- Created: Tuesday, 20 February 2007 13:08
- Written by colin newell
Walking around a coffee plantation, in the Fall of 1996, helped me connect the dots in my lifelong fascination with the coffee bean. There was something significantly more real and palpable about the coffee plant - running my hands across the waxy green leaves and looking at the berries in various shades of green and red. I spent the good part of an afternoon exploring a processing plant where the red cherries are stripped of their fruit and laid out to dry. Further drying and milling removes a remaining silverskin putting the precious beans that much closer to their inevitable date with a coffee roaster somewhere.
And even though a lot more goes into the cultivation, tending, production and harvest of the delicate berries, this one day of activity for me brought a sense of the Gestalt or global personal understanding of what coffee means to me.
Roasting coffee for the first time (and every time after that) had a similar emotional impact. Roasting 3/4 of my body weight in 4 hours, one afternoon, gave me a collective grasp of the Zen of coffee-roasting. Truth is, when you are roasting coffee (in any quantity -- ounces or pounds) it is You and the beans. Nothing else matters. Nothing else should interfere with your focus. In some ways, roasting coffee is like driving a car or flying a model plane (or a real one...) There is no room for inattention. Thankfully, when I first started roasting small amounts of green coffee beans I had already read a couple of books on the subject and picked a few brains.
Being prepared is important, very important. Remembering our discussion from the previous chapter or two; ventilation is key, a suitable work space and an appropriate air temperature for the roaster to operate in (Suitable roasting environment temperatures are anything between 60 and 90+ degrees). Too cold, and the coffee will not roast properly. I am not sure what happens when you are roasting in an ambient temperature above 100 degrees - cannot be healthy for you or the roaster I do not suppose!
Back to the model airplane analogy for a moment to help press home a point. I spent a long time flying on a flight simulator before I got behind the wheel of the real thing. Why? Because crashing and burning is never fun when you are really behind the wheel. And as I said before, coffee roasting (however exhilarating and spritual an activity...) is way more demanding and exacting than you think. And I am talking to you and you and you!
I started small - on a corn popper that I modified (picture in previous chapter). I figured with 4 ounces of green beans (a small palm-full) how could I go wrong? Luckily, I had read my face off on the subject and was prepared for any disaster. Yes, I had an industrial grade fire extinguisher on hand and I know how to use it (had an afternoon fire-fighting course under my belt too - never used that training thank heavens!)
First time roastmasters (oxymoron) will be surprised to find that coffee roasting is actually more than eagle-eye attention to detail from the visual perspective. As coffee goes through the evolution of the roast cycle, it releases a myriad of scents - from fresh cut grass to brown toast to unique organic chemical odors. Surprisingly (to me), it does not smell like coffee at all - at least initially and after the roast is dumped and cooled. There is a wild matrix of chemical changes happening with coffee when it is being roasted.
The chemistry of coffee roasting is complex and I will not go into that much detail... A little bit. So -
Much of what happens to the bean during the roasting process can be explained with a few minor brush strokes. The bean loses lots of its moisture, which means it weighs less after roasting and the beans are actually larger than before. It loses some protein and about 10 to 15 percent of its caffeine. Chemicals (Molecules) vanish and new ones are created. It is a true ballet of organic chemistry - at last count there are more than 500 molecules in the average roasted coffee bean. We are not entirely clear on the nature of many of the compounds in coffee. And apart from the caffeine and how the fruit acids contribute to the overall flavor profile, a lot of what goes into the coffee bean is still shrouded in mystery. The sugars in the roasted coffee bean (yes folks there is sugar in coffee) go through quite a few transformations depending upon the degree of roast. Some coffee origins, like Mexican coffees, benefit from a deep dark roast - others do not. More on that in the next chapter!
Roasting is simple in theory: The beans must be heated, kept moving so they don't burn or roast unevenly, and cooled when the right moment has come to stop the roasting. Coffee that is not roasted long enough or hot enough to bring out the oil has a grassy, nutty or bread-like flavor. Coffee roasted too long or at too high a temperature is thin-bodied, burnt tasting, and industrial-flavored. Coffee roasted too long at too low a temperature has a baked flavor. That is because you have just baked the coffee, not roasted it! Of course this will not happen if you are using a proper roaster, homebrew or otherwise.
So - what is the first roast like? In the 9 to 12 minutes of your very first roast, time will seem to last an eternity or it will flash by like a speeding car. What is important is that you try and take in as much of the action as possible, paying attention to what should be happening (based on what you know from self-study prior or actually roasting any coffee) and what you actually see before you.
If you are using an i-Roast or Hearthware style fluid bed roaster, you will dump in the green coffee and power-up. The coffee and the unit will heat up consistently and gradually - like it should. Using a modded corn-popper, you can probably do a minor pre-heat of a couple of minutes. Keep in mind that a home corn popper without green beans in the hopper or roast chamber can quickly heat to 500 degrees or so - scorching the beans. So be careful!
Within the first 3 or 4 minutes of roasting you will actually smell things before you see things. Typical early odors include grassy, clover, leguminous or green. Between 4 and 5 minutes (times approx.) you will notice a distinctive yellowing of the coffee. In minutes 6 to 7 you will start to detect the scent of bread in the toaster... Not a bread smell but a toast smell. After 7 to 8 minutes of coffee roasting, the beans will start to take on a coffee looking brown color. Soon you will hear a popping or cracking sound. We call this 1st pop or 1st crack. There is a lot of physical stuff happening inside each bean as it loses moisture. The actual fibres that hold together the beans are tearing as they expand. This will continue as a process called pyrolysis kicks in. It is an internal fire that happens as the roast progresses. At this point, and it is very important to understand this - When pyrolysis starts, the roasting beans are now releasing energy into the area around them and into adjacent beans. Think of charcoal that has been lit - except that the coffee is not really burning. It is only minutes away from a potential flash point OR real fire. This is also important to remember. Read: Fire hazard!
Note to self: The roaster is putting energy into the beans and the beans are putting energy into themselves in the form of heat. Pay close attention. Things start to really speed up now.
Between 9 to 12 minutes of a coffee roast, the color change will be visible every handful of seconds - darker and darker by the moment. Do yourself a favor. Stop the roast or enter the cooling cycle before the coffee gets too dark or prior to droplets of oil appearing on the surface of the beans. Work up to the dark roasts gradually!
In the next installment we will talk about:
-ending the roast
-cooling the coffee
-dealing with chaff
-what to expect as far as flavor is concerned.
Colin Newell has been talking and writing about coffee since 1994 - an awful long time in Internet years...