Coffee Processing

Coffee Processing

You might have seen the words ‘washed’, ‘natural’, or even ‘honey’ processed on our coffee bags and wondered, what’s that all about? Processing the coffee cherry after it’s been picked is not only fundamental in producing a coffee seed (bean) that can be roasted; the differences in processing can radically alter the flavour of the coffee.

Whilst washed coffees are generally cleaner and medium bodied, natural coffees can be intensely sweet with more ‘funky’ flavours like tropical fruit. 

Here at the roastery, we love a crisp washed Guatemalan just as much as a floral natural Ethiopian, and want to share the exciting ways processing impacts flavour and body in your cup of coffee.

Washed processing

When you drink a washed coffee, you’re mainly tasting the inherent favour of the coffee bean. This is because the process completely removes all the layers of the coffee cherry (skin, fruit and mucilage) before drying, unlike natural or honey processes which utilize the outer fruit to impact flavour. 

If the end cup of coffee is going to be delicious, it’s vital the bean has gained sufficient natural sugars and nutrients during its growth. This means the varietal of the coffee plant, and environment in which it’s grown really come into play, as well as ripeness (deciding at what point to pick the coffee).

After the harvest, the coffee cherry is put through a de-pulper that removes the skin and fruit. Next the mucilage is removed by fermenting the beans in tanks, typically between 12-36 hours. Finally, the bean is washed with clean water and dried on raised beds or patios. These steps will help determine if the coffee bean’s true flavour really shines through.

Natural processing

Natural processing dries the coffee cherries with the fruit and mucilage left intact, which means the flavours in the outer layers begin to ferment and merge with the bean. Although this process requires less investment (and water) than washed processing, it depends heavily on climate. Ethiopian coffee, where access to water can be harder but the climate enables efficient drying, is well suited to natural processing.

After harvest, the coffee cherries are sorted for ripeness and then dried in their full form (usually on patios or raised beds). There is some risk involved as the cherries need regular turning to facilitate even drying, whilst avoiding over-fermentation and the development of molds. When the coffee reaches an agreed moisture level, its outer layers are removed in one step by a de-pulper or hulling machine.

The result, as well as intense sweetness, can be more fermented, even boozy, flavours in the cup. Whilst some aren’t fans of these funkier tasting notes, others love the complexity natural processing can showcase. At Wood St we believe well processed naturals can be hugely exciting – have you tried our Birbissa yet?

Other processes

Honey, or pulped natural processing, sits somewhere between washed and natural. The coffee is not placed in fermentation tanks after de-pulping, so it’s dried with the sticky mucilage still intact. Producers can experiment with how much mucilage is left on, and for how long, as this affects the final flavour of the coffee. 

Experimentation in processing is certainly growing; playing around with the fermentation stage, washing the coffee using different temperatures, even freezing the cherries straight after picking. It takes a lot of research and investment, but can produce incredible results. 

We’re always keen to sample new processes at the roastery, and love sharing the broad spectrum of flavours coffee processing creates. Our brew pack always includes at least two different processes, if you’re interested in brewing and tasting the differences at home.