Blog

The Next Step of Processing Coffee: Drying

An important step in the processing of coffee is the drying of the green beans. Once a coffee has had the fruity exterior removed and only the beans with the protective parchment layer remain, the moisture content of the coffee needs to be lowered to make them micro-biologically stable for shipping. Typically, the moisture content of a mature coffee cherry is somewhere between 50-70% but for coffee to be stable for shipping it must be between 9-12%. In this post we explore the different drying methods and what affect they might have on the final cup quality.

Patio drying

The most common method for drying coffees is patio drying. Green coffee is spread out over a large patio surface at a depth of around 2-3cm and dried under the sun. Drying times for washed coffees are around 6-7 days while a natural may need to be dried over 12-14 days. The coffee must be raked and turned frequently as it dries in the sun to ensure even drying and prevent any bacterial damage.

Raised African beds

In areas with rainfall occurring throughout the drying period, farmers will often use raised African beds. These are raised wooden frames with fine nylon mesh on which the coffee is placed for drying. The coffee is then raked and dried in much the same way as patio drying. The advantage of raised beds is that they allow air to circulate under the coffee and for water to drain away more easily. Raised beds generally result in more even drying and a better quality finished product.

Mechanical drying

The final drying method is mechanical drying. The coffee is put in to machines fuelled by gas or wood, which effectively work like tumble dryers, slowly drying out the coffee with temperatures not exceeding 42C whilst keeping the coffee in motion. Mechanical drying is often used in conjunction with traditional drying methods. For example; a farmer may place coffee on patios for two or three days to initiate drying and finish the coffee off in a mechanical dryer to allow for freshly picked coffee to go on the patios. While this method allows for farmers to get a return for their crop more quickly it may have the undesirable result of not drying the coffee out evenly and resulting high water activity levels.

The method chosen for drying the coffee is important as it can affect the quality and shelf life of a coffee. If a coffee is dried too quickly or unevenly the water activity levels within the coffee may be high. Water activity is the measure of how bound the water is within the coffee seed. If the water activity is too high it can result in green coffee fading and producing past crop flavours more quickly. As an example we sometimes will find a coffee which tastes exceptional as a pre-shipment sample but has lost its sparkle by the time the full shipment arrives.

Altitude and the Coffee Tasting Profile

The world’s greatest coffees are grown at high altitudes. But why is this?

A general rule of thumb is that the higher the elevation, the denser the bean and the more intense the flavours. The ideal coffee growing conditions are close to the Equator with abundant sunshine and at altitudes where the high elevation produces cooler temperatures during the night. This provides a slower growth cycle for the coffee tree which allows for a more complex development of the sugars in the bean, creating deeper, more interesting flavours. Better drainage at high elevations also reduces the amount of water in the fruit resulting in further concentration of flavours.

What’s more, as altitudes increase fewer insects are present to damage the coffee cherry. Arabica coffee trees are delicate plants vulnerable to pests. Interestingly, Robusta has twice the amount of caffeine as Arabica. Caffeine is a natural pesticide, making Robusta coffee much better suited for the harsher conditions at lower altitudes where insects thrive. Countries such as Hawaii, which grow their coffee at low altitudes around 2000ft- 3000ft produce less complex beans which tend to be fragile and can lose their personality quickly, especially if they’re not roasted properly.

The top coffee producers such as Colombia, Sulawesi, Papua New Guinea and most of East Africa typically grow their coffee’s above 5000 ft. This yields fruitier coffees with floral notes and a hint of spice, which explains all the complex flavours you can taste in your Handpicked coffee subscription.

Selecting Coffee Varieties

Conversations about coffee varieties usually begin with Typica or Bourbon. These were the first documented varieties and just about every major variety produced today will share lineage with either one, the exception being those cultivated directly from Ethiopian landraces. Typica and Bourbon are both varieties which produce excellent cup qualities but are susceptible to all major plant diseases and, in the case of of Typica, offer low yields.

