The smooth, sweet and syrupy elixir that we know as espresso is actually the end result of a long and complex journey from crop to cup. There are two main species of coffee tree – Arabica and Robusta. Arabica is grown in higher altitude regions and makes up about 70% of the worlds production, while the under-rated Robusta is more commonly used as a booster for some espresso blends or for making instant coffee. It is the cherries from these trees that provide the stepping off point for our journey.
When the cherries are ripe (ie; a deep red colour, soft and fleshy), they are harvested – usually by hand – and then sorted to ensure unripe or poor quality cherries are discarded. After harvesting there are a number of steps that need to occur before the bean is ready for grinding. The first is ‘processing’ – where the outer layers of the cherry (the skin and the flesh) are removed. The way that these outer layers are removed greatly affects the flavour of the bean as the sugars can be either transferred into or out of the bean. There are two main processing methods – dry processing and wet processing. Dry processing is the more traditional method where the cherries are dried in the sun on platform beds or, alternatively, in mechanical driers. This process intensifies the sugars in the bean which adds to its body and flavour. For this reason, dry processed beans are more commonly used for espresso.
In all, there are four layers that need to be removed – the skin (a thick red or burgundy layer), the flesh (a soft, fleshy layer similar to that of a grape), the parchment (a hard husk that protects the bean) and the silverskin (the flaky outer layer of the bean which is usually removed when the coffee expands during the final roasting process). After processing, the beans are dried and stored in their parchment ready for shipping.
The next determinant of flavour, aroma, and body is the blending of different origins and the method of roasting. An expert Master Roaster will take into account the country of origin, the locality of the individual farm and the method of processing to determine the roast profile that will most successfully extract the full flavour of the bean. This is both a science and an art and the next leg on the journey of the bean.