The Curious Barista's Guide to Coffee

by Tristan Stephenson

  SPECIALITY COFFEE

  Speciality Coffee is a term that has been used since the mid-1970s to describe coffee of high quality and value that is in some way representative of its origin, variety or growing and processing practices. The speciality coffee model sees roasters negotiate the price of a coffee with a broker, importer, leadership representatives from a co-operative, or in some cases, the owner of a mill or a farm itself. Coffee is also sometimes sold at auction in the country of its origin, where roasters and importers bid for specific ‘lots’. The price paid for speciality coffee varies according to the C-price and its country of origin, but also, of course, according to its quality.

  Direct trade relationships between farm and roaster pursue better transparency and a fairer price for coffee.

  Certifications like those pictured guarantee some farming and trade standards, but have no bearing on coffee quality.

  Some roasters have, in recent years, begun building relationships with growers and in some cases dealing directly with them, known as a ‘Direct Trade’ relationship (see pages 34–35). The obvious benefits are that the farmer gets a fair price, the roaster has improved traceability of his product, and in some cases the ability to work with the farm on improving future seasons’ crops.

  ‘Relationship Coffee’ is another term that is sometimes used by speciality roasters. As with Direct Trade, the definition is slightly vague; neither of them are certifiable guarantees, and as such are subject to the possibility of being abused and misused. Relationship Coffee usually means that there is an ongoing dialogue between the roaster and the grower in an effort to improve coffee quality and traceability.

  ROASTING COFFEE

  03

  THE ROLE OF THE ROASTER

  We all know that roasting the coffee beans is an essential stage on the road to a mug of coffee. But its necessity aside, this keenly observed and succinct process that gracefully traverses the line between science and art, is nothing short of meteoric in its lasting effect on the character of the coffee. Decisions made at the roasting stage (as with most things in coffee) are irreversible, and it is for the home brewer, perhaps the most important stage of the entire chain of events that takes us from farm to cup. I know that’s a bold statement, and, practically speaking many of the cups of coffee you are served on the high street likely fall foul through no major fault of the roaster, but it would not be outrageous to suggest that the skill of the person who roasted the coffee that you are drinking right now has the larger part to play in the quality of the cup.

  And this, in a sense, is the quandary of the roaster. To better illustrate this, let’s compare coffee to wine for a moment. In wine production, the winemaker manages most, if not all, of the qualitycontrol points of the product, from growing, harvesting, juicing and fermenting through to filtering and bottling. The quality of the way it is served, however, is secured only by the consumer pouring the liquid at the appropriate temperature and finishing it within a sensible period of time. In coffee, on the other hand, the baton is carried on a frail and tenuous journey, each step accumulating the collective skill of all its previous keepers. The work of the first person and every person afterwards is all for nothing if the baton is dropped on the last leg, just as the tireless endeavours of a farmer in Nicaragua are wasted on a clueless barista.

  Any of the key people in the formation could claim that their reputation is in the hands of the other key players as, in normal circumstances, their powers only stretch as far as who they buy their product from, what they do with it once they have it, and who they sell it to. But it is the roaster who plays the most obvious middleman role between the beginning and end, and it’s the roaster that we, the consumer, best associate with. Folk will happily stroll into a random café safe in the knowledge that their favourite roaster supplies the coffee; while it may be naive to assume that the expertly roasted coffee from ’Roaster X’ will be prepared consistently by the hundreds of cafés that it supplies, not to mention the thousands of staff that the those cafes employ, it has become clear in recent years that the aftersales support and training that the roaster provides (along with the culling of those cafés that fail to uphold the necessary standard) is just as important as the product that gets loaded into its bags.

  THE SKILL OF THE ROASTER

  Roasters will buy coffee based on a number of factors; flavour is, of course, one of the most important, and this will in part be a reflection of how and when the coffee was picked, processed, graded, packaged and imported, and how these factors balance with price. Sustainability and ethics also play a part these days, so questions arise about how much a farm is being paid per pound of coffee, how sustainable the agricultural methods of the farm or estate is, and how the growers are being paid, if the coffee is the product of a co-operative effort from numerous smaller growers.

