average; anaerobic environment fermentation can take anywhere from 60 to 96 hours or longer, depending on the progress inside the tank.
The flavors are usually much more complex and expressive. There is an enhanced sweetness and acidity, creating a vibrant coffee that sparkles in the mouth.
Carbonic Maceration
This method is like the anaerobic and nods to the winemaking world. The most significant difference to the anaerobic process is that the freshly picked cherries get fermented as a whole, like with natural processing, and the process breaks down the cell walls of the fruit flesh from inside out. All the unique flavors from the fruit flesh absorb into the beans during the fermentation process.
In this method of coffee processing, the coffee cherries get rinsed, separated by density, and placed in containers. Carbon dioxide gets used to expel oxygen and other atmospheric gases; the containers get purged and sealed using lids with a one-way valve, allowing gas to escape during fermentation while preventing any from entering. In this CO2-rich environment, fermentation begins intracellularly by the action of enzymes rather than yeast or other microbes. The cherries may ferment this way for 72 hours before being moved to shade-covered drying beds, where they get dried as a natural-process coffee.
The Carbonic maceration process yields exotic, crazy, and unique flavors to the cup, such as bubble gum, red wine, whisky, and banana.
AQUAPULP COFFEE PROCESSING
Aqua pulping is the process of removing the freshly picked coffee cherry’s pulp and sticky mucilage through a mechanical demucilager machine. This machine scrubs the coffee cherry clean of any pulp or mucilage. It is also can leave levels of mucilage on the bean to produce honeys. In some origins, the aqua pulp process is replacing the traditional wet processing methods of removing the mucilage through fermentation and washing. It cuts the processing time and requires less water than the conventional washed process. In some coffee circles, people think that fermentation is necessary to produce a beneficial effect on flavor. Still, lately, many coffee producers and quality experts now accept the concept that mechanically washed coffee without fermentation can be of comparable quality to the fermented product.
Beyond dispute is that poorly conducted fermentation can cause disastrous losses in quality regardless of the process. Some of these methods have been quite successful, while others have been very susceptible. As the demand for exotic coffee continues to grow, there will be growth in experimental processing methods that will push the boundaries of what coffee can taste like. Regardless of their taste, these coffees are in demand, and these new processing methods are making their way into the market.
Many experts agree that, if they had to choose between the varietal, climate, or processing, processing would win out as most impactful to the final cup profile. Hopefully this has given you a good overview of the most common processes and some new ones. Next time you’re visiting your local roaster, give some differently processed coffees a try and see what’s up your alley!