Popcorn machine made into a high class coffee roaster

Step 3 Roasting beans

And now the roasting.

Initially I though you just needed to roast the beans until you reached your preferred temperature/roasting degree and then you were fine. I tried this and didn't get satisfying results. One time I roasted till 220C and got little carbonized beans.

I came across a site which mentioned the use of a temperature profile. I lost the link, but it looked a bit like this:

-Heat up to 150C and keep it there for 1 minute.
-Heat up to 190C with about 13C/min
-Keep it at 190C for 1 minute
-Heat up with 3C/minute until you reach your preferred temperature.

I tried this profile now twice, heating up till 208-210C and am very satisfied with the end result.

To roast you will be needing:
-Fresh coffee beans
-Your roaster
-A timer
-Scales
-A good thermometer, going up to at least 230C

Put the thermometer in the roaster and fill it with 100g of fresh beans. Turn on the ventilator at max and then turn on the heating coil (always have the fan running when the heating coil is on!!). Make a temperature note every minute. After you reach 150C, control the temperature for 1 minute by fan speed and turning the coil off and on (requires a bit of practice).
Then, heat slowly up to 190C in 3 minutes, keep it there for one minute and then go slowly (3C per minute) to you desired end temperature. Once you reached that, you turn off the coil and put the fan on max untill the beans are below 80C, which takes a few more minutes.

Controlling the temperature is quite difficult, but if you try it as best as possible, you will end up with a nice result. It is important you keep your beans dancing. If the fan speed is to low, the beans will stop and you might get an uneven roasting, of even burn the ones at the bottom . If you can't get the temperature to rise anymore without the beans stop dancing, you need to use less beans or find alternative methods, like putting a cap on the tin or recirculating a part of the warm air.

As adviced, I let the beans stand for 1-2 days before I use them. They would degass during this period, although I never tested if you can drink coffee direclty after roasting the beans.