I recently moved from near sea-level (200 foot elevation, I think), to a more extreme elevation in the mountains of Colorado – approximately 8500 foot elevation. Naturally, when unpacking, finding the coffee roaster was a priority, and I eagerly dropped some green beans in to replenish my supply as I was almost out. With the roasting profile I’m accustomed to using, a typical roast would take twelve to fifteen minutes. Since my roaster is in my garage, I decided to work on unpacking boxes while the coffee roasted.
Enjoying the smell of roasting coffee, I set to work organizing the garage. A very, very short time later, I caught a whiff of that not so pleasant smell of smoking coffee beans. I glanced at the roaster and saw a steady stream of thick smoke pouring out the the top vent! I rushed over to stop the roast, but by then it was of course too late (for my tastes, at least). Now, this isn’t the first time I’ve burnt coffee beans, but the amazing thing was that it happened in about SIX MINUTES. I was shocked. That batch was promptly dumped out, and I tried to roast some again, this time never straying more than a few feet during the roasting. The results were similar, and incredibly rapid roast that this time I fortunately caught in time.
I tried roasting a different bean and got the same results. I quickly concluded that it was most likely a factor of altitude, and a Google search confirmed my suspicions. Seems ‘high altitude coffee roasting’ is defined as anything about 3000 feet. My 8500 foot elevation is an extreme example of this! Anyway, here’s what Wikipedia has to say about this subject:
High altitude coffee roasting is a method of roasting coffee at an altitude of 3,000 feet or higher.
In roasting coffee, high altitude allows for quicker roast development at a lower temperature, avoiding the two most common problems of roasting coffee: baking, and scorching. Baking coffee occurs when it is roasted too long, causing inadequate structural expansion and resulting in flavor that is flat and lacks intensity. Scorching coffee occurs when coffee beans are roasted at too high of a temperature causing lack of development and resulting in flavor that is wild and woody. In roasting coffee, heat should be applied at both the lowest temperature possible and for the shortest possible amount of time. High altitude roasting helps accomplish that objective.
I had spent years refining my roasting temperature profiles to get the perfect roast – though my machine couldn’t put out quite enough power, hence the long roast times (I consider 10-12 minutes until the second crack to be ideal, but found I had to push that to 14-15 minutes). Now, I’m back to square one! Time to redo roasting profiles and figure out what is best at these higher elevations. It’ll be a fun process, one that I’ll document here at Coffeeopolis from time to time.