Preventative measures include pesticides, but as with fungicides used against coffee leaf rust, there are associated costs and protocols that must be followed, along with environmental considerations. Traps are the most common means of dealing with the borer. Usually homemade, they may comprise a large red container (posing as a giant coffee cherry) with an ethanol solution lure inside it. An even better solution is to let another bug do the work for you… say hello to Karnyothrips flavipes, a type of thrip that is one of the only known natural predators of the coffee weevil. It’s early days, but there’s evidence to suggest that increasing the thrip population in weevil territory might be effective in keeping the parasite in check.
PROCESSING COFFEE
The way a coffee is processed before shipping sets the precedent for the style of coffee that will eventually leave the roaster. This stage of the coffee bean’s life is sometimes referred to as ‘wet milling’ and encompasses all the various steps that occur from when the coffee is picked, right up until it is ‘dry milled’ and loaded into bags for transportation. Processing practices vary considerably from between regions and farms, sometimes because it is simply ‘the way it’s done’ and other times on account of the limitations of economy or resources. In some circumstances, like in Burundi, farmers hand over their picked cherries to one of the 150 government-operated washing stations, called sogestals, for further processing. In other countries, on other farms, all of the processing is done by the farmer. This seemingly routine stage in the development of the coffee is far from inconsequential, however, because the effectiveness of these local interpretations open up new expressions of flavour in the coffee bean, bringing distinction to the coffee’s natural profile in a way that is specific to each farm or processing facility.
Screening is usually conducted in a water tank where overripe fruit and very underripe fruit (along with leaves and sticks) will float. The ripe and underripe fruit sinks to the bottom and is then piped out ready for the next stage. However, irrespective of how meticulously the coffee has been harvested, underripe and overripe cherries are more or less inevitable. Excessively over-, or underripe fruit will, like any other fruit, result in a bad-tasting product – this is not something that a good roaster can cover up. Fruit that is perhaps only slightly underripe or overripe may meet the minimum requirements of the exporter and roaster, but cup quality will ultimately suffer, as it is the perfectly ripe fruit that contains the most sucrose, and results in the sweeter cup.
Be it the finest speciality coffee known to man, or the most deplorable coffee fruit destined for jars of instant, one way or another the coffee beans need to be removed from their fruity shell and cleaned of their slimy cherry mucilage. This is usually done in one of two ways: by wet (or washed) processing or natural (dry) processing. Some countries or regions prefer to use one method over the other, and others process using a combination of both techniques, which is known as pulped-natural or semi-washed.
Mechanized harvesting on one of Brazil’s enormous coffee plantations.
NATURAL COFFEE
Naturally processed coffee is a relatively straightforward process, as all its various layers are left intact. The fruit is sent to the patio or a raised drying bed for drying and, where relevant, ripening. This process can take many weeks and care must be taken to avoid mould and rot, but some natural fermentation is normal. After the fruit has fully dried, its dark, shrivelled form must then be hulled (peeled) to reveal the beans patiently waiting inside. Brazil is the spiritual home of naturally processed coffee, where the economic culture of coffee has bred a ‘pick now, sort later’ approach, with the likes of São Paolo State and the Cerrado region naturally processing over 90 per cent of their coffee.
Naturally processed coffee is non-interventional, self-contained and, well, natural, which gives the resulting coffee its dirty, heavy and wild – often to the point of wacky – fruit notes. The capricious brilliance of dry processed coffee can yield inconsistent results, however, and the clarity of the cup can be lost. It is for this reason that some roasters choose to avoid it all together. But what it lost in finesse can be made up in body and density, which is why naturals often play important supporting roles in some of the world’s best espresso blends.
WASHED COFFEE
Washed coffee, also known as wet-processed coffee, sees the whole cherry get pulped, either mechanically (by what is effectively a large blender) or by jets of high-pressure water. Either way, the cherry is split and squeezed, forcing the beans though a separate aperture. If you really wanted to, you could pulp cherries by hand, but from personal experience I can tell you that it is slow, messy and thankless.
Pulping only deals with the soft flesh of the cherry – there’s still the mucilage that coats the bean to contend with, and like the last slimy bits you get on a peach stone, it turns out it’s highly resilient stuff. The tenacity of mucilage is attributed mostly to its combination of sugars and pectin, the latter of which acts both as a binding agent that is common in many fruits, and also as the gelling agent used to thicken marmalades and preserves.
Removal of the mucilage is ordinarily done by way of fermentation, which in fact refers to a broader process of microbial growth rather than the action of yeast and sugar in the absence of oxygen (as is the case with brewing). During its time spent in fermentation tanks, the pectin in the mucilage is broken down through the activity of enzymes, and the environment becomes more acidic. The length of fermentation depends on a number of factors, not least of which is temperature and the volume of coffee being processed. Experience and a good feel of the seeds will tell you when the operation has run its course. Fermentation is not just about removing mucilage, though; it’s also an exercise in coffee flavour development, and, when timed well, it can produce a level of clean acidity that natural coffee can only dream of. After some washing to remove any excess mucilage, the beans are sent for drying on raised beds, or concrete floors, for around a week.
