Recovering from a Bean Fire

I was riding high. Visions of gloriously aromatic coffee beans danced before my eyes as I worked my brand new Behmor 1600 roaster night after night. Flush with initial success, I had just set up, and was getting ready to spread my joy to the world. That would be a good time to learn humility, right? And humility arrived, right on cue.

It was midnight. I had just finished a full city roast of Colombia that night, and was getting ready to do a dark roast. I did the mandatory dry burn, cleansing the roaster of any remaining chaff from the earlier roast. I added the remaining half pound of green Colombia beans to the roaster drum, and selected the P1 profile. For those wondering what I am talking about, the P1 profile is a roaster setting that heats the beans at the same heat level for the entire duration of the roasting process, followed by fan drying.

Now the Behmor roaster resembles your average toaster oven, with a wire-mesh drum in the center rotating much like a rotisserie. Halogen elements in the back of the oven roast the beans as the drum rotates. Special vanes inside the drum toss the beans around as they roast, expand and change color. You cannot leave the roast even for an instant, or calamity will ensue. The first crack sounds like popping corn. This is when the chemistry inside the beans shifts into high gear, and the flavors begin to gather. The parchment-like coats starts falling off the beans and accumulate in the chaff tray under the drum. Then the beans go quiet for a while. This is the time the unique flavor characteristics of most coffees develop. If you want a light or city roast, this is where you stop roasting and start cooling. If you want a dark or French roast, you keep going until you hear second crack. That sounds like Rice Krispies hitting milk. The Behmor is an extraordinarily quiet machine, and you can hear the cracks very clearly. Almost as soon as you hear second crack, the oils inside the bean rise to the surface and caramelize, and the beans immediately darken and begin to glisten. You have now arrived at French roast, and there is no going back. Some smoke is normal when you start cooling. Today, however, was different.

Cooling began after second crack, but instead of a few wisps, a thick cloud of smoke rose from the front of the roaster. I immediately tried to reduce time and then frantically hit the power button as the basement was filled with acrid fumes. The roaster just kept going. I disconnected the temperamental machine from the wall outlet and opened the basement door to let in some cold night air. I took the roaster out of the house and let it cool on the steps. As the smoke subsided, I surveyed the clumpy mass of burnt beans in the drum. My troubles had just begun.

The basement smelled like someone had smoked a bad cigar. The roaster was cool, but the inside was a mess. The entire inner surface of the roaster had become coated with a thick, dark, oily coating. I emailed Behmor begging for warranty service, and went to bed deeply troubled. Next morning, Bob from Behmor wrote back with detailed directions to clean up the roaster. It’s not unusual, he said, to have bean fires. His assurance calmed me, and I finally began a post-mortem. Thinking back to the moment of the fire, I realized what happened. I was roasting a hard, high-altitude bean. The beans simply let out too much oil, and that caught fire in the sustained high heat.

The next few nights were spent with an old toothbrush and a bottle of all-natural cleaner, as I scrubbed and scrubbed to remove the oily residue. This was followed by three back-to-back dry burns as recommended by Behmor. Each burn removed a little of the residue, and soon the machine was ready for use again. I roasted a half-pound batch of Costa Rica Tarrazu 1900 to make sure, and the roast came out great. Back in business!

The basement still smells of smoke, but the latest roast has added a chocolate aroma to it. But the best thing about this bean fire was that it gave me a deeper respect for the roasting process. It poked a giant hole in my ego, and showed me that I still have a long way to go before I truly master this art. The Behmor 1600 is a great machine, and I recommend it to anyone that has a serious interest in home roasting. I will steer clear of the P1 profile from now on, and stick to the gentler P2 profile even with the hard beans. I’ve had more success with that anyway. I’ll continue to test and sell my roasts and blends, but will try not to be cocky about it. If you ever find me getting too brash, whisper “Bean fire!” in my ear and I’ll be forever grateful.

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