For producers and governments alike it is important to be growing varieties which are suitable for the region and provide stable returns year on year. As such, many new varieties have been selectively bred and cultivated to strike the balance between high yielding, resistant crops and good cup quality potential.

Colombia: Caturra or Castillo

The best example of regional variety selection is in Colombia. Colombia is country which offers some of the best conditions for growing coffee in the world. It is also a region which has been devastated by leaf rust in years past.

Historically many farmers have grown Caturra, a compact, high yielding plant which produces very good cup quality. Caturra is highly susceptible to leaf rust and has carried with it a lot of risk for farmers that they may not produce a healthy crop. The Colombian government has sought to steer farmers away from producing Caturra and instead plant Castillo, a variety which offers much better leaf rust resistance but lower cup quality. 

This example highlights the balancing act farmers must consider. Do they risk the occurrence of leaf rust for the reward of higher cup quality and the corresponding higher prices? Or is it better to bank on a more consistent crop which may provide a stable year on year production even if the income return is lower? 

Throughout the coffee producing world trends emerge of varieties which are popular within certain regions. SL28 and SL34 are synonymous with Kenya, while you would expect to find Mundo Novo, Catuai or Acaia in Brazil. Gesha may never have become so famous if not for the careful curation and precise conditions found in Panama.

While certain varieties are expected within particular regions it is always exciting to see farmers experiment with new varieties. There is often some risk involved and typically farmers will only assign a small amount of their production to new varieties but the results can be game changing. This month’s coffee is an excellent example of just this. Java is a variety which has tolerance to leaf rust and coffee berry disease, medium yield potential and very good cup quality potential. We have found this coffee to be much more complex and interesting than the more common varieties grown throughout Nicaragua and we hope that the success of this crop leads to further production of this variety in the future.

How we roast our coffee

The primary goal of roasting is to represent each coffee in such a way that the roast itself is undetectable and the best qualities of the coffee are easily accessible to the drinker. Every coffee is inherently different based on its varietal, region, terroir and processing and as such will need to be approached in different ways. 

A good example of this is a Kenyan coffee compared to an Indian coffee. Kenyan coffees tend to grow at high altitude, in rich volcanic soils. The result is a very clean coffee with bright acidity and a lot of natural fruit-like sweetness. The beans are also very dense, so a typical roasting approach would be to roast the coffee fast and light. By applying a lot of heat and roasting it quickly the roaster is aiming to bring out the brightness of the coffee while allowing the natural sweetness to balance this acidity. The roaster needs to be careful not to damage the coffee with this fast, high heat approach, as this can introduce an ashy taste regardless of the level of the roast. 

By comparison, our recently featured coffee, India Bibi, was roasted a fraction darker and over a minute slower. This was because the beans were less dense and more likely to be damaged by roasting it too quickly. The Indian coffee also had a lower acidity and a heavier, more pronounced caramel sweetness. By roasting it slower we aimed to bring this sweetness to the forefront.

Coffee is generally not considered roasted until it has been through an event known as “first crack”. This happens when an evaporation layer within the internal structure of the bean cracks through the external shell producing a loud cracking noise. Until this point of the roast the coffee will still taste very “green” – vegetal, grassy and hay-like. At the point of first crack the coffee is undergoing numerous Maillard and caramelizing reactions contributing to the complexity, sweetness and body of the coffee. We generally aim to discharge the coffee sometime towards the middle of first crack when the coffee has been appropriately developed to no longer display any “green” tasting notes and yet not yet have any noticeable taint of roastiness from the roaster itself.

There is a further “second crack” which is an indication of the coffee is going through a phase of dry-distillation, essentially vaporising and separating various chemical compounds and introducing carbon-like tastes to the coffee. This roast can be identified through very dark, oily beans and is usually described as either a French or Italian roast. 