Despite the positive reputation that wet processing possesses, it is no assurance of quality. Fermentation can be unpredictable, particularly since it relies solely on micro-organisms that are naturally present on the fruit and/or in the water. Defective beans are not uncommon and most infamous of all is the ‘stinker’, a bean that produces a particularly unpleasant taste; this can easily damage many kilograms of roasted coffee if they are permitted to pass along the production chain.
A classic hand-operated coffee pulper in Mexico works by splitting the cherries and separating the skin and flesh from the beans.
Wet-processed coffee sees the pulping of the coffee fruit prior to washing.
There are, of course, numerous variations of wet processing specific to different countries and regions, too. In Kenya, for example, it is common for two fermentations to take place, with an intermediate wash in the middle; this has been cited as one of the reasons for Kenya’s incredibly bright and fruity coffees.
For farmers, the decision to dry or wet process is mostly one of economics – wet-processed coffee is widely recognized as a superior product, but it requires huge quantities of water, numerous tanks, decent plumbing and other pieces of specialist equipment. Incidentally, it’s also for this reason that most robusta coffee is processed naturally, because there’s little point in wasting resources on improving a fundamentally inferior product.
PULPED NATURAL COFFEE
Pulped natural coffees are recognized under a variety of other titles, including ‘semi-washed’, ‘semi-lavado’, and the delightful-sounding ‘honey-processed’. These terms don’t necessarily describe identical processing methods, as with the regional differences in their names, there are differences in their methodology too – but they are all in effect a combination of natural and wet processing. For a coffee farm, this marriage of methods neatly combines the economic benefits of the natural process with some of the speed of the washed process. In the resulting cup of coffee, you tend to find better body than some washed coffees, but more clean and crisp c
haracter than with natural processing.
The process starts out in the same way as wet processing: the coffee is first pulped to remove the skin and flesh. As with washed coffee, the mucilage remains attached to the seed, but instead of being sent to fermenting tanks for removal, the beans skip straight to the drying phase. Drying pulped natural coffee is particularly challenging, as the moist and sticky environment is the perfect setting for rot and decay. Mechanical dryers don’t work, as the mucilage sticks to the hot surfaces like glue, so the coffee is dried on raised beds or raked over large patios in a process that takes one to two weeks.
During pulping, the farm can also choose to remove some, or most, of the mucilage from the seed before drying, which speeds things up even more. It also gives the green bean a lighter colour, and takes the character of the coffee further in the direction of a washed coffee. Mechanical demucilagers are becoming more commonplace and are effectively an extension of the pulper, whereby they depulp and strip the mucilage through the use of rough bristles or through the use of water pressure. Critics of these types of machines claim that foregoing the fermentation process of a fully washed coffee denies the coffee some of its clarity and acidity. Interestingly, in response to this criticism, some growers are choosing to scrub and partially ferment their coffees.
Seeing as the amount of mucilage left on the seed is so important to the final character of the coffee – steering it in the direction of washed or natural character traits – this scrubbing or ‘shaving’ process is now loosely graded in the context of honey-processed coffee. ‘Black honey’ retains most of the mucilage before drying; ‘red honey’ removes some; and ‘yellow honey’ removes all, or nearly all of it. You can get a good idea of the extent of scrubbing simply by examining a sample of beans, where the actual colour of the beans vaguely corresponds to the style of honey processing.
Costa Rica is a good example of a country that has embraced this kind of processing with gusto. Many farmers there are investing in small demucilagers to fine-tune their processing methods. This becomes particularly interesting when a single estate releases a crop that has been processed in two or more ways, because it allows us humble consumers to draw taste comparisons between the different methods.
This natural coffee has completed the long drying process and the dried fruit has formed a protective husk or shell.
DRYING
Whether undergoing wet processing, the pulped natural or natural method, eventually the coffee must experience a drying process that reduces the moisture content of the bean from 40 per cent down to around 10–12 per cent. This is a process that requires constant attention, since the warm, moist piles of beans need to be regularly turned to avoid the development of mould and bacteria. Airflow, temperature, humidity and light must all be taken into account.
Patios are the oldest, cheapest and simplest form of coffee drying, where the coffee is spread a couple of inches deep and raked hourly to provide equal airflow and light to all the beans. One of the useful traits of the patio is its ability to soak up the heat during the day, which it continues to release overnight, thus providing quite stable and consistent drying conditions.
Raised beds, also known as African drying beds, are becoming increasingly popular around the world. Constructed from wood and thin mesh screens, they look a lot like very long silk screens, or hammocks, that sit at waist height. The advantage of the bed is the improved airflow that it offers, meaning that the coffee does not need to be turned as regularly. Some beds, in countries such as Colombia – where the weather is changeable – also have plastic covers (like a poly-tunnel) that protect the coffee from rain, but still allow sufficient airflow. In Nicaragua and Sumatra, in Indonesia, it is common to see coffee dried on tarpaulin – a very low-cost solution.
