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By: Holly Kragiopoulos 03 February 2015
We are often asked about the different processes used at origin as part of coffees journey from seed to cup, so we have decided to produce a short series of blog posts dedicated to explaining the differences between processes and the effect each have on the cup profile.
Coffee processing embodies all the stages involved from the moment a cherry has been picked (either by hand or machine) to the moment it is finally dry milled and sorted ready for shipment. Methods of coffee processing vary from farm to farm, region to region and country to country with differences in picking, pulping method, fermentation time, water quality and availability, speed of drying etc. We are constantly developing our understanding of these variations but in an attempt to make sense of them all, it is possible to separate processing into three main categories: Washed, Honey (Pulped Natural) and Natural.
In this first part of ‘Coffee Processing Explained’, we have decided to cover off the initial harvesting of coffee cherries and how that may vary between different origins.
Structure of a Coffee Cherry
First of all, to understand the different stages in processing, we feel it is important to be clear on the structure of a coffee cherry. There are usually two coffee beans which sit facing each other inside the cherry. These are encased by a ‘silver skin’ within a ‘parchment layer’ inside the coffee cherry which is then surrounded by sticky pulp (also known as mucilage). A ‘Peaberry’ is a natural genetic mutation which results in just one seed being fertilised that occupies the whole cherry, forming a smaller round bean. The idea behind all variations of coffee processing is to end up with the final product, which is just the bean encased in its silver skin. It is only when it has reached this stage that a coffee bean is ready to be roasted.
Stage 1 – Picking
Every process whether it be washed, honey or natural must begin with the picking of the coffee cherries – though it is only for speciality grade coffee that it is imperative these cherries are picked when ripe. Depending on the varietal, cherries can mature with red, yellow or orange colour – for example, you can have red, yellow or orange Bourbon. Ensuring that the cherries are ripe is a critical stage involved in picking as it can greatly affect the quality of the finished product. Even if there is just a small percentage of unripe cherries in a lot, it can result in a slightly sour/underdeveloped flavour in the coffee. The growers we work with are awarded quality premiums for the extra effort involved in selecting only the ripe cherries.
In every producing country, other than Brazil, coffee picking is an arduous task carried out by hand and often on tricky terrain. On larger farms or estates, a team of pickers are hired during the harvest season to pass all the trees, picking the ripe cherries as they go. It will often take up to 7 passes of the farm to harvest the cherries as different parts of a tree ripen at different times. On smallholdings, the picking is usually completed by family members who then deliver the ripe cherry to a local wet mill.
In Brazil, due to the flat lay of the land, cherries are picked using picking machines which gently shake the trees and suck up the cherries. This is very efficient and means Brazilian farms can be run with a surprisingly small number of staff given their size and yield which is often why Brazilian coffees are slightly cheaper due to these lower costs in production.
…Stay tuned for Part 2 where we will discuss Natural Processing