I decided to try roasting some coffee in my convection toaster oven, out of curiosity. It more or less worked. The roast was totally inconsistent but it was in a nice range from light to dark and everything in between. I havent tasted the coffee yet but will do tomorrow. I took a video of it and posted it on youtube. i sped it up so that you can see the beans roast and expand. its pretty cool. it was not possible to stop the roast by colour or crack because it was so inconsistent so i stopped it purely intuitively.

here are a couple pictures. note that 1/2 of the roast is lighter than the other. i think this has to do with the convection fan, which was on the side that the lighter roasted coffee is on. the fan is blowing hot air under the beans and so its hotter on the far side hence darker. a more consistent roast may be possible without using the convection feature. also i used it on "bake" mode with only uses the bottom elements. so using the top and bottom elements on a non-convection mode might help. the convection toaster oven i have also has a rotisserie attachement so it might be possible to roast in that and produce something really nice.

so much for my hottop...

Hello there,

I am an oven roaster. I tried small electric ovens, both convection and non-convection, and I tried large ovens, both electrical and gas-powered. I also tried to use home-made drums in both small electric ovens and large gas-powered ovens that came with a rotisserie, so I can say that I tried many ovens in many situations. The best oven I ever tried was the large and expensive GE oven of my grandmother which has digital control of temperature and a digital reading of the temperature inside. This large electrical oven has a sophisticated convection that is only used automatically by the oven's circuit to distribute the heat evenly within it (which means that there is no constant flow of air inside the oven). My roasts in that oven were legendary and I still remember once roasting Ethiopian beans in 40 whole minutes with the beans coming out light. They were light in colour yet mature, soft, caramelly and never ashy or astringent. However, that was my grandmother's oven which I do not have at home (1346km far from my home). At home, I had the best results with a small non-convection electrical oven with a rotisserie using a simple drum that I made. The fact that oven comprises a system of slow heat transfer what makes me think that intentional movement of air is dangerous and unnecessary as it will dry the beans and lead into the development of ashy tastes before the roast has progressed as needed. Thus my advice in ovens in general is to avoid using convection (stream of moving air) unless: (1) the flow is very weak (2) you have mechanical agitation of the beans (somehow) or (3) the batch size is incredibly small.

I'm not sure I understand your advice. If the roasts were so good in your grandmother's convection oven, how is air flow dangerous?

I use to use a large toaster oven. I built a stainless drum, added a geared down motor to spin the drum around 30rpm. I insulated around the inner oven walls (not in the oven but between the outer oven walls and the shell of the oven) and added a 800 watt auxiliary heating element. It worked quite nice, still have it in the basement. I ended up getting a Hottop but my home made drum roaster worked just as good and I had more control over temperatures. I could get second crack in around 25 min with a pound of coffee in the drum, faster if I ran a lower charge.

another_jim wrote:I'm not sure I understand your advice. If the roasts were so good in your grandmother's convection oven, how is air flow dangerous?

That oven is not quite convection, which is why I elaborated a little about its way of operation. It has fans on the sides for moving air but these are not controlled by the user, and they provide no sensible air flow when you are in the baking mode, which is the important point. It seems that these fans are used to ensure an even distribution of heat inside the oven, which is supported by the very uniform and constant temperatures within. Usually in ovens, even when you use a low-heat setting, the heat will keep on accumulating because the oven understands a low setting as an infrequent way of turning the heating element on, which will not prevent the temperatures from rising eventually to high levels (and even when they are using some thermometry circuits heat will eventually build up). In that oven however, it was truly temperature-controlled which meant that I could keep the temperature fixed at 415 degrees for 25 whole minutes with no apparent temperature build up (no smoking, no scorching). Movement of air not only accelerates the transfer of heat but also accelerates the drying significantly, so in the case of my 40-minute roast, I doubt that true convection could have allowed for such light-coloured beans that are devoid of charcoal flavours.