  This bag of Nicaraguan coffee clearly indicates the year of harvest, variety, farm and processing method (‘lavado’ translating as ‘washed’).

  Once the coffee is in hand, then it’s the skill of the roaster that shapes the final character of the coffee and connects the dots between origin, terroir and specific variety with those of brewing method and cup quality. But it’s important to remember that bad green coffee can be tamed, but not entirely saved, by the hands of a great roaster, just as a bad roaster – or an average roaster for that matter – can very easily corrupt even the finest speciality beans.

  Mastering the roast is an art form that can be likened to few others. The complex chemistry and physics of roasting coffee have been the subject of hundreds of books and research papers, as scientists attempt to identify the flavourful and aromatic constituents of good roasted coffee, and work out where they came from. Naturally, an understanding of the workings of the roaster itself is important, but an understanding of the green coffee and a clear vision of positive attributes that it harbours are also key.

  Piles of coffee beans at various degrees of roasting, from green (unroasted) at the bottom left to dark brown (French roast) at the top left.

  Those with their hands on the gas knob have adopted practices, tweaked their methods and tasted a lot of coffee in search of a better product. Today, our understanding of roasted coffee is better than it has ever been, but the growing realization that coffee is enormously complex has only really cemented a feeling of acceptance as to how powerless we are to truly affect and select its attributes on a molecular scale. Sure, through some trial and error and perhaps some referencing of past roasts, we might be able to highlight a peach-like acidity in Ethiopian Yirgacheffe coffee, or a chocolate character from Brazilian Daterra coffee, but hand-picking attributes with any level of precision is no easier than opening your fridge door and expecting a roast dinner to fall out.

  Part of coffee’s beauty is its ambiguity; it’s not roasted to an exact recipe of aldehydes, acids, sugars, carbonyls, caramels, carotenoids and other aromatic molecules in a perfect digital formula of saturation, contrast and brightness. Roasters are more like impressionist painters, where the artistry may be vague, imbalanced and imprecise, but the resulting composition as a whole can depict a richer, more emotional story through its imperfections.

  THE EVOLUTION OF THE COFFEE ROASTER

  The modern coffee roaster represents over 500 years of acquired knowledge. Improvements in design only became necessary once it had been established what was wrong with the equipment available at the time. A better design meant a better product, which would command a higher price for both the machine and the coffee it produced. Bigger designs were only needed once casual home roasters accepted that commercially roasted coffee was of a higher standard and more consistent than the stuff they were making on their fireplaces.

  Looking through the evolution of the roaster, there are three fundamental issues that the inventors have fought with. First is the even distribution of heat through the coffee bean mass, which we know gives a consistent and better-quality roast. Second is the speeding up of the process of loading and unloa
ding the roaster, which increases throughput (the rate of production or the rate at which something can be processed) and decreases labour cost. Third is the ability to monitor the roast by way of visual, or physical access to the coffee beans, which results in clearer precision and ultimately a better product.

  A 1774 engraving from Vienna shows coffee being roasted on an open brazier in the street.

  This Italian street scene from the early 20th century bears a striking similarity to the adjacent image.

  EARLY ROASTING

  We will probably never know exactly when the first coffee roasters came into existence, since they almost certainly evolved organically from the regular cooking equipment of the day. Stone bowls and clay cups were certainly popular options, left to sit over hot coals or an open fire, and occasionally stirred to ensure even bean browning. They got the job done, of course, but scorched bean surfaces and underdeveloped centres were commonplace.

  The first known dedicated coffee roaster made an appearance in Persia in the early 1400s. This roasting plate was like a large perforated spoon, designed to sit above an open fire pit or brazier and roast small quantities of coffee at a time; the holes in the plate tell us that early coffee drinkers recognized the importance of convection and good airflow in the roasting process. Similar designs followed, increasing in size and coming to resemble a large metal spider crouching over hot coals.

