_ Several months before I started dreaming of getting into the coffee business I learned that there was a manufacturer of roasting equipment located in Corvallis, OR. Intrigued, I searched for it online and discovered the crude web page of aging coffee guru Michael Sivetz. A bit of research revealed Sivetz to be an intriguing and accomplished character who rigorously devoted his career to coffee science and invention.
When time came that I was interested in buying a roaster, Sivetz' machines were high on my list of ones to consider. I visited the shop and was helped by Diane (the sole employee) while the 90-year-old Sivetz hunkered around the corner with a newspaper and a cup of coffee. Diane was kind enough to introduce me. “HEY MIKE,” she yelled. “THIS...IS...JOSEPH. HE'S INTERESTED IN A ONE-POUND ROASTER.” Sivetz nodded with some unknown degree of interest or understanding.
Later when I actually purchased my roaster, Mike methodically walked me through the basics of operating his machine, while Diane (with caution and amusement) observed for signs of dementia and accidental misinformation.
When I called the shop last week to order some replacement parts, Diane informed me that Mike had passed away in March. A nice article was written in his memory here.
Mike Sivetz' major contribution to the coffee world was the invention of the “fluid bed” or “fluidized bed” air roaster, the name of which refers to how hot air levitates and circulates the beans such that the beans are said to behave like a fluid. Sivetz was passionately opinionated about the superiority of fluid bed roasting over traditional drum roasting, as seen in this article.
In my brief experience with Mike and in my reading of his work, I view his legacy primarily in terms of the promotion of science over art in the world of coffee.
The notion of “roasting as art” pervades the coffee industry. Stumptown Coffee Roaters draws on metaphors of music, architecture, and karate to lead into this excessively romantic statement on their website: “Coffee roasting consists of a balance of right-handed timing and intuition; it is an art that flows through the rigidity of time and temperature, but yields to the organic nature of craft.”
Closer to home, Ticos Coffee in Stayton employs the common term “artisan roastery” and goes on to say that they are “totally captivated by the art of roasting.” The French Press website says, “Some call it science, others call it art; we like to think of roasting as a little bit of both.”And in a Statesman Journal feature on Alyssa (Governor's Cup owner), she says this of roasting: “There’s a science to it, and a gut instinct, artistic part as well.”
I am completely enchanted by the notion of artistry in roasting, but as I actually entered the trade I started to have doubts about its authenticity. Were roasters co-opting the term “art” to sugar-coat inadequacies of knowledge and scientific understanding? Or was the coffee industry simply promoting the romantic notion of artisan roasting to market their product?
In this atmosphere, Mike Sivetz' completely unromantic treatises on coffee roasting were quick to engage my attention. He believed that the important elements of coffee roasting and resulting flavor were quantifiable, measurable, and with the right equipment (his own) reproducible. One of the significant features of his fluid-bed machines is the accuracy with which one can measure bean temperature, which Sivetz relates directly to roast profile and taste. I remember that when he was demonstrating to me how to use his roaster I asked about changing the settings to get different roast levels and he replied somewhat gruffly that there was no reason to roast outside of a very narrow range: it was as if he was unwilling to admit even that taste perceptions and preference could vary outside of his scientifically prescribed ideal.
Sivetz' fluid-bed air roasters are badly suited for artisan hype. They are more fully mechanized than most drum roasters. The roaster pays more attention to bean temperature than to the sight, sound, and smell of the beans. But the fundamental principle is the same with both methods: heat the beans up until they are roasted, then cool them down.
The debate over “drum-roasted” coffee versus “air roasted” can be mind-numbing if one delves too far into it. I didn't enter the coffee business with any preconceived preference but selected a Sivetz air roaster after a lot of deliberation with a major factor ultimately being the ease of going down to Corvallis and buying it in person. Both roasting methods certainly have a place in the industry.
To put things in a local perspective, the Governor's Cup (a fine establishment) uses a German-made drum roaster, as does Stumptown Coffee Roasters. The green coffee beans sit inside a metal drum which rotates as heat is applied underneath it. Air heats the metal drum and the metal drum in turn heats the beans (conduction heating). In fluid-bed air roasters the beans are heated directly by hot air (convection heating). In roasting it is imperative that the beans constantly move; therefore in air roasting it is the strong, focused hot-air currents that move the beans (see my roasting video), whereas the rotation of the drum is what achieves this goal in a traditional roaster.
There are some clearly identifiable advantages to both methods. In air-roaster's favor, it is more efficient to heat the beans directly rather than heating a metal surface to conduct heat to the bean. Also, since there are no moving parts in air roasting (other than the air itself), it is easier to accurately gauge the actual bean temperature by inserting a thermocouple into the roasting chamber. Furthermore, since the beans are completely immersed in the hot air, they achieve a more even roast. An advantage of drum roasting is that the operator has more control over the process: including the input of heat, air flow and humidity control. Of course, the operator must have adequate skill (or artistic ability???) to judge all these controls well, and inadequacy will surely lead to poorer coffee.
More subjectively, some people prefer the cleaner taste derived from air roasting. They say that heating beans via conduction on the surface of a drum creates harsh, scorched flavors; they also note that the chaff of the coffee remains in the drum, generating more smoke, whereas air roasters have the advantage of blowing off the chaff. Others, however, believe that drum roasting creates more complex flavors and that the less efficient (slower) heat transfer allows for fuller flavor development. Generally speaking, it is frequently said that drum roasting has a positive effect on coffee's body (creating a fuller mouth-feel) whereas air roasting improves a coffee's acidity (creating clean, bright flavor tones).
Mike Sivetz considered drum roasting to be an antiquated method. He blamed the failure of air-roasting to take over the industry on consumers' rigid taste preferences, which were developed in an era of drum-roasted coffee. He wrote, “One can only expect a newer method and product to take some years to replace a traditional one.”
Sivetz probably underestimated the value of tradition, beauty, and craft in roasting. Just one look at the architecture of a German Probat Roaster is enough to activate the senses and inspire an innate urge to sit with a steaming cup of coffee and pen poetry. Yet I am convinced that the romantic notion of artisan roasting is overstated. Even with a beautiful, manually operated machine, the roaster makes decisions that lead to scientifically observable results. Using sight, sound, and smell to determine when a roast is at the perfect point is not on par with Mozart composing a symphony. And if it were, then we would have to admit to the subjectivity of art and use a discerning palette to critique the artisan roasters work.
There is a beauty and romance steeped in the nature of coffee, which I hope not to degrade. But Steel Bridge Coffee represents a blending of pragmatism into that total picture, for which I am indebted to Mike Sivetz—a man whose legacy is alive and well.