Coffee Process
Coffee is a processed food.
Before any coffee can be roasted and consumed, it goes through a processing method that converts it from a fruit to a dry green bean.
That green bean is actually a seed that grows inside a cherry, to get that seed out of the cherry, the fruit surrounding the seed has to be removed.
Each coffee cherry is made up of several layers: the outer skin (pulp) or exocarp; the mucilage or mesocarp, a silky, sticky layer that’s responsible for much of the coffee’s sweetness; a papery layer or endocarp called parchment; and the silverskin, a membrane which covers the two seeds
There are several different methods to process coffee. Some methods are very common such as Washing (or Wet-Process) and other methods are specific to origins like Wet-Hulling, or Giling Basah in Indonesia.
Each method imparts characteristics that affect the flavor of the coffee.
A NOTE ON COFFEE PROCESSING
At its simplest, coffee processing is intuitive, with producers monitoring weather conditions and moving coffee between patios, raised beds, covered solar dryers, and mechanical dryers until the beans reach the desired level of humidity. At its most complex, processing involves hourly record keeping of metrics like temperature and pH, custom built tanks with valves and gauges, and constant adjustments to keep everything on track.
Natural Process
Also called the Dry Method, Dry Process, Unwashed and Natural Sundried
The original method.
The natural process, also known as the dry process, is a back-to-basics approach that stems from Ethiopia. The fruit is left on the bean, and there’s little disruption to the coffee while it dries. Although it needs less investment, it still requires certain climatic conditions to ensure the drying of the fruit and seed in time.
To prevent the cherries from spoiling, they are raked and turned throughout the day and then covered at night or during rain storms. This process, which can take 3-6 weeks normally, is the more-traditional method of processing coffee. This process of drying the cherries out in the sun originated in places without reliable access to water and usually works best in areas with low humidity and infrequent rain — such as parts of Ethiopia and Yemen — although we do have some farmers using the natural process in other places.
If consistency can be achieved, then many argue that natural coffees can match washed coffees for clarity, and also provide some more interesting notes and characteristics as well. You can see this happening in Brazil, among other places.
After the cherries have been dried to the optimum level, they are sent to mills to separate the seeds from the rest of the dried fruit, otherwise known as being “hulled.”
Washed Process
Also called the Wet-Method
One of the most common coffee process methods.
KEY TAKEAWAYS
Focus: Typically, washing allows for a better expression of the intrinsic character of the bean, as well as the “terroir”.
Profile: Very common to have a “clean” and “bright” or “sparkling” acidity, and a strong fruit quality (all of the sugary mucilage has been removed form the cherry).
Benefits: Greater consistency of cup profile
Concerns: One of the biggest criticisms of washed processing is its high water usage. Not only is this an issue in places with water shortages, but poor disposal of the wastewater can result in chemicals entering local waterways. This has led coffee associations and equipment manufacturers to invest in finding ways to achieve the effect of washed processing without the environmental cost.
1. Sorting
After the coffee cherries are picked, the producer will begin sorting them (this removes any defective or unripe cherries). Interestingly, higher quality coffees are denser than water, while poor quality cherries have more air and will float to the top. Those that rise to the top get separated then processed and sold separately.
2. Pulping
After the cherries are sorted then the skin fo the cherry needs to be removed. A machine called a depulper is often used (coffee is sometimes run through a sieve to make sure that all the skin is in fact removed).
3. Fermentation
The fermentation step involves removing the sticky mucilage of the cherry that surrounds the seed, and then submerging the seed in water where the remaining flesh is removed.
Fermentation (typically) can take anywhere from 18 to 24 hours, depending on the temperature. During this time, the microorganisms in the beans create the enzymes responsible for breaking down the mucilage. After fermentation the seeds are washed again with water before drying.
4. Drying
The final stage of the washing process is when the exposed seeds of the cherry are laid out to be dried. There are several ways to dry the seeds; traditionally coffee is laid out in the sun and watched very closely, some producers choose to use mechanical drying methods. Either way it’s very crucial that drying is managed with extraordinary care – the exposed beans is vulnerable to microorganisms as well as deterioration.
Honey Process
Also called Yellow Honey, Red Honey & Black Honey Process
A little bit natural and a little bit washed — but a whole lotta different.
KEY TAKEAWAYS
Focus: Drying the bean with the fruit of the mucilage takes advantage of the fermentation of the pectin and sugars to impart a unique flavor.
Profile: Honey process can give the bean a fuller, more rounded body and muted acidity. The mucilage of the cherry is naturally sweet. The sticky texture and the golden amber color are what give the process its namesake; it looks and feels like honey (but often honeys can have a honey taste).
Benefits: Less dependency on water for the final drying phase. Producers can slow down or speed up the fermentation creating a new taste profile.
Honey processing became popular in Costa Rica in 2008 after a massive earthquake struck the country and caused water shortages. Previously, most coffee mills in Costa Rica had used the washed-process method, which produces clean and bright flavors, but is water-intensive.
Generally, lighter color honeys indicate faster drying times and less fermentation, while darker colors indicate longer drying times and therefore more fermentation.
White Honey
White Honey Process coffee is fermented for the least amount of time. It is typically dried out in the open sun, where it is flipped often to keep a cap on enzymatic and bacterial activity. Shortly after drying, the mucilage is washed away and the coffee bean is dried for export.
Yellow Honey
The beans are turned often, even as much as hourly and they dry more quickly and evenly. This helps minimize any negative effects of over fermentation. Yellow honeys are great for pour-overs and drip brewing methods.