  The concave nature of the early roasting spoons also points to a general understanding of the importance of movement during roasting, to better aid even cooking. Further enhancements were made through the 16th century, culminating in Ottomaninspired long-handled frying pans, with sealed lids, and a long paddle – not dissimilar to a copper bedpan – that could be turned to agitate the beans.

  Cylindrical coffee roasters were the first major breakthrough. They came about in the mid-17th century and were probably of Turkish origin. Mounted over an open fire and generally constructed from tin plate or tin-coated copper, these roasters were sealed units, turned by hand, in efforts to keep the beans moving and, they believed, keep the aroma well contained. Whether recognized at the time, or not, these cylinders would have been a great improvement over the ‘open pan’ approach, through the uninterrupted shifting of the beans as well as the protection from open flames that they offered. By 1660, these cylindrical roasters were popping up in London, one example being Elford's white iron machine, which was ‘turned on a spit by a jack’ and considered a huge technological leap forward, since the use of human labour (usually in the form of a small boy) was no longer required.

  It was perhaps the Dutch who took the most serious approach to coffee roasting equipment, as attested by Humphrey Broadbent, ‘the London coffee man’ in 1722:

  ‘I hold it best to roast coffee berries in an iron vessel full of little holes, made to turn on a spit over a charcoal fire, keeping them continually turning, and sometimes shaking them that they do not burn, and when they are taken out of the vessel, spread ‘em on some tin or iron plate ‘till the vehemency of the heat is vanished; I would recommend to every family to roast their own coffee, for then they will be almost secure from having any damaged berries, or any art to increase the weight, which is very injurious to the drinkers of coffee. Most persons of distinction in Holland roast their own berries.’

  The Dutch-born ‘iron vessel’ that Broadbent refers to was the first wide-scale roasting solution for the household fireplace. Like Elford’s invention, it consisted of a closed cylindrical chamber of around 20 cm/8 inches in length, but featured a sliding door for the beans to be dropped through. The end of the roaster would be hung on the hook of the traditional fireplace crane and the wooden handle turned slowly to facilitate the roasting of the beans.

  This type of roaster subsequently evolved to become a free-standing contraption of larger proportions, also sporting a metal hood to help heat retention, more commonly used by coffee shops.

  THE EMERGENCE OF COMMERCIAL ROASTING

  Much of the coffee roasting that was taking place in Europe at the time was in the family home, in part because it wasn’t considered a skilled practice, and partly because it was an assurance of authenticity. Also, up until the end of the 18th century, roasters had pretty much all been small-scale pieces of kit, capable of processing no more than a few kilos of beans at a time. Home roasting was a slow means to an end, though, sometimes taking up to an hour, which yielded coffee that had a baked character, lacking in acidity and bite.

  But this was the era of innovation across all industries, from dairy farming and distilling to textiles and paper-making, with new technology successfully cutting back the required workforce and improving quality and throughput. Coffee roasting was no exception.

  The tentative first steps came in 1824, when Richard Evans patented the first large-scale commercial coffee roaster. Besides its size, the cylindrical roaster had a few added benefits over anything that had come before, including the facility to easily up-end the entire roaster to remove the beans from the roasting chamber. Evans’ design also designated a tube and ‘examiner’ that could be used to take samples from the roaster during roasting – a crucial step forward in the pursuit of quality.

  In the mid-19th century, quick unloading and reloading was an ongoing challenge that many inventors sought to provide a solution for, along with design modifications intended to help the roaster determine when the coffee was ready. One of the most innovative, yet slightly over-engineered solutions has to be Daussé’s scale roaster. Dating back to 1846, this French- designed piece worked on the principle that coffee loses around 15–20 per cent of its weight (mostly through water loss) during roasting. Beans were weighed before loading, then a target weight, relative to the desired degree of roast and the country of origin of the beans, was calculated. The roaster itself was suspended from a scale, balanced by a set of target weights on the reverse side, which caused the roaster to lift up during roasting once the calculated weight loss was achieved. It worked alright, but still required an arm to turn the drum.