Roast colour, while a good indication, is not necessarily the most appropriate way to define a roast. There are many different ways in which a particular roast colour might be reached based upon the speed of the roast and how it has progressed throughout.

As you can see, many steps need to be completed with an almost scientific precision to achieve the perfect roast. But rest assured, your Handpicked coffee subscription is in good hands! 

Around the world – coffee growing regions

As an adventurous coffee subscription club, our aim is to curate an exploratory trip through the many coffee producing regions of the world. Coffee is grown within an equatorial band pretty much right around the globe. Each region produces unique characteristics based upon the terroir, micro-climate, common varieties used and regional processes. So where is coffee grown?

AFRICA

Coffee is native to Africa. Specifically the great rift valley in Ethiopia and South Sudan. These countries along with Kenya, Tanzania, Rwanda, Burundi, D.R. Congo, Malawi and Uganda are common stops for high quality specialty Arabica. East African coffees like these are typified by bright acidity and pronounced fruity and floral flavours. 

Coffee is also grown in West Africa but due to lower lying, tropical jungle-like conditions it is Coffea Canephora or Robusta which is most prominent here. There are pockets where Arabica can be found and we have tasted some great lots from Cameroon, watch this space.

SOUTH AMERICA

The powerhouse of the coffee producing world. Brazil alone produces over 40% of the world’s Arabica with Colombia coming in second at around 14%. Conditions in these two countries dictate global coffee prices by sheer weight of volume. If there is an abundant harvest in Brazil prices plummet for other much smaller producing countries, irrespective of their own harvest. 

Flavours range throughout the continent depending on altitude, processing and varieties. With the Andes being the backbone of coffee producing countries like Colombia, Peru, Bolivia and Ecuador – this altitude provides clean fruit-like acidity to otherwise chocolatey bases. While coffees from lower lying Brazil typically offer milk chocolate, nuts and a rich mouthfeel. 

CENTRAL AMERICA

The many different producing countries of Central America make up another key region for coffee growing. Honduras, Guatemala, Costa Rica, Nicaragua, Panama, El Salvador and Mexico typically produce well-structured coffees with balanced acidity. Each of these countries have contributed greatly to the development of better quality coffees. Whether it be innovations in processing methods or careful cultivation of new of obscure varieties.

Coffee is also grown in parts of the Caribbean such as Cuba, Jamaica, Haiti and the Dominican Republic. It also grown much farther afield in Hawaii where the famously expensive Hawaiian Kona coffees prevail. These prices however are more indicative of farming costs and scarcity than quality alone. 

 

What is specialty coffee?

We always talk about specialty coffee, but what does that actually mean? How is our coffee special and why is it worth waiting a month for that bag to come through your letterbox?

Technically, coffee can be classed as ‘specialty’ when it scores above 79/100 points using the grading system of the SCAA (Specialty Coffee Association of America). This looks at the main characteristics of the coffee including acidity, body, aftertaste, balance, flavour, aroma, fragrance. If we look at all of the coffee produced in the world, coffee scoring above 79 points is already in the top percentile, but there is a lot of debate these days about what ‘specialty coffee’ actually means, as the term usually refers to the world’s top-quality coffees. The best coffees sit between 84 and 90, and it is very rare that a coffee would score above 90. So our coffee subscription products are what you could call ‘top specialty’ or ‘gourmet specialty’. We go above and beyond specialty and buy coffee of at least 84 points, so a full 5 points above the minimum grade for what can be considered ‘specialty’.

These kind of coffees are the result of true dedication and extensive quality control, from the experts at origin to our 3 in-house Q Graders (the certification required to score coffee using the SCAA system). Every step of the coffee journey matters: it needs to be perfectly ripe when the cherry is picked, it has to be processed and dried correctly, shipped without any deterioration of quality, it has to be stored correctly and finally, it needs to be roasted to perfection, to bring out the best notes and flavours. We carefully make sure all of these steps are met so that the coffee that makes it into your cup is the best it can be.