IT STARTS WITH NATURE
The coffee flavours we enjoy, however we chose to drink it, doesn't start with the Barista, or even the coffee roaster. Its fundamental essence comes from nature: the ground, the farm or estate and country of origin in which the plant is grown. At this basic stage, the location where they are grown, altitude, rainfall, soil composition, farming practices and species of plant are the major contributors in what we palate in the end.
There are approximately 8000 species of coffee. Only four species account for what we use in the trade. The two main ones are coffea arabica (Arabica) and coffea canephora (Robusta), with another two lesser commercially used species being coffea liberica and coffea excelsa.
Arabica in general palates with more desirable flavours, from sweet to a citrus tart. It grows better in higher altitudes where the temperature sits at about 15 to 25 degrees with healthy rainfall. It does unfortunately yield smaller amount of crop, and has less caffeine and is more susceptible to disease.
Robusta however has more caffeine, crop production is at higher levels, is more resistant to disease, can grow at lower altitudes and can survive hotter temperatures. It does however have a more prominent/harsh or sharper taste than Arabica, which is why Coffee roaster blenders sometimes prefer adding a percentage of Robusta to increase a cups lasting flavour and body.
Single Origins is the term used to break down the country of origin that the coffee beans have been grown. The more boutique roasteries and cafes go as so far as to catagorise their blends and origins further into bean types and specific regional estates in which their green bean supply have come from. Each Single origin accompanies its own profile, so many roasters sometimes prefer showcasing a particular estates offering untouched by other flavour influences.
The Coffee Bean Belt is the name given to best describe the area of the latitudes between the Tropics of Cancer and Capricorn in which all coffee plants are grown. This "belt" contains the most suitable climate in which coffee plants grow more effectively for yielding premium cultivation quantities.
Blending comes in handy when you want to create a unique flavour or offer a more complex palate profile in a coffee cup. The objective of blending is the carefully selected percent mix of various bean origins for each bean to add its own characteristic where another origin might fall short. This process is a cumbersome task, as the roaster must have advanced knowledge of the bean origin cupping profiles and how they react to different roast levels and how they compliment other beans too.
Cupping is one of the most integral and highly specialised parts of the roasting process that will ensure that the roaster recognises and evaluates particular qualities in single origins and blending that can aid a strict quality control and consistency of final product.
Cupping allows for the isolated evaluation of fragrance, aroma, flavour, acidity, body, and aftertaste attributes.
Coffee roasting is the level playing field of art and science. The roaster's skill is to create their own expression of their character using coffee, that will embody a flavour that people can enjoy, much like a food chef creates signature dishes. Each roaster has their own style and how they perceive coffee should palate. This is why they choose the coffee origins or estates, blend them the way they do, roast the beans to the level they envisage that will create that roasted bean that a barista will revel in to use and the drinker will gladly wait in line for a cup.
To achieve this ultimate goal, a roaster must also understand the science of what happens to the green bean during its time tumbling through the drum roaster. Roasting is fundamentally the heat process that turns green coffee beans into the rich brown beans we see at the grinder and espresso machine. When achieving the desired roast result, the beans are promptly released onto a cooling screen to stop the roasting process.
Roast-masters use sound, sight and smell to determine when the beans are roasted to perfection. Timing is everything. First, the green beans are dropped in the roaster at a temperature above 205°C (400f). They are constantly rotated inside the drum to achieve a consistent roast. Most roasters use a combination of bean mass, temperature, smells, color, and sound to monitor the roasting process. Initially, the process is endothermic (absorbing heat). Then at around 175 °C (347 °F) the roasting becomes exothermic (giving off heat). For a roaster, this connotes that the beans are heating themselves at this time a roaster usually makes adjustments to the roaster's heat source. From First Crack, the beans are inspected every few seconds until the Roaster sees the they are the desired colour, size, surface texture and smokiness depending on the level of roast we’re creating.
