February 07, 2019

Variables Involved in Roasting

The roasting process can be very fluid and different approaches may need to be considered on a day to day basis in order to achieve a specific roasting profile. There are many variables to consider before you even drop green “unroasted” coffee into a roaster. The first of course is the coffee itself. Where does this coffee come from? What elevation was it grown at? How was this coffee processed (washed, semi-washed, natural)? What is the bean density and moisture content? What is the coffee varietal? What is the age of the coffee? These are very important artifacts in the life of the coffee to consider when brainstorming the perfect roast profile to bring this coffee to its potential.

coffee plant

Once the coffee arrives you must then put together a roast profile. Keep in mind, there are different types of roaster’s on the market that will apply heat to the coffee in various ways that involve convection and conduction. A roaster must first understand his or her equipment thoroughly in order to effectively profile a coffee. Based on the information previously stated above, a roaster can then make some educated guesses on how to roast the coffee. What size batch will I roast? What is the ratio of bean mass to ambient air in my roaster? What temperature will I charge the coffee at? How much airflow will I apply? At what time do I plan to hit first crack? What will my rate of rise be throughout the roast? How much development time do I plan to have? What roast level do I plan to achieve? As you can see there are many things to consider and without keeping notes and logging your data it will be hard to evaluate the success of a roast.

coffee roasting

When you decide on a game plan for how you wish to roast this coffee you then have to consider many changing elements that will ultimately help guide you through the roast profile you envisioned. What is the temperature in the space in which you will be roasting? What is the humidity? How long did you roaster warm up for? Is this my first roast of the day? What did I roast prior? How long did it take to cool the coffee? There are many things to consider on a daily basis that might greatly vary over the course of time and the life of a coffee. And while all of this information and data is extremely important the real test comes down to one thing. How does this coffee taste?

sorting coffee

The most important thing you can do is taste the coffee and objectively evaluate the roast. Certain flavor profiles can speak to specific roasting profiles, so have your data handy. There may be qualities that you enjoy or dislike that can take you back to the drawing board. Once you land on a roasting profile that you believe is ideal for that coffee you must learn to repeat it consistently. As coffee ages and as the weather changes your approach will also change. You may have a completely different approach to achieve the same flavor profile over time.  This is what makes coffee roasting so appealing to me is that there is no absolute and you are always learning more.