Red Honey
Red Honey processed coffees spend between two and three weeks drying. Within such a long time-frame, there are often overcast days and sunny days, so the natural variation in weather will slow or speed fermentation accordingly.
Black Honey
To get to a black honey stage the mucilage turns almost entirely black. Block honeys can be turned as little as one time a day. This process is expensive and time consuming — the craft it takes to perpetrate the stasis for the fermentation to be stretched out over a long time without negatively effecting the beans, is considerable. With the extended drying time more bacteria and yeast development that helps break down the pectins and residuals sugars into acids and alcohols which combine to produce flavor compounds. Without constant attention, the coffee can turn sour, moldy, and over-fermented. Great for espressos,
Giling Basah
Also called Wet-Hulled Processing
A very local (mostly Indonesian) process.
Giling Basah is a term used by Indonesian coffee processors to describe the method they use to remove the hulls of coffee beans. Literally translated from Indonesian, the term means "wet grinding".
Most small-scale farmers in Sumatra, Sulawesi, Flores and Papua use the Giling Basah process. The mature coffee fruit, referred to as the coffee cherry, is harvested. and farmers remove the outer skin mechanically using locally built pulping machines. The coffee beans, coated with mucilage, are stored for up to a day during which a natural fermentation breaks down the sticky residue. Afterwards the coffee beans, protected by a parchment hull (endocarp) are washed off before being let out to dry.
Contrary to other traditional drying methods, where the parchment coffee is dried until it reaches about 12% moisture content, the beans in the Giling Basah process are hulled when they reach between 30 and 35% moisture content; still semi-wet. The green coffee beans are then further dried to reach the exportable 12% moisture content. This operation gives the beans a unique bluish-green appearance and is thought to reduce the acidity and increase the body, resulting in the classic Indonesian cup profile.
The Giling Basah process can create a "goat's foot," a split on one end, in green coffee beans. Sometimes the hulling machine partially crushes a soft bean, giving the bean a shape resembling a cloven hoof.
Monsoon Process
Also called Monsoon Malabar
The origins of Monsoon Malabar date back to the times of the British Raj.
Monsoon process is a rather old-fashioned processing technique that doesn’t get much love from the specialty coffee community. However, once in a while you still see this particular bean show up in an espresso blend.
The process take its name from the Malabar coast in India. Back in the days, it took months to ship coffee from India and back to Europe. During that time the beans would get exposed to all kinds of weather, among them the monsoon, and somehow they developed a unique flavor. As naval transportation improved, the trip suddenly became a lot shorter, and the customers complained that the coffee lacked the old ‘monsoon’ flavor. A new processing method was invented that aimed to replicate the conditions of the arduous journey from east to west.
Whole crops of cherry coffee are selected and sun-dried in expansive barbecues. The dried beans are cured and sorted into 'AA' and 'A' grades, after which they are stored in warehouses until the onset of monsoon. From June through September, the selected beans are exposed to moisture-laden monsoon winds in well-ventilated warehouses (12 to 16 weeks time). The monsooning process involves careful handling, repeated spreading, raking and turning around in regular intervals. The beans absorb moisture and get significantly larger, turning a pale golden color. Further micro-sorting is done to separate fully monsooned beans.
Processing Innovation
Anaroebic Process
Anaerobic (oxygen-free) fermentation is a new method where the coffee is processed in a fully sealed and oxygen deprived fermentation tank. First, the cherries are de-pulped and separated from their mucilage. Then, the seeds are added to a ferment tank and covered with their own tightly-packed mucilage gel. After around 18-24 hours, the anaerobic process has caused a breakdown in the mucilage and a huge buildup of CO2 pressure in the tank. This pressure forces the flavors of the juicy mucilage into the coffee parchment. Once carefully removed from the tank, the coffee is dried to ensuring a halting of the fermentation stage. This experimental process yields unexpected and complex flavors, while also giving the producer great control over the sugars, temperature, pressure, pH and length of the ferment.
Kenyan Processing
Kenyan coffees are famed worldwide due to their high acidity, clean flavors and unique notes of apple, blackberry and tomato. Part of this is down to the unique Kenyan coffee varietals SL28 and SL32, but another reason is the special almost all coffees are processed in this country.
The Kenyan method is often called the double fermentation. The beans are first soaked for 12 to 46 hours to remove any pulping residue. Then they are washed and rinsed off. But then they are put in a second fermentation tank, where the process repeats itself for 12-24 hours – this time with significantly less sugar. Again, a wash and soaking follows.
Carbonic Maceration
This processing method emerged in Costa Rica around 15 years ago. However, the traditional Brazilian way of processing coffee bears many similarities. The process starts with the coffee cherries being harvested and washed. Once they’re washed, they’re sealed in a stainless steel container that gets carbon dioxide pumped in to remove all of the oxygen from the sealed container. Once the oxygen is out, the coffee beans will sit in water that is carefully monitored for temperature. These stainless steel containers are then put into greenhouses where the temperature is kept around 24 degrees celsius. This process allows the beans to macerate in a carefully controlled environment to ensure that the finished product has a very distinct flavor. It also makes it easier to duplicate the same flavors over and over again.
Acetic & Lactic Processing
The innovative Colombian Farm, ‘La Palma y El Tucan’ has created two different signature processing methods called ‘acetic’ and ‘lactic’ processing. Both are variations of the traditional Colombian wash process, but with some key differences. The pulped beans are fermenting in special anaerobic tanks, where the oxygen flow and pH level can be controlled. This promotes the growth of certain strains of bacteria that will create either lactic or acetic acid. After the fermentation the coffee is dried in two stages. First on drying beds and afterwards in a mechanical dryer.