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Rob Butterworth, of Butterworth and Son in Bury St Edmunds, explains the factors that determine the different flavours of coffee

Whilst chatting recently, I was posed the question: What makes coffee taste different? Why does coffee from Colombia taste different to coffee from Kenya?

Aside from the way a roaster may roast coffee, factors in the growing and processing play a large part. The mineral content of the soil that enriches the plant and the altitude at which the plant grows – the higher altitude plots being favoured for their more bountiful crop and complex flavours.

There are two main varieties of coffee plant, Arabica and Robusta. Arabica plants are known in general for more complex flavours only growing at higher altitude and Robusta being suited to lower altitudes but providing coffee with body and a higher caffeine content. Higher altitude plots are often harder to farm, being on steeper slopes and inaccessible by good roads due to the nature of the terrain. This in turn can impact the price somewhat.

Coffe beans drying (34631687)
Coffe beans drying (34631687)

Progressing into the Arabica family of coffee trees, there are many varietals or ‘types’ of tree, and like apple varieties produce fruit of different taste. Coffee originated in Ethiopia and many original heirloom varieties still grow here with my preferred region, Yirgacheffe, offering floral notes and being lighter and brighter, think citric flavours.

Well-known varieties popular in Central and South America are Bourbons, Caturras, Catuai and Typicas. Different varieties have different attributes – crop yield, cup flavours, disease resistance. There are more than 100 coffee varieties and hybrids play a part, too.

Taking into consideration good farm management and harvesting, the coffee cherries, once picked from the trees, then go to processing to ultimately have the beans (bean if a Peaberry) removed from the skin, pulp and mucilage. Four main processing types impact the flavours at this point:

Fully washed – the picked cherries go through a washing method whereby the skin and pulp around the bean are removed. Once the cherries have been through this method they are dried, commonly on large concrete patios where weather permits. This process softens the vibrant notes and some acidity of the coffee producing subtle yet consistent flavours. It’s the most popular process for coffee production but uses vast amounts of water, which is a precious commodity in the parts of the world where coffee is grown.

Pulped natural – cherries are pressure washed to remove the skin and pulp. Provides consistent but bland flavour, commonly used in Brazil for coffees that are blended and sold commercially.

Honey – this process has become very popular recently. Coffee cherries are spun in a centrifuge (like a honeycomb) to remove the skin and some pulp, then left to dry. This method is somewhere inbetween dry/natural processing and fully washed and produces intensely sweet coffees without the sometimes overpowering notes of fruit that are produced from the natural process.

Natural/dry – Very popular in Ethiopia where water is in short supply, and the heirloom varietals seem to suit this processing style. Coffee cherries are left to dry on raised beds for 8-12 weeks. Produces lots of fruit flavours in the cup and, in some respects, too many for the uninitiated. The cherries do not come into contact with water at any point during processing.

All of the above processes have variants and slightly different techniques. Dry milling to remove the parchment which remains from all of these processes is a very standard process and occurs after any of these processes.

Rob owns Butterworth & Son coffee roasters and tea smiths, based on Moreton Hall, and Guat’s Up! café in Guildhall Street.

His job takes him around the world visiting coffee farms to source great coffees.

See butterworthandson.co.uk/guatsup.coffee