If you want to be a good roaster, you need to know how to read the green coffee. Without understanding the material that you are working with, you will never be able to consistently produce top quality roasts.
Now if you're lucky enough to have a moisture and density meter, that makes things easier. If not, you can still use certain visual cues to help you determine a rough idea of the green coffee. Watch the video below to learn how.
Making Sense of the Numbers
Once you've measured both the moisture and density of the coffee, you can start planning out your roast. The density of a coffee references it's ability to conduct heat. Just imagine a ball of metal vs a ball of paper, which do you think will respond better to being in a burning hot drum? Obviously the metal ball right? The ball of paper would just burst into flames and turn into ash. You wouldn't want your coffee to become ash would you? This is similar to how your coffee would react inside the roaster.
While not as extreme as a metal ball vs a paper ball, a denser coffee bean will be able to handle heat input much better and more efficiently compared to a less dense coffee bean. Ergo, you can apply more heat. The less dense bean will have a higher tendency to burn, charr or get scorched like the ball of paper and would fair better with a smaller heat input.
The second variable to consider is the moisture content. Water, is also a good conductor of heat, albeit, only until 100°C where it turns into steam and becomes less efficient of a conductor. So the moisture content gives you a clue as to how to approach the beginning of your roast. Higher moisture, higher heat. Lower moisture, lower heat. Pretty simple right?
Now of course, there are other variables at play which are important too. 13 to be exact. If you're interested in taking your roasting to a new level, we teach all of this in our Ultimate Roasting Course. Otherwise, you can also enjoy the fruits of labour from other top roasters in Singapore at beans.sg