Over the last 20 years or so I have used a wide range of equipment, from air popcorn poppers to $thousand+ programmable machines. After all that this is what I ended up with, a 1-pound roaster that lets me dial in perfection:
Bottom is cast iron dutch oven, top is a modified cast iron skillet. It is 13 pounds of thermal mass against a 1 pound of coffee beans. The egg-beater looking thing is from a Kitchenaid mixer, modified so as it is spun by hand around the hole on the lid, the shape follows the contour of the base while the opposite side reaches the center of the container. The hole on the lid is dialed in so it fits through it. The way I use it is by preheating it to 400 degrees (takes a while to warm up all the way to the lid) which lets me hit first crack around 4.5 minutes without charring the beans. The holes on the bottom where the final dial-in step to allow of better temperature control. It largely relies on the ungodly amount of thermal mass but it had a delay in raising the working temperature inside of the chamber; raising the flame had about a 20~30-second delay before the beans would really feel it. This was the best way to have my cake and eat it too; the thermal mass plus more direct raising of the temp.
Roasting the most perfect cup of coffee requires very precise attention to details throughout the roasting process:
- Ramping up to first crack. The beans go from green to just beginning to develop color. They are full of humidity so there is a limit of how much heat you can apply because they just keep āsweating it offā. But if you put too much heat you end up charring the outside, if you donāt put enough heat you end up ābakingā the beans instead of roasting them. The best metric for success is hitting first crack at around 4 1/2 minutes of roasting with an even roast across your beans. There are specific acrid notes you can detect in your coffee from screwing this step. This is the hill stovetop methods come to die on, while air roasters have an easy time pumping the correct amount of heat.
- First crack. Beans are losing humidity and beginning to pick up heat. You want this step to last at least 2 minutes. If you rush through it youāll lose a lot of body in the cup, ending up with a thin profile and no mouth feel. You see a lot of āsmokeā coming out but at this stage it is mostly vapor. Towards the end you have to start cutting back on temperature as the much lower humidity allows the beans to really soak up heat, which can lead to them getting ahead of you.
- Between first and second crack. This is a crucial point to realize the full potential of the cup. What you see at this stage is the actual smoke from the roast and the nose can tell. Oils are beginning to migrate, and you do not want to rush that. This is also the step you can tweak the most in order to get the best expression based on the bean variety you are working on. As a matter of fact I ended up settling on a stovetop roaster because of how it lets me be 100% hands on. You want to make sure you spend a good amount of time at this juncture, you want to make sure you are still gaining heat and not baking your beans, and with the stovetop I can monitor all that by the amount of smoke it generates. I donāt want the smoke to stop (baking mode) nor I want too much smoke (burning mode) I can hit that note where a wispy amount of smoke is being generated which tells me that my beans are just soaking up enough heat to keep that going. You really want to spend at least 5 minutes in-between cracks, but this is really where things turn into an art form. At the end the proof is in the cup.
- Second crack. It gets complicated to consistently hit light roast pre-second crack, as you have to rely on temperature measurements. But I usually donāt roast those so for me life starts at second crack. At this stage your beans are so dry that you can simmer through the previous step, and at the end just raise the temperature and hit second crack in a hurry (the holes on my design I talked about, this is where I found out they helped). The beans are so ready to soak up the heat that I can remove the lid and finish my roast in the open.
There you have it; many hours wasted chasing the perfect roast. At the end not even the $1,400 Hottop was able to cut it, but this one did.
But with a caveat; having the better temperature control the lid provides allows me to roast a slightly larger batch. Your roaster will have a capacity, dictated by how much you can roast without ending up unevenly charring beans. With 1 pound I can watch my beans gaining color very evenly. If I put 1 1/2 pounds and still try to make it to first crack in around 4 1/2 minutes, the batch doesnāt roast evenly.