By Sherri Johns

Roasting sounds simple enough. Buy green coffee beans. Buy a coffee roaster, put the two together, and crank up the heat, set a timer, take a break and out comes a batch of roasted beans fit for a king, right?
Not so: roasting is a skilled craft that requires constant evaluation and evolution.
Probably the first challenge is the learning curve of tasting, locating and securing quality green beans.

Importers can help you. Other resources that identify the world’s best coffees include the Cup of Excellence and web sites like Coffee Review by Ken Davids (www.coffeereview.com) and www.sweetmarias.com - and certainly reading this trade journal is a big step in the right direction.

A taste of place
Learning cupping skills, a process to evaluate good, excellent, average to poor qualities of a coffee prior to buying. This sensory analysis is as important as buying the roaster itself.
Once you develop a palate you can determine which beans to buy and move forward. Secure the beans then determine at which point of roast the coffee tastes best. The exact degree of roast a coffee needs to have to insure its flavors will be presented as you desired. Sumatra may stand up to a darker roast due to the size of the beans and density whereas the winy brightness a Kenya offers will give way to char once the bean is dark. Each coffee has an individual profile, imbued with a taste of place.

Drum versus fluidized bed
Always a hot topic, and there are strong opinions both for and against both styles of roasters.
Drum roaster enthusiasts claim that as the drum rotates the dynamic action of the beans themselves assist with the consistency of the internal drum temperature in the development of the batch. Fluidized bed roaster fans argue that the constant motion of the bouncing beans aids in assuring perfect consistency from batch to batch by  banishing hot spots within the roast chamber claiming that the beans become more buoyant as they lose moisture.
Here is my take.
The job of the roaster and the machine is to develop the flavor of the green bean to its optimum profile. Sugars in the beans caramelize and come to the surface as it roasts. It is important to note that the beans must be allowed to develop in the optimum time and temperature. If the temperature is too high for too short a time the beans will not being roasted throughout. If the temperature is too low for too long the bean can bake.“
Drum roasters develop more slowly and can provide more control over the roast process. Fluidized bed roasters tend to be very consistent and, in my opinion, a little easier to operate. The end result must be a perfect roast. The operator can manage stability and air flow  in  drum or fluid bed roasters.

Dark versus light
Even Starbucks after a few years of success with its thoroughly branded Starbucks roast, saw the light (and sales opportunity) of a lighter roast as markets became more sophisticated and wanted diversity in their beans.
Roasting coffee is a lot like cooking, so let me use an analogy: the grill chef prepares a beef rib eye steak. If chef determines to grill it, for how long shall he do this? If the meat is cooked medium rare it will remain tender, pink, and more flavorful. As the steak is grilling, the tender sweetness gives way to the char taste of the grill. Coffee is like this in many ways.
Take a micro lot - this is a very, very small individual lot of coffee that has been separated at the farm and remains isolated throughout processing, export, import right up until he time it gets to the roaster. You cradle these beans and decide to give them a dark French roast. But now this special coffee has lost its individuality.
Subtle nuances that are a result of the coffee growing micro-regions, much like a fine wine, are developed during the roast process. Each coffee is an individual and must be roasted as such.
The following excerpt is from the International Coffee Organization (ICO) website, www.ico.org, another valuable resource:
All of the flavor and aroma that we enjoy in coffee is created by the roasting process.
Green coffee beans are heated to between 180ºC and 240ºC for 8 to 15  minutes,  depending on the degree of roast required. As moisture is lost, the bean ‘pops’ audibly, rather like popcorn, and a chemical reaction called pyrolysis takes place: Starches are converted into sugar, proteins are broken down and the entire cellular structure of the bean is altered. The heating process precipitates the release of caffeol, or coffee oil, the essence of coffee that we enjoy in the cup.  Since it is also volatile and water soluble, once the coffee beans have been roasted, the flavor can be damaged by moisture, light and especially by oxygen.
Roasting is one part art, one part science and several parts judgment. Too much heat and the beans are roasted too dark and too much caffeol is burnt; not enough and the caffeol is not precipitated. In industrial quantities, the process is carefully controlled, but in smaller quantities, it is down to individual judgment.

Tipping: not just a city in China
If the heat is generated in the bean too quickly, the coffee roasts too quickly and the beans’ full potential does not develop resulting in an ashy, bitter cup. If the bean roasts too slowly, the inside of the bean will remain green while the outside chars, resulting in ‘tipping’. Tipping can also occur in drum roasters when the beans come into prolonged direct contact with the interior of the drum, resulting in burn spots.
Size and density matter when roasting. Certain varieties create large beans, such as Pacamara and Maragogipe, which are also less dense. Because of this, both are very easy to burn or scorch while roasting. Heat is slow to get to the center of the bean while the outside chars easily. These beans must be roasted a little slower allowing heat to reach the center without burning the exterior. Denser beans generally stand up to the roast. Peaberry coffee beans will roast faster due to their small round size. Listening carefully to the “first crack” and monitoring carefully will aid in the roast process.

Cupping: why by weight?
To prepare the coffee for a cupping session, set the grinder to ‘drip’. (12.5 grams of “finely” ground coffee per 150 ml) Sniffing each cup in turn, you evaluate the aromatics. Add fresh filter water just below boiling and sniff again. After four minutes, you get your nose right into the coffee ground crisp before breaking and with one deep thrust, submerge the silver plated cupping spoon and stir three times just on the surface as you deeply inhale. Is the coffee clean and sweet? Then evaluate its other attributes.
Before you cup, make sure you have water, water everywhere, and check the water supply in your lab.  

Common pitfalls
One common pitfall occurs when roasters assume the market wants a darkly roasted coffee for everything and underestimate the need to buy quality green beans. The roaster needs to take time to educate themselves and their customers on the diversity of incredible coffees and their ability to reach a full range of distinct flavor profiles, complimented by the roast, not masked by it.

Storage of green beans
Humidity should be 12%. If unopened, it is safe and acceptable to stack coffee in burlap. But make sure not to store with bean bags resting or leaning against the wall. Air circulation is important. The writer once saw a very impressive storage area in a former flavoring room of a soda pop manufacturing plant. It was completely encased in ceramic tile. Humidity remained constant regardless of the outside temperature.
The moisture of the beans contributes to the way the coffee roasts. Dryer beans roast more quickly, beans with a high moisture content take a little longer.
New crop vs. old crop? Sugars evaporate and basically leave the bean dry over time or if the coffee has been improperly stored, so when heat is applied there is less development, hence less flavor.

Blending for profit, not for taste
Another no-no is when roasters simply blend to bring down the price. Consider the culmination of what you want the final flavor profile to be and then work backwards. Do not assume an excellent wine will taste the same in a glass once you have added water. Just like a fine wine, why would you dilute your coffee?
In closure, pitfalls occur when you believe everything you read and make assumptions. Learning by experience is perhaps the best method while taking into consideration other peoples’ guidance and experience. It is you, the roast master, who determines the coffee’s final fate.
I prefer a holistic approach, allowing the bean to speak to me, to share what intrinsic qualities it has, to tell its story, each bean at a time. It’s a relationship, not only with customers and coffee growers but with the coffee beans themselves.
Final advice: buy the best quality coffee beans available and as the old Jedi warrior Obi-Wan Kenobi might say: “Luke, beware the dark side.”