Roasting is truly an art. Depending upon the place of origin, each coffee bean will react differently to the heat generated during the roasting process. Since coffee is produced in about 80 countries, different growing conditions causes each countries coffee to roast and tastes differently and different roasting styles achieve different flavor profiles.
As a general rule, the longer the beans are roasted, the darker the final color of the bean.
It is critical that during the roasting process the beans are not under or over roasted. Under roasting results in a coffee that has an undeveloped flavor, while over roasting produces a coffee whose flavor may taste acidic or burnt.
The principle of roasting coffee is a simple two step process
- Most coffee roasters are cylindrical machines that operate like a clothes dryer.
- Raw green beans are roasted at temperatures between 380 and 480 degrees Fahrenheit.
By revolving around in the cylinder of the roaster, the beans are allowed to roast uniformly. The intense heat produced during the roasting process triggers complex chemical reactions within the green bean. This causes the bean to pop and nearly double in size losing moisture.
As moisture is drawn from inside the green beans and evaporated, the sugars and starches are transformed into oils. It is these oils that give coffee its flavor and aroma. As the coffee roasts, and goes through these changes the Roaster uses these changes to monitor the coffee and keep it roasting at the correct rate.
After the beans have reached the desired level of roast, the roaster discharges the coffee into a cooling tray. The cooling tray has a powerful fan that draws cool air through and around the beans causing them to cool evenly.
Decisions about how quickly and how darkly to roast are in the hands of the roast master, thus the excellent flavor depends upon the roast master’s skill and experience.
There are several types of generally accepted roast profiles that are used in the coffee roasting process. Roasts are generally described as:
- American Roast – a chestnut brown colored bean with a caramel like flavor.
- Vienna Roast – a dark brown with a minimal amount of oil on the bean’s surface and a definitive dark roast flavor.
- French Roast – a very dark brown bean with large amounts of surface oil. The flavor of the bean is bitter and has a very distinctive aroma.
- Italian Roast – a bean that is almost jet-black with large amounts of oil on the bean’s surface. This roast has a flavor that is very acidic and almost burnt taste.
- Cinnamon Roast – a light brown almost cinnamon-colored bean that has a nutty flavor profile.
- Full City Roast – a dark brown bean with no visible traces of oil and represents the purest taste of coffee, combining the flavors of caramel, chocolate, and dark roast.
Table of Contents
Finding the Best Roast for the Coffee
There’s much to consider in such an endeavor, and while it can seem we’re largely nerdy Machine Operators using our knowledge of coffee to pretend we’re worldly and hip, most Roasters I know have an uncanny hunger for recognizing the finer points of coffees by origins and grades.
Then they further that obsession at the helm of the roasting drum, would-be alchemists that we are, to hit a religious balance of all things tasty and memorable. Determining the sweet spot in a roast can come down to so many factors.
The Green Coffee
Green coffee is what arrives to a Roaster’s shop. Depending on the time and energy spent sampling coffees from different importers, the coffee can have varying degrees of defects, moisture levels, density, and sizes. All of which impact the action during the roast.
Using the cupping process, we figure out quite a bit about its potential and weigh these things to decipher a profile.
Cold beans change a roast. Rain and sun can change a roast. Barometric pressure can change a roast. Relative humidity can affect one’s roast. Wind can mess with one’s airflow.
Weather is uncontrollable, relative to this discussion. Roasters have formulas, ideas, trials and errors that make up a host of responses to all these factors. In time a Roaster figures out that correct response to most situations to get the good stuff out of the coffee consistently.
The Roasting Machine
The roaster (machine) one uses makes a world of difference as well. No two roasters are exactly alike. The Roaster (capital “R” is a person, lower case “r” is a machine) gets up close and personal with their machine and knows it inside and out and develops all the little tricks that make it perform just as it should. It’s like training a horse to ride or something like that. Care, love, stubbornness and trust are required.
Profiling Coffee Roasts
Profiling is what happens during the roast, and in what ratio of time and temperature it occurs. If you graph a coffee roast, with time measured out horizontally and temperature vertically, you see a nice little curve when you plot out the process.
A good Roaster has some version of this data in their mind at all times in the process — combined with smelling, listening for 1st and sometimes 2nd “cracks” in the roast when beans temporarily become exothermic (emit heat rather than take in) and thinking ahead about the application of heat with combinations of fire and/or airflow.
