Not just wet work — coffee processing made simple

Have you ever wondered what coffee has to do with washing? Or what links a beehive with a cup of black coffee? If so, you have probably encountered the mysterious terms washed, honey or natural on a packet of Colombian coffee. In the coffee world, these describe processing methods: the second stage of work on a farm after harvesting. Although wet, natural and honey processing might not sound like an exciting first-date topic, we hope they will charm you as much as they charmed us.

Processing the fruit, known as coffee cherries, strongly influences the finished coffee's flavour. How long the seed — the future coffee bean — remains in contact with the aromatic fruit, and how much of its character it absorbs, helps determine acidity, complexity, balance and flavour notes. How can processing develop the desired aroma? Without experimenting, growers can choose one of the most established traditional methods.

Tradition first

Washed, natural and honey are three of the best-known processing techniques, long familiar in the coffee world. How do they differ?

Natural

Natural processing means patiently waiting for harvested cherries to dry in the sun before separating the fruit from the beans. It is extremely time-consuming: even in hot, dry equatorial African countries, reaching the required moisture content of around 11% can take three to six weeks. Yet the time spent enclosed in pulp and skin is precious. This is when the bean gains sweetness and the full aromatic character nurtured throughout cultivation.

What else do we appreciate about it? Its relatively low environmental impact. By processing naturally, countries such as Ethiopia and Yemen avoid drawing heavily on already scarce water resources.

Washed

Washed coffee uses water during processing, allowing the fruit to be separated from the seed more quickly. It is therefore a very widely used method on modern farms. After harvest, cherries pass through a depulper, which mechanically removes the pulp. The beans then spend anything from a dozen to several dozen hours in fermentation tanks. Repeated rinsing and control of water temperature and bean condition allow growers to influence the complexity of the bouquet and pH — in other words, the coffee's flavour.

Honey

The word “honey” captures the beans' appearance during processing. After mechanical removal of the skin, they undergo natural fermentation with a coating of fruit mucilage, resembling sticky pieces of honeycomb. Particularly popular in Costa Rica, this method is a compromise between the previous two and can create a complex, intriguing bouquet.

Specialists vary fermentation conditions by working outdoors or in special tents that limit airflow. Different approaches produce the distinctive styles known as yellow, red, golden, black and white honey.

Alternative techniques — coffee from the laboratory

As in every world of flavour, for every traditionalist there are enthusiasts of progress and experimentation. Modern technology has inspired innovative processing methods that bring new and intriguing aromas into the cup. If you love coffee discoveries, try beans subjected to anaerobic fermentation, or those that, much like wine, absorb fruit character in a sealed container filled with carbon dioxide.

To feel like a scientist in your own coffee laboratory, experiment with a stylish Chemex, highlighting the notes developed in each bean.

Local and distinctive

If neither tradition nor technology defines your taste, explore a third group: unique local processing methods used for centuries in small communities worldwide. There is Indonesia's wet hulling, known as giling basah, which produces coffees with remarkable tobacco and herbal notes in Sumatra's persistently humid conditions. Or consider Indian monsooning, exposing beans to powerful monsoon winds for three months.

These are just some of the local techniques you can discover as you delve deeper into processing. How can you taste the differences between washed, honey and anaerobically processed coffees? Brew them in drippers or an AeroPress, which help reveal complex bouquets and rich aromas.