[Homeroast] Jimma

Robert Yoder robotyonder at hotmail.com
Thu Oct 14 13:57:08 CDT 2010

Thanks, Chris, for the detailed information!  I think this is very useful, and if you do develop a Bean Mass Temperature-indicator, I'd like to see those data plotted along with the others.  Do you plan to use "FarmRoast's" method?
I would like to see how you mounted your Enviro Temperature Thermocouple.  Any chance you might have a picture?
Thanks again, and,
Happy Roasting,
> Date: Thu, 14 Oct 2010 10:44:43 -0700
> From: yakster at gmail.com
> To: homeroast at lists.sweetmariascoffee.com
> Subject: Re: [Homeroast] Jimma
> For understanding the Behmor profiles, nothing beats Ira's BehmorThing
> program available on www.behmorthing.com. I use it to plan and track my
> roasts and greens inventory, it's invaluable if you're trying to get a P2
> temp drop to occur at a given time (though I almost never use a P2 profile
> anymore myself and now just open the door to cool things down). Also, never
> walk away from the Behmor during the roast... it may be tempting because
> it's pre-programmed, but the results could be disastrous.
> I'll keep this somewhat on-topic by using my Jimma roast profile as an
> example in this email.
> Since the Behmor doesn't have a temperature display, it's hard to talk about
> temperatures. It's also going to depend on the voltage available during the
> roast which can affect the heat output. It's also going to vary depending
> on where you measure the temperature in the Behmor because of the air
> circulation.
> The following picture is a roast graph of my roast of the Jimma, I roasted a
> full pound on a 1# P3 B profile which I ended up extending the time on to
> reach my desired roast. It took quite a while to take the full pound to
> first crack, the coffee is tasting very good now but I may roast my next
> batch with a P1 profile which is full power throughout the roast. I have a
> thermocouple taped along the bottom of my roaster that's positioned about
> one quarter inch below the bottom heating element to give me a good idea of
> the heat output of the roaster during the roast. I don't have a Bean
> Temperature thermocouple installed yet.
> http://www.twitpic.com/2xkz9g/full
> You can see that even though the profile (blue line) shows a stepped roast,
> the heat ramps up and is not instantaneous. I pre-heated the Behmor and
> old-style chaff tray for one minute on a P1 profile before putting in the
> beans and starting the roast, so the drop-in temp is about 200 degrees. Be
> careful not to pre-heat too long (more then about 2 minutes) or the roaster
> will not restart after stopping it, and wear Ove Gloves or other protection
> for your hands.
> The hump at about 8 minutes in is when the afterburner and fans kick in for
> smoke reduction. The green bar at the bottom indicates when I started and
> stopped controlling the temp by opening and shutting the door. I started
> early, probably too early, to kill some of the momentum going into first
> crack. I watch the temperature and listen to the roast while adjusting the
> door position to get the temps where I want them. The olive box indicates
> the start and end of first crack. Finally, the dip at about 25 minutes is
> when I stopped the roaster and pulled the beans to quickly cool them in my
> bean cooler. I let the Behmor take care of the cooling in the beginning as
> it's pretty good at getting hte temps down to start with, but when the temps
> drop low enough I pull the drum and restart the cool cycle while cooling the
> beans myself. Here's a picture of the beans cooling:
> http://www.twitpic.com/2x6sgj
> I'm not posting this information to be held up as an ideal roast, it's not.
> This is pretty much a generic roast profile for me that I use for a lot of
> beans as a starting point that works well for espresso and brewed coffee
> most of the time. It may be sacrilegious, but I've actually been using
> profiles that take longer to get to first then the experts recommend on a
> regular basis and been very happy with the results, especially when I get a
> full pound of beans out of the roast in one batch to brew for the week. I
> look at the Quest roaster and it looks really nice, pretty much the opposite
> of the Behmor with full manual control, but I don't know if I'd be happy
> with 200 gram roasts. I've gotten to like being able to come home and roast
> a pound of coffee at night, but I know a more hands-on roaster would help
> develop my roasting skills. I think next time, as I said, I'll use a P1
> profile and open the door to control entry into first crack with my next
> Jimma roast.
> Also note that this is a roast of a full pound of beans. As such, things
> ramp slower and the beans gain more momentum. I can open the door during
> first crack on full pound roasts and see the temperature hold steady with
> the door fully open. With a smaller batch, you'll get to first much quicker
> and the bean mass won't hold the heat so much.
> Hopefully this information will help others understand how the Behmor works
> and how the profiles work, that's the intention anyway.
> -Chris
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