Roasts N Posts

Magic happens during roasting. The series of chemical reactions that changes a green, grassy-smelling bean into an amazingly aromatic chocolate-colored product which is capable of yielding some of the best beverages in planet earth. This is an Art with a lot of science behind it, and the science happens in very predictable waLike coffee bean comprises of water, oils, proteins, caffeine, organic acids, tannin, sucrose and vitamins, all of which either change or decompose into other compounds during the roasting process.Like what I shared to participants in the Barista Workshops that I previously conducted; if Chemistry was taught in school with coffee as a subject, I will sure aced it and able to differentiate exothermic to endothermic.

Cracks? Yes, cracks! If you're new to roasting, the cracks may surprise you but it helps as we won't be able to gauge roast degree by color alone. Not only are roasting appliances blessed with an unobstructed view of the beans inside, but when you're staring at varying shades of brown for 10 - 20 minutes, you tend to lose your point of reference. Experienced roasters rely on several different things to gauge the timing of a roast: color, smell, cracking, and well-kept roasting logs.

First Crack

First crack is nature's unofficial marker that the beans have progressed into the range where the roast could be stopped, and deemed complete. A roast in a style this light, though, doesn't appeal to everyone - tending to taste underdone and sour. First crack generally occurs at approximately 400 degrees Fahrenheit, and is marked by a rapid expansion of the bean, where moisture and gases from within the cellular structure are released, creating a well defined popping sound - similar to popcorn. As the roast progresses, first crack speeds up and becomes fairly rapid. The beans become gradually darker, until first crack has subsided, and the beans usually go quiet for a short time before the next set of cracks begin. This reaction is exothermic, which means that the beans give out heat.

Second Crack

Second crack typically occurs at approximately 450 degrees Fahrenheit. At this point, the beans are continually absorbing heat, and their cellulose structures begin to rupture, resulting in a series of cracks called second crack. These sound markedly different than first crack. They are more muted and higher in pitch - almost a snapping or crackling sound. The onset of second crack is the unofficial cue to call it quits, unless dark roasts are your game. As second crack ramps up, the inherent regional flavors of the bean quickly succumb to the generic taste of the roast itself, fading out until they are completely gone and replaced by the burnt taste of charcoal. Coffees made from roasts this dark are very thin and weak, having given up all of their aromatic oil inside the roasting chamber.

How Do I Time My Roasts?

This was the question that Rizuan ( a roasting trainee that i am currently guiding) asked one fine day, in between roasting.The short answer is experience. Unfortunately, that isn't much help to a new coffee roaster, who has none to draw on. I went through my learning by reading books and observing various Roast Masters at work before attempting to 'knock the wall and continue knocking." I animatedly recalled an incident where trying to control a roast when it was already well after 2nd crack, it got so heated that when I released it and dump it into the trash bin, the trash bag melted and caught fire!
My advice is to roast to a nice medium roast - one that will work well for pour overs. How do you achieve that? Listen for first crack. This is point where the beans will have given up their green color, and taken on a very light brown, or tan, shade. The exhaust smoke will have started to smell less like grass or hay, and developed a cooking smell, with hints of the warm coffee aroma you are used to - still earthy, but closer to what you may expect from a finished roast.

Once first crack starts, let it go for a bit. I read once in a roasting book that the average time between first and second crack is approximately 4 minutes. Try to aim your roast for somewhere around 2/3 of the way between the time first crack started, and the estimated time based on the roaster's documentation. If not, quench the roast as the cracking ramps up and becomes quick and consistent (similar to the way popcorn pops). Once you have achieved this rolling first crack, stop the roast.

How Does it Taste?

When you're ready, grind the beans and have a little of faith in the brew. You'll know instantly, based on your own taste preference, if you have gone too far, not enough, or hit the mark perfectly. Next time, try roasting a little darker, or lighter, and see what your taste perceptions are then. Of course if you have roasted a whole bag of 60kg and the taste is far from your imagination, good luck to both you and the wallet.

A Few Notes About Freshly-Roasted Beans

Freshly-roasted beans need to degass for the first 24 hours. During this time, the beans are releasing Carbon Dioxide, so leave them in an open container for the first day. After that, it's safe to seal them until use. This is also known as the curing stage.
Freshly-roasted beans always require a resting period before the flavors fully develop and mature. This isn't to say that you can't brew coffee with them during this time (though purists might disagree), just be aware that for the first 48 hours, the taste is constantly changing and evolving - less refined and a little more muddy than it eventually will become. Once the beans have rested, the flavor profile will have matured, and found its equilibrium. All of the delicate flavors and undertones will be distinct and discernable on your palate.Consistently for me, most of my roasts be it a blend or single offering peaks nicely over the fifth day.
If at all possible, store your beans in an opaque container. Light is an enemy of bean freshness, and should be kept from the beans when possible. Of course you have to also eliminate other factors like Heat, Moisture and Oxygen.
Expect your beans to retain that amazing fresh flavor profile for up to a week. After that, they will slowly degrade, and lose their more delicate flavors. It is good to continue tasting it so the next time, you are able to share how your coffee actually fare as another day goes by. For me, I continue tasting it up to the 25th day although the chances of these coffee being left on the shelves that long is so rare, that it never happens! :)

Where Do I Go Next?

Experiment and have fun! Jump at every opportunity you have to roast and learn roasting. Go visit other roasting cafes and make purchases of their offerings. Some are real friendly and always willing to share. Remember, that perfecting the art of roasting involves drawing on your past experience - with the beans in question, the roasting equipment you use and the culture you adapt. Having a vigilant assistant at your side that excels in showing you the timings of previous roasts, debating your calculated actions and observing the temperature will help you too in every roast to being your own personal perfection! For me, I have been lucky to have then Sham and currently Fadhly by my side. Go find yours today!