Features: Can produce Full City to French roasts. Beans are not easily observed as other methods. Oven vents smoke. All ovens produce uneven roasts, which can actually add to the complexity of coffee flavor, but plain ol' electric ovens will roast too unevenly. The best oven I have roasted in was a very old, small chambered oven that could really put out the BTUs! Roasts more coffee per batch than any other method. All you need is a stainless steel wire mesh collander or a perforated pan and an oven. And heck, it's cheap to try it out! But it affords only a small chance of success in terms of roast quality ... really, try an Air Roasting method such as the air popper.
What You Need: A gas oven. A perforated pan, a vegetable steamer (the ones with the folding leaves that you normally place in a pot), or a stainless steel wire mesh collander (sometimes sold as a collander/strainer). The later is by far the best, allowing greater air movement around beans and producing more even roasts. It is available for about $5 - $9 at Target and other stores. A big spoon, a metal collander for cooling (unless you're roasting in one), and oven mitts.
- For vegetable steamer, place on cookie sheet and cover with coffee beans spread only one layer deep. Have all your supplies within reach. For perforated pan or wire mesh collander spread beans evenly one layer deep, close together, no cookie pan underneath.
- Preheat oven to 500 degrees. Use oven thermometer to be sure.
- Place beans on middle shelf. Wait about 5-7 minutes for the "first crack", then 2 minutes more to start checking for color. Crack the oven open quickly if you must. Oven roasting is slower than other methods, but if it takes more than 12 minutes to reach the medium brown color then you should turn up the heat to 520-530 as the initial temperature for the next batch. If a batch takes more than 20 minutes it will taste flat.
- If you're using a mesh collander, I recommend opening the oven every 1 minute and shaking the beans around. Try to do it quickly and not let too much heat escape.
- Put on those oven mitts, and dump the beans into the collander.
- You want to pour the beans out when they are a tad lighter than the color you desire, since roasting continues until beans are cool.
- Agitate beans in metal collander or bowl with a big spoon until they are warm to your touch. You may need oven mitts for this. You may want to walk out to a porch to aid cooling and let the chaff blow away. Otherwise, you'll want to keep the collander over the sink.
- If beans have chaff still attached to them, simply agitating them in the collander should remove it. Blow lightly on the beans while shaking them and the chaff will fly off.
- Coffee should be stored out of direct light (and not in a fridge or freezer) in an airtight glass jar, but with a fresh roast, wait 12 hours to seal the jar tightly; it needs to vent off C02.
- Warm, fresh roasted beans are wonderful, but the coffee attains its peak 4 to 24 hours after roasting. If you store it as recommended, we'll call it fresh for 6 days. When you open that jar in the morning, you will know what fresh coffee truly is.
Modifications and Refinements: We recommend Home Coffee Roasting by Ken Davids for more detailed roasting instructions, and a "convection oven" method. Check out the Lucidcafe link for excerpts from this book.