Some hot countries, specifically those in Africa, have been forced to develop multi-stage drying processes that aim to limit the effect of the midday sun. These include such practices as moving the coffee from shade to light and piling it in mounds to moderate the evaporation of water. The general consensus is that the best coffee is produced when the rate of drying decreases near the end of the process.
As you might expect, there are also more industrial means of drying coffee, but these are not as commonplace as one might think. Once again it boils down to economics, where the cost of a mechanical dryer simply cannot compare with the price of cheap labour and a little bit of time. However, there is no escaping the fact that mechanical dryers at their best offer a much more consistent product, especially in areas of unpredictable weather, in a fraction of the time – usually taking just 12–24 hours from start to finish.
After drying, the coffee bean is still encased in its brittle parchment shell and will remain a relatively stable product, protected from external flavours and susceptible only to the dangers of extreme temperature and moisture. Beans are usually rested at this stage, for at least a few weeks, but only up to three months. This strengthens the cell structure of the bean and prolongs its shelf life following the dry-milling phase.
One exception to this rule can be found in Indonesia, where coffee is hulled of its parchment layer while still wet. After the coffee cherry is pulped, a brief fermentation period occurs, followed by a single wash. Then the coffee is dried for a short time and hulled of its parchment while still wet. With the premature green bean now fully exposed to the world, it is dried to the usual 10–12 per cent, sans-parchment, resulting in a coffee that is heavy and earthy in character – typifying the Sumatran style.
LEFTOVERS
Perhaps you’re wondering what happens to all discarded coffee fruit? The coffee bean itself accounts for only around 20 per cent of the wet weight of the whole coffee cherry, so there is quite a lot of waste. In some countries, the wet pulp is recycled as fertilizer, but disposal of the vast quantities of waste water that are used in this process, and the subsequent pollution caused by coffee cherry mucilage are problems that are consistent all over the world.
Some producers have taken to drying the cherry flesh into a product called cascara. Resembling a dried cranberry, cascara can be brewed into a kind of fruit tea that tastes a little like high-octane rosehip tea, due to the caffeine present in the fruit.
Workers on this estate in Ethiopia’s Yirgacheffe region dry their washed coffee on raised screens, also known as African drying beds.
MILLING AND TRANSPORTATION
To complete its journey, the coffee must be dry-milled to remove the parchment, then graded for quality, checked for defects, sampled, packed, and exported. Who, exactly, the farmer sells to in any given scenario will be based on a number of factors including – but not limited to – the size of the producer’s farming operation and its financial circumstances, the degree to which the producer processes the coffee, customs in the area, geographical limitations, presence of co-operatives and the legal structure within the country.
Most growers, however, sell ‘parchment’ coffee (dried beans that are still encased in their endocarp, or parchment layer, while still in this form, the coffee is a mixed bag of large and small green beans, cracked beans, twigs, leaves and probably a bunch of other things besides. Since it still requires milling, screening, grading and repacking (and as much as 30 per cent of a bag won’t make the cut), parchment coffee is worth a lot less than prepared green beans. Growers sell their product either to a dry mill, which does the job of removing the parchment and sorting the coffee, an exporter (responsible for shipping the coffee) or a middleman, or even two middlemen (known colloquially as coyotes); often, these guys will hang out at bus stops and collect bags of parchment coffee from small farms, pay for them, then transport them to the mill or the exporter for sale. It’s also worth noting that some dry mills export the product themselves, and some exporters operate their own dry mills.
Some growers rest, mill and sort their coffee before selling to exporters, but that is quite rare outside of the biggest farms. There are even some growers who handle their own export, too, but
this is even more scarce, and not without its headaches from an importer/roaster’s perspective. Some large Brazilian estates dry-mill their coffee but leave the sorting up to the exporter; this ungraded type of green coffee is called bica corrida there. The term translates as ‘spout race’, describing the practice of quickly milling and packaging the green coffee.
In some countries, there may also be a co-operative in the mix, often representing over 1,000 small growers. Co-operatives will sometimes do the job of wet milling (see page 30) and drying the coffee beans; some will also take charge of storage, before shifting the parchment coffee on to an exporter, while others may have dry-milling facilities and indeed, perform the role of the exporter.
Between every link in the supply chain, there is the possibility of a trader or broker dipping in, too. Traders can buy up stocks of coffee, add it to their inventory, then sell it on to the next man for an increased price. Brokers basically do the same thing but without ever taking physical possession of the coffee; they are in effect just connecting sellers with buyers and skimming their cut off the top. When you put it like that, it makes the role of the trader and broker seem dispassionate and hard-nosed, and that can sometimes be the case, but in many scenarios it is the hard work done by these individuals that connects the best coffee with the speciality market.
Even the best pickers make mistakes. This fruit will require sorting before it can be processed.
The Curious Barista's Guide to Coffee Page 4
