I am glad to see this post come back to life. I have been playing around with Gene Cafe roasting profiles for a long time. It is challenging since converting the conventional wisdom relative to roasting profiles to the Gene is not simple. Add to that the lack of ability to get a probe in the bean mass and you have a tough job.
For most roasts, I dry at between 300 and 360 degrees for about 5 minutes. I then have an intermediate temperature of between 440 and 450 degrees for another 5 minutes and a finishing temperature of about 460 degrees until the roast ends. This allows for several minutes of flavor development between first and second crack. This profile gives nice body and is particularly good for City/+ roasts since it slowly builds without giving too much momentum to the roast.
I have also had decent success drying at the same rate as above, then cranking the temperature up to 480 until 1st crack +30 seconds, and then finishing at 460 degrees. However, this profile can lead to thinner body and more residual acidity, which may or may not be what you are after.
Recently I have been playing around with longer drying times/longer times at lower temperatures, and the results have not been good. I have also compared leaving out the intermediate temperature step in the first profile I mentioned, and the coffee suffered.
For those Gene roasters, I keep track of profiles at my blog:
http://scottoscoffeeandtea.blogspot.com/As an aside, I have a friend of mine who is a Chemical Engineer trying to work out some equations for the relationship of the environment temperature read by the Gene to the actual bean temperature. It is definitely much lower, but I would like to have some sort of insight into it.
-Scotto
