Roasting Update

I continue to enjoy roasting my own coffee. My batch size is ~65g of roasted coffee, which only lasts me 2–3 days, so I've been roasting several times a week. A couple of weeks ago I decided to modify the popper by bypassing the thermostat, which automatically shuts off the heating element when it gets too hot. I want the popper to get really hot, so the thermostat had to go. One piece of heat-shrink tubing later, the popper was back and better than ever. It now gets hot enough that I don't need to use the lid at all, which gives me a better view of the coffee. One of the best parts of homeroasting is watching the coffee change color as it roasts.

This is the Costa Rica. The coffee starts out a pale shade of green.

 In the first stage of roasting, the beans turn bright yellow.

As the roast continues, the beans darken to golden brown.

The beans here are nearing first crack. At this point I stop shaking the popper. Shaking the popper in the beginning lengthens the early stages of the roast for more flavor development and helps to ensure evenness.

Once the beans have reached the desired roast (this is Full City, I think), they should be cooled as quickly as possible. The most effective method I've found is to swirl them around a colander (convection cooling) until they're merely warm to the touch, then spread them onto a flat metal surface (conduction cooling) until they reach room temperature. After cooling, I put the coffee in a labeled and dated mason jar. It's important not to seal the jar fully, because the beans release a lot of CO2 after roasting, and exploding jars are no fun.

Since I don't have any way to directly measure the temperature of the coffee as it roasts, in order to gain control over my roasting I try to keep track of as many variables as I can. The easiest way to do this is to keep a log.

Coffee	Ambient˚	Mass (1)	Mass (2)	Shaking	1st Crack Start	1st Crack End	2nd Crack	Pull Time	Notes
Java				2:00	3:45	5:00	6:00	6:00	Blech!
Burundi	86F	75g		4:00	4:17	5:20		6:05	Good, but more mild than lighter roast
Brazil NP	84F	75g		4:00	4:00?			5:10	Still very uneven color, but balanced flavor
Burundi	82F	75g		3:54	3:54	5:17		5:17
Java	83F	75g		5:00	5:15	?		6:55	A bit ashy, but drinkable
Java	88F	75g	62g	4:00	4:45	6:00?		6:30	Good balance
Costa Rica	79F	75g		3:00	3:40	4:55		5:10	Pretty light, definitely city
Costa Rica	76F	75g	64g	3:30	4:18	5:45		6:30
Costa Rica	76F	75g	66g	4:45	5:26	7:09		7:26	3 stops before 1st crack

As you might be able to tell, I haven't had much luck with darker roasts in the popper. I'm not sure if I've lost my taste for dark roasts or if the popper just roasts too quickly to produce a good dark roast. I suspect it's some combination of the two. In any case, I'm happy with the results I've been getting stopping the roast 10 - 60 seconds after the end of first crack (corresponding to a City – Full City roast). I've also tried going lighter, but the very light roasts I've tried (stopping the roast before or during first crack) have been too bready and mild for my taste. The Burundi is definitely my favorite of the four coffees I got from Sweet Maria's. I've discovered that Jones Coffee Roasters (Pasadena) and Klatch Coffee (Upland) also sell green coffee by the pound. I'm excited to get more!

Update: Jones Coffee Roasters no longer sells green coffee. Ordered 5 lbs wet processed Guatemala, 5 lbs wet processed Ethiopia from Sweet Maria's.