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Man or Machine:
Who’s the Better Roastmaster?

BY TIMOTHY J. CASTLE

Technological improvements Technological improvements in coffee roasting have followed two basic but very different philosophies over the past several years. The first approach to technological advance in coffee roasting attempts to eliminate the “human factor” with automated control systems of varying sophistication. The second approach attempts to assist the human operator in better control of the roasting process with increasingly sophisticated systems of measurement (including temperature, moisture, humidity, air pressure, etc.) and roasting parameter control (time, temperature, method of heat application and airflow).

Obviously, the first approach cannot be achieved without bringing to bear all the tools required by the second approach. The difference, in the end, is that in the first case a predetermined set of parameters is established which cue off measurements collected during the roasting process. A control process unit, a rudimentary computer, essentially, controls the roast. In the second approach, the control process unit is a human operator who also adjusts roast parameters according to collected data but has more flexibility to fine-tuning a specific roast according to variables, often very nuanced, that occur during a particular roast.

The argument for the first system is that a computer will always be more consistent than a human operator. Those arguing to keep the human roaster employed say that an experienced roastmaster can always achieve a better result because no two lots of coffee are the same, that coffee changes every day, and the roasting environment does as well, from day to day and hour to hour. Some changes in the roasting environment are still too subtle for computers and today’s measurement systems to detect - nothing can replace a dedicated, passionate roaster who is deeply concerned about the final result. That person will bring all their senses and experience to bear to bring out the best in each roast while still hewing to the company’s preferred roast stile.

Where proponents have room to co-exist is pretty much the same way the proponents and detractors of super-automatic espresso machines have learned to live together - if the human operator is competent enough, and dedicated enough to their work and the result, then they can probably out-roast an automated roasting system. The problem is, both camps agree, that there aren’t enough people out there who are capable and desirous of doing the job.

At least both sides claim to agree. The fact is, at some point in a roasting company’s growth, it becomes very difficