Guide to Post-Harvest Processing for Coffee
Coffee growing and trade support the economies of many countries that produce coffee. Such countries like Kenya, Ethiopia, Brazil and Guatemala, to name a few, are largely dependent upon this commodity for their export earnings, and thus for the continuation of their development program in the social and economic fields. Historically all coffee-growing countries fall into the lower-income and middle-income nations of the world in terms of annual average GNP per capita. At least 20 coffee producing countries are classified as least developed countries (LDCs) (Mutua 2000).
Coffee is grown and exported by more than 50 developing countries, but the major consumers are all industrialised countries, The United States of America, Europe and, more recently, Japan. Globally, coffee is the second major traded commodity to oil and thus plays a vital role in the balance of trade between developed and developing countries, providing the latter with important source of export earnings to pay for imports of capital and consumer goods. Coffee growing and its related activities provide a major source of employment in all producing countries. The International Coffee Organisation (ICO) has estimated that coffee growing provides direct full-time employment for 25 million people worldwide. Taking into account related industrial and service activities (processing, marketing, roasting, and transportation) the figure rises to 100 million people, including families.
Specialty coffee is a segment of the overall coffee market that buys premium coffees that score 80 points or higher on a 100 point scale. The coffees are graded at origin in a cupping. Specialty Coffee is the fastest growing market for coffee in the US jumping in growth from 1% to 20% of total market share in the last 25 years(SCAA 2014), and it is guided by the Specialty Coffee Association of America (SCAA). Third Wave Coffee depends on the SCAA standards for quality of coffee and pricing, and aims for transparency surrounding their beans all the way down to the exact producer and process method.
Post-Harvest Processing for coffee refers to generally 2 steps- first you must process the cherries in order to remove the fruit from the bean, and there are several ways to do this, then you need to mill the bean to remove the parchment surrounding the bean. If you are a fan of Third Wave, then you have come across the three different post-harvest processing methods for coffee. Here’s a guide to what they mean and how different processing methods can affect flavor.
image via Perc Coffee
Guide to Post-Harvest Processing
- NATURAL (Dry): It is the oldest method of processing coffee where the fruit is spread out on patios or raised tables and allowed to dry in the sun. The main requirement is reliable sunshine, so the regions that use this method are reliable sunny, think Ethiopia and Brazil. The coffee is turned regularly to avoid mold, fermentation, and rot. The fruit dries around the seeds, forming a raisin-like husk that is then removed mechanically through a dry mill. These coffees typically display a muted acidity, pronounced fruit notes, and a rounded body. This process imparts a lot of flavor to the cup, but lower quality naturals can be a little funky.
image via Crema Coffee
• HYBRIDS (Honey, Pulped-Natural, Semi-Washed): The fruit is run through a mill, removing the seed’s skin and pulp. Coffee cherries are ousted by using a depulper or the more-expensive mechanical de-mucilager, which can be customized to remove only the cherry and very little mucilage, which will come into play here in a second. The beans are then allowed to dry with varying portions of a membrane called “mucilage” intact.
After the cherry's departure, the beans go directly to the sun bathing station, where they are slathered instead with their own mucilage. In the washed process, the beans would be dunked in the fermentation tank and washed at this point. The drying process is delicate, though, requiring constant attention to ensure evenness and avoid too much fermentation and rot. During this stage, akin to the natural process, the mucilage is drying into the bean, and creating the desired flavor profile. This process reduces acidity and increases body, while also infusing the coffee with an undeniable sweetness.
The honey process has several degrees ranging most mucilage to least. They are: black honey, red honey, yellow honey. These terms and meanings differ from mill to mill. The result is coffee with a sweet and juicy body, gentle fruit notes, and a nice balanced acidity.
image via Crema Coffee
• WASHED (Wet): This method is more resource and equipment intensive. It was invented in Central America in the 1800s. The fruit of the coffee plant (cherry pulp) is completely removed by using a depulper. The depulper splits the coffee cherry with sharp blades, separating the bean from the cherry. Removing the cherry reveals a thin layer of mucilage on the bean. This sticky mucilage is composed of sugars and alcohols, which contribute to the coffee's sweetness and acidity. Mucilage is removed from beans by using fermentation tanks. In the fermentation tanks, the mucilage is eaten away by bacteria and microbes, before being washed off with water. Mechanical demucilagers scrub away the coffee's mucilage with bristles--what's left after the scrubbing is still washed away with water, but this mechanical process uses much less water overall. After emerging from the fermentation tanks or the demucilagers, the beans are dried. Before being shipped, the beans will be hulled at the dry mill, removing the parchment. This preparation results in brighter coffee with a crisp, structured acidity and a silky body. Washed coffees present cups that are true representations of origin, but require more resources and investment like equipment and water.
image via Crema Coffee
Coming into Specialty coffee from a chocolate background, I expected coffee to go through a fermentation like tea, so when I learned that various methods include fermentation and other do not, I was surprised. I expect fermentation to alter the taste of the food being fermented but with coffees this is not the case. The fermentation is used as a natural and less-intensive way to remove the fruit from the cherry. When cacao goes through its fermentation, the bean changes from inedible to edible, but coffee remains true to its own flavor. This could be because the fermentation is allowed to occur individually with each cherry, where with cacao you throw all the beans along with their mucilage into a batch and cover them to start an anaerobic reaction. I wonder what would happen to coffee if it went through a fermentation like Cacao!
I will leave you with a coffee processing video from my fatherland. I hope this guide is useful for understanding the delicious coffee available to you nowadays. Happy watching!
Signing off
-Anjuli