  But as consumers placed greater faith in the convenience of ‘pre-roasted’ coffee, bigger roasters were needed, and who better to supersize a roaster than America? James W. Carter of Boston patented the design for his pull-out roaster in 1846, a system that became the commercial roaster of choice for the following two decades. The Carter roaster was basically a manually turned sheet-iron drum, about the size of a large wine barrel, that was fixed into a brick coal furnace. It had one major difference, though: loading and unloading of the coffee was performed by ejecting the whole drum from the furnace and opening a door on the side. Before doing this, a bucket of water would be tossed into the roaster to kick-start the cooling, then the roasted coffee was ejected and promptly raked across the floor, filling the room with steam. In this way, the furnace itself maintained its heat and batches could be run through faster.

  Entire banks (or batteries) of Carter roasters were installed in the largest coffee roasting companies of the time – such as the Dwinell-Wright Company of Boston.

  A battery of Carter roasters at the Dwinell- Wright roastery in Boston.

  THE EMERGENCE OF THE MODERN DRUM ROASTER

  The undisputed father of the modern commercial coffee roaster is surely the London-born, but subsequently New-York-based, Jabez Burns. The Burns roasters of the 1860s and 1870s sported two major improvements over previous designs, both of which can be identified in contemporary drum roasters. The first was a series of flanges placed on the inside of the roasting drum – essentially a modified Archimedes-screw design – once confusingly described by Burns as ‘a double right and left augur, one within the other, firmly secured together and also to the shell or cylinder’. The screw continuously directed the flow of coffee beans back and forward through the length of the drum, achieving even heat distribution throughout the bean mass and scoring bonus points for easy unloading of the roasted coffee without the need to remove the drum.

  Burns’ second innovation was in the field
of postroast cooling, in which he was one of the pioneers. In an 1867 design, he pioneered a method of drawing cool air through a bed of roasted coffee, speeding up the cooling-down process, and no-doubt improving the quality of the product. Modern drum roasters have cooling trays that work under the same principles.

  There were explorations into different fuels during this time, too. Early industrial roasters were heated with coal, coke or peat, which in many instances would have almost certainly contributed a smoky taste to the coffee, and in the case of coal, possibly imparted carcinogens into the coffee. Natural gas was a welcome arrival when it began hitting European and American cities in the mid-19th century, since it was both smokeless and far easier to control. Most commercial roaster manufacturers switched over to manufacturing gas models from the 1880s onwards, but there were still coal-powered models being released well into the 20th century.

  Spherical roasters, like large iron globes, which aimed to better distribute heat, had a brief spell of popularity at the turn of the century, but these designs soon lost favour over the easier-to-operate drum. By the early part of the 20th century, the template for the modern roaster had been more or less set in stone, exemplified by the likes of Probat’s ‘Perfekt’ roaster, released in 1907, with its electrically powered drum on a horizontal axis, a gas heat source and a cyclone set-up to assist in cooling the roasted beans and removing chaff.

  Further advances, far-reaching in their effect but comparatively small in their alteration to the basic design, have been welcomed by roasteries through the 20th century. The development of the double drum and indirect firing are perhaps the two most significant in terms of improving coffee quality. Both of these technologies have increased the speed, consistency and precision of roasting, the first by reducing scorching of the bean surface and the second by reducing the temperature of the roast while at the same time increasing the rate at which heat is applied. Control systems on modern roasters have reached a state of sophistication today that not only allows complete control over temperature, airflow, recirculation of air, drum rotation, cooling mechanisms and after-burn, but also the computerized profiling of such things, completely tailored to the requirements of the bean.