Sound is one of the indicators of bean temperature that a roaster observes during roasting. There are two temperature benchmarks called "cracks" that roasters listen for. At about 200–202 °C (392–396 °F), beans will emit an almost popcorn cracking sound. This point is called the "first crack," marking the beginning of light roasts. As roasting continues and the beans are at about 224–226 °C (435–439 °F), they emit a "second crack." These two phases mark the point where pressure inside the bean has increased to the moment where the structure of the bean fractures, rapidly releasing gases. Along with a roasters skilled visual and olfactic observation, decisions can be made on desired roasting.
Start with green coffee beans that can be stored for up to two years.
Drying Phase -165 °C (329 °F)
The beans are undergoing endothermic heat until their moisture content has evaporated, giving off a wet grass smell until "first crack".
Cinnamon Roast - 196 °C (385 °F)
Immediately at first crack beans are light brown, with toasted grain smell and flavors with sharp acidity, almost tea-like in character.
New England Roast - 205 °C (401 °F)
Visually light brown, but beans still "wrinkly" in appearance. Some specialty roasters prefer this level to highlight bean origin characteristics that keeps a beans complex acidity.
American Roast - 210 °C (410 °F)
Medium brown in colour, developed during first crack with beans having a non-oily surface. Origin character is still completely preserved.
City Roast - 219 °C (426 °F)
Visually rich brown colour subjectively selected by some roasters for specialty coffee retaining the varietal character of a bean with hints of roast character becoming more noticeable.
Full City Roast - 225 °C (437 °F)
Visually medium dark brown in colour with some noticeable oil sheen on the surface with roast character palate profile becoming prominent. This stage of roasting marks the beginning of the "second crack".
Vienna Roast - 230 °C (446 °F)
Visually moderate dark brown with light surface oil and audibly in the middle of second crack this lends the coffee to be complex bittersweet caramel flavour with its acidity has been nulled. Any origin characteristics have become eclipsed by roast at this level.
French Roast - 240 °C (464 °F)
Visually dark brown in colour and shiny from oils breaking through to the surface, it palates with pronounced burnt bitterness, and non-existent acidity. The roast phase is past the end of second crack. No traces of the aroma or flavors of the coffee are noticeable with a deep roast character being prominent.
Italian Roast - 245 °C (473 °F)
Visually very dark brown and shiny, burnt tones are dominant with very little body.
Spanish Roast - 250 °C (482 °F)
Pretty much black and extremely oily, charcoal and tar tones dominate, flat, with a very thin body. If you have ever wandered what Obsidian would taste like, or fantasized about tasting the ash from the belly of a volcano...this is it!!!!!
Once a roaster has observed and decided what level of roast they want to achieve, their split second timing will guide them to release the roasted beans onto the cooling tray that rushes cool air through the hot beans as to promptly cool the beans and stop heat from further roasting the beans beyond the desired level.
What is De-gassing.
The coffee roasting process causes a series of physical and chemical changes that create the wide range of aromas and flavours in the coffee.
Roasted beans give off carbon dioxide over a period of weeks, (one kilogram of coffee can produce up to six litres of gas), but approximately 40% is given off in the first 24 hours. If the beans are ground, brewed and drunk immediately, then some of this CO2 would dissolve in the water and give a true acrid taste due to an even stronger degassing from the cell destruction and enlarged surface area. It is important for a roaster to allow for degassing to occur as the flavours on some beans seem to develop over a period of 2 to 3 days. Thus beans should be left to degas for a day or two before distribution for use. Fresh coffee is not bad immediately, but beans just improve with their aroma and flavours if allowed to de-gas.
After the period of de-gassing, beans should be stored in a dry and cool place. Staleness is mostly caused by continuing internal chemical changes and predominantly by oxygen getting to the bean. Moisture absorption from the atmosphere, air allowing coffee aroma to dissipate and temperature fluctuations, accelerate the coffee oils breakdown, ultimately making the coffee rancid. Probably the best method is to put them in one-way valve bags as to let the CO2 out but prevent the oxygen coming in or there are Jars on the market that you can buy that have built in vacuum hand pumps to suck out the air. It is also handy to also use Mason jars (glass bottling jars) which can be ideal if you are a regular buyer of smaller fresh quantities of roasted beans from your local quality local specialty roaster.