Roasting the Green, a Sensory Experience: Coffee Roasting Part II

In teaching a young adult the fine art of roasting green coffee beans sourced from around the world, I realized that the roasting process was all about the sensory input and the true artisan touch is in assessing the beans at every stage.


The green coffee beans are analyzed visually for defects:

  • Aged/Floaters (Ripe green coffee beans that are ready for roasting are dense and sink in water. The first step in coffee production separates the floaters from the sinkers, roasting the floaters and allowing the immature sinkers more time to ripen.)

  • Full Sour (These defects are caused by waiting too long between picking and de-pulping, an overly long fermentation process, or storing the beans with a high moisture content.)

  • Damaged Beans (Green coffee beans may become damaged from fungus, insects, and overexposure to light.)

  • Wrinkled (Typically a result of drought during the growing process.)

  • Cherry Pulp (The pulp/rind of the coffee berry should always be removed during the first stage of coffee processing, before drying, and before the green beans are shipped to be roasted.)

  • Broken, chipped, or crushed beans

  • Foreign Material (nails, rocks, wood)

Before I began my coffee roasting journey, I had no idea I would be visually analyzing for defects like these! At Cody Coffee Roaster, any defect and the Green Coffee Broker is informed and the beans are returned.

About the Coffee Roaster

Coffee roasters come in all shapes, sizes, models, and from a multitude of vendors. Cody Coffee Roaster uses a 10kg Mills City Roaster allowing us precision control in every batch, perfect for our growing coffee demand.

Let's begin by highlighting a few key parts of a coffee roaster:

  • High voltage electrical source

  • A heat source, natural gas

  • Hopper (Where the beans are initially dumped into the machine)

  • Drum (Rotates the coffee beans and heats them during the roasting process; this is where most of the magic happens.)

  • Viewing port (Window on the end of the drum where beans can be viewed throughout the roasting process.)

Viewing port (left) and sampling port (right)

  • Sampling port (Allows for beans to be pulled out while being roasted, looking for color changes and aroma.)

  • Thermocouples (Measures how the probes react to environmental and bean temperature to determine the roasting temperature.)

  • Cooling agitator (Stimulates cooling after roasting)

  • Fans, Motors

  • Chaff collector barrel (Collects the dry skin, known as the chaff, that comes off during the coffee roasting process.)

  • Smokestack (Similar to a wood-burning stove, roasters have a smokestack to allow the smoke and heat to escape the drum.)

The complexities of a coffee roaster can be intimidating for both the beginner and the novice.

Before every roast, a visual inspection is performed and all parts are cleaned for safety purposes and quality control at Cody Coffee Roaster.

The Roasting Process

The actual roasting is where all of the senses are used. First, the green coffee beans are weighed according to the batch. Next, the charge temperature is dialed in, this is the temperature of the drum before the beans are added. The charge temperature is responsible for a lot of the roast's flavor profile. For our roasting purposes, the charge temperature is 375 degrees Fahrenheit. The green cof