The profile is likely the most essential element to a Roaster’s philosophy. The better of us can’t get enough of trying to unlock everything that happens here. We learn pieces of physics, chemistry, meteorology, engineering, agronomy and anything we can. We have knowledge of the thermodynamics of heat transfer (although we don’t mention this at parties, because it quickly clears a room right after eyes start to glaze over).
Profiling also entails the nuances and styles that you might most recognize. Namely the roast level, or darkness of the roast, is part of the profile. The movement these days is in full support of getting the absolute best from the coffee itself, imparting very little, if any, hints of carbony, roasty flavor characteristics that might hide the floral aromatics or fruity acidity from a drinker.
However, roast philosophies and traditionally-styled roasts like French and Italian roasts come into play often and ensure consumers a wide range of roasty- flavored coffees as well.
Profiling slightly darker can also help smooth out espressos, take funkiness or bite off of some coffees and longer, slower roasts near the end of a batch can build up a bit of body in a coffee where it was otherwise lacking. Whereas a quick, lighter roast can save sweetness and acidity in some coffee while leaving others tasting too green and underdeveloped.
Profiling is the tricks and treats of roasting coffee, and I encourage everyone to try out different roasts with a mind wide open to all the tastes they can muster to really understand the potential of truly great coffee.
No roasting happens without coffee farmers, pickers, millers, exporters and importers, dock workers and the whole gamut of the globalized economy. Still most coffee earns people who handle it pennies a pound. All other passions aside, this is why coffee needs to be the best for us.
The value we impart can prove critical to the benefit of countless others down the chain. As a Roaster I see this as the most important motivation and logic behind learning more and dealing in coffee up to my eyeballs everyday. Without that recognition, coffee and its people are just another commodity.
It is All in the Taste
Much of a coffee’s taste and characteristics can be attributed to the region where it is grown. Coffee identified by its growing region is called a varietal. If two or more varietals are combined we call the resulting mixture a blend. Even if you have never tried a coffee before, you can learn a lot about it based upon its origin. Although there are many different varietals from all over the world, coffee can be broken down into three major geographic families.
African: Coffees from this continent are generally bright and winey,with a sparkling acidity and a medium to full bodies.
Indonesian/Pacific: These coffees are often smooth tasting or “earthy” in flavor, exotic, low in acidity and full-bodied.
The Americas: These coffees are all grown in Latin and South America with the exception of Kona, which is the only coffee grown in North America. They have clean, crisp taste, with high acidity.
Common Terms to Describe Coffee Flavor
Bitter: A harsh, unpleasant taste detected on the back of the tongue. Coffee that has been over-extracted or over-roasted is often bitter.
Blend: A mixture of two or more individual varietals of coffee.
Bland: Neutral in flavor.
Earthy: Spicy, “of the earth taste”, mostly found in Indonesian coffees.
Flat: A dull, lifeless quality due to lack of acidity.
Fruity: A flavor taint that is said to come from over-ripe, fruit-pulp.
Light: Used to describe aroma, acidity, or body.
Mellow: A full, well balanced, satisfying coffee. Implies low or medium acidity.
Nutty: A specific flavor nuance suggesting almonds or other nuts. Can also be used to describe a coffee with a lack of flavor.
Sour: Not to be confused with
acidity. A distinctively sour, rank, or
rancid taste is a defect often due to improper processing.
Spicy: A fine aroma or flavor that hints of particular spices.
Winey: A flavor reminiscent of fine red wine. Kenya coffee is one of the most notable.
Key Tasting Terms
Acidity: Coffees with high acidity have a sharp, pleasing quality that highlights the flavor and creates a lively cup. Acidity can be high, medium, low or lacking altogether in coffees, in which case the coffee tastes flat or dull.
Aroma: The fragrance of brewed coffee. It can be lacking, faint, delicate, moderate, strong, or fragrant (also called aromatic).
Body: The impression of weight and texture in the mouth. Coffees can be watery, thin, slight, light, medium, full, heavy, thick, or even syrupy in body. Some textures include oily, buttery, rich, smooth, and chewy. Body also varies
with the brewing process, i.e. French Press coffee has a much heavier body than drip coffee.
Flavor: The total impression of a coffee described with terms such as aroma, acidity, and body.
General Flavor Characteristics
Balance: The satisfying presence of all the basic taste characteristics where no one characteristic overpowers another.
Complexity: The perception of multiple flavors.
Rich: Indicates deep and complex flavor and a full body.