I was in the back room bagging up some breakfast blend when I heard shouting from the café. At that same moment, I smelled smoke and knew that my batch of Sumatran had caught on fire. I dashed to the roaster, flicked off the gas burners and closed the vent. I knew the routine. This had happened before. The cloth and rubber belt had broken, the drum stopped rotating and the beans ignited inside, fanned by the air being sucked in through the vents. Now my hope was that the flames didn’t make it into the chimney and light up the chaff that had no doubt built up inside. If that happened, we’d have to evacuate the café and call the fire department.

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Despite the long hours, sweaty work and low pay, roasting coffee remains, to this day, the coolest job I’ve ever had. I moved to Minneapolis in 1991 to finish my English degree. One thing led to another and my four-year degree stretched into seven years, due in no small part to my contentment with my day job. What started out as a part-time barista gig making overpriced lattes for 9-to-5ers became a full-time roasting job, and that diploma didn’t seem that important. Never mind that I went home stinking of stale smoke, with grease and coffee grounds under my fingernails, and couldn’t sleep due to the countless sample cups I’d had during the day. Coffee roasters were the Top Gun fighter jocks of the café culture, and I’d reached the top of the pyramid.

The end of a roast is dramatic. The front door is opened, the cooling tray arms start spinning and the steaming heap of hot, crackling beans comes spilling out into the tray, smelling like Heaven.

One point of clarification: a coffee roaster is both a man and a machine. So while I lent the human element, the real star of the show at the café where I worked was the 1957 Probat LG12. The Probat was a German-made temperamental warhorse that looked its age, sitting in the corner of the café surrounded by 50-kilogram burlap sacks of green coffee. Its matte-black high-temperature paint was peeling and cracking, and knobs and handles had been improvised over the years, giving it a rather battle-worn aesthetic. But while newer roasters had electronic ignition, digital displays and decorative exteriors, in capable hands, the old Probat still produced the most sublime roasts thanks to its seasoned drum and highly adjustable flame rail.

Most gas-fired, direct flame roasters bear a family resemblance. A funnel-shaped hopper on top holds the green coffee and feeds down into the rotating perforated drum inside, which keeps the coffee dancing over the rail of gas flames below. A heavy half-moon shaped front door opens to release the roasted beans into a perforated cooling tray that has spinning arms that keep the coffee moving as it cools. Below all of this is a chaff collector that accumulates the outer “skin” of the beans. The overall appearance is one of a science experiment or undersized locomotive.

I still remember the morning routine to bring the old Probat to life. The first order of business was to vacuum out the chaff collector. Depending on the previous day’s volume of work, the amount could be minimal or mountainous. But it was important to be thorough, given the highly flammable nature of the chaff itself. Next up was removal of the heavy cooling tray in order to lubricate the massive gears that drove the arms around. Both of these tasks were loud and physical and all done in full view of the suited commuters queued up to get their travel mugs filled; there was something oddly satisfying about doing this dirty work in front of those who were headed off to sterile cubicles.

Once the roaster was re-assembled, it was time to fire it up — in a specific order. First, the circuit for the motor was switched on. Then the gas valve opened. Next, the pilot light valve had to be pressed while a long-necked lighter was inserted up under the drum to ignite the pilot light. Once that was lit, I’d pull down the valve handles to send gas to the rails beneath the drum and switch on the motor to get the drum spinning. The whole routine was akin to starting an old car or installing a hot water heater. Once it started warming up, I’d put together the day’s roasting plans, based on the café’s needs, for both bean sales and the day’s brewed coffee offerings, as well as wholesale accounts’ orders.

Roasting coffee is a simple process but one full of subtlety. A measured amount of green coffee is scooped into the hopper funnel and, once the interior temperature of the roaster is correct, it is released into the drum, where it is rhythmically tossed around over the gas flames to be slowly cooked. The first ten minutes of a big batch are fairly boring as the green coffee absorbs the heat of the drum and then begins to come up to temperature again. Then things get interesting.

These tasks were loud and physical; there was something oddly satisfying about doing this work in front of those who were headed off to sterile cubicles.

Coffee roasting is largely defined by what are known as the two cracks. The first crack is when the water inside the beans starts to boil and expand, causing the beans to split open. This is an audible cue, as thousands of beans begin to crackle and burst. At this point, the temperature must be modulated to keep a steady, controlled pace. After the first crack, the coffee begins to turn from yellow to brown, and as it approaches the second crack, the batch can be terminated if a lighter roast is preferred. As the first beans begin to crackle again, the oils in them are boiling and the beans expand again and run a dark brown as they slowly carbonize. At this point, the beans sustain their high temperature and the flames can be shut off entirely. Now it’s a matter visual inspection using a small sampling cylinder that can be pulled out of the drum. Depending on whether you want a Vienna, French or Italian roast, the coffee can be dumped at any time during the second crack. The end of a roast is dramatic. The front door is opened, the cooling tray arms start spinning and the steaming heap of hot, crackling beans comes spilling out into the tray, smelling like Heaven.

For all the subtlety of roasting beans, there is the sweaty, brutish side as well. The café where I worked was in an old storefront in St. Paul that had trapdoors and a chute for loading supplies into the basement. Whenever a shipment of beans arrived, it was all hands on deck to unload dozens of unwieldy sacks of coffee off of the truck and slide them down the chute into the basement, where two unlucky souls were tasked with stacking them on pallets. Similarly unpleasant was the task of bringing new bags upstairs to replenish the supply near the roaster. Full coffee sacks are 100 pounds of dead weight, not to mention itchy. This was clearly a young man’s job. And then there was chimney sweeping duty.

About once a month the other roaster and I would have to disconnect the exhaust pipe from the ancient Probat and climb a rickety ladder to the roof to clean out the chimney. This was necessary to clean out the carbonized chaff and buildup that gradually shrunk the diameter of the pipe, increasing the risk of fire and decreasing air flow. We could always tell when it was time to clean the chimney: customers at the café complained of the smoke smell inside. We took turns being the man on the roof, while the other person stayed below, both of us playing tug of war with a log rope, on which a sea urchin-like steel brush was tied. It was incredibly dirty work but neither of us wanted to be the one to burn the place down.

As it happens, I never did set fire to the café on my watch. After four years of roasting beans, I finally got my college degree and reckoned it was time to get a “real” job. Soon I was the commuter standing in line for my morning Joe, enviously watching the roaster in the corner. Even now, twenty years on, I have a Proustian response to the smell of roasted coffee through an open car window. And I still check online listings for old Probat roasters for sale. One day maybe I’ll buy one and drop it into a warehouse space, buy a few bags of beans and fire it up.