I recently went to a high end café in Sydney’s CBD and ordered an espresso. I asked the person behind the counter whether they had a single origin on offer and was told that they did indeed and that the coffee’s origin was Nicaragua. I went on to ask whether the coffee was washed… at this point the person behind the counter sniffed, glared at me, and spat out “All of our coffees are washed…” Of course I wasn’t checking on the café’s sanitation and hygiene procedures. I was asking about the process by which the flesh of the coffee berry had been removed to allow access to the coffee bean, which is actually the seed of the coffee berry. I was asking about this process, because the process itself has a large impact on the flavour of the roasted coffee.
The first fork in the road of coffee processing is whether the fruit is pulped or not. If the fruit is not pulped then the only option for the coffee farmer is referred to as the natural process whereby coffees are patio sun-dried with their skin on. If the fruit is pulped then there are two main processes used: washed-process and pulped natural process. A pulping machine is used to release the coffee beans from the fruit and calibration of the machine can help to separate green unripe cherries from ripe cherries. By regulating the pressure of the pulping machinery appropriately only the ripe fruit will break open and release beans which pass through screens which are designed such that only the beans can proceed. Unbroken green cherries move to the end of the system and can be separated from the ripe coffee beans. Coffee beans that have been pulped remain covered in a slippery substance known as mucilage. If dried on patios then this is referred to as pulped natural or honey process. If sent to fermentation tanks then this is referred to as washed process. Finally the coffee is dried from 60% moisture to 11-12% moisture commencing on large concrete patios and then moving to mechanical dryers.
Why this level of detail on coffee processing? The natural process produces coffee that is viscous, sweet, smooth and with highly complex fruit and ferment characteristics. For me, the most enjoyable natural process flavour/aroma, most evident in coffee from Ethiopia, is that of blueberry or even blueberry muffin. Washed process coffee results in coffee which is clean, bright and fruity. The process is extremely good at preserving the acidity of the coffee bean and is used in countries with naturally high rainfall. I love washed Kenyan coffees! Pulped natural coffees display the characteristics of both natural and washed process coffees. They can be sweeter than washed coffees, have much of the body of natural process coffee, and also echo the characteristic acidity of washed coffee. Brazil is the most famous user of this type of processing.
Next week we’ll continue this discussion on coffee processing and explore some of the newer and more technically intensive methods of processing coffee cherries to access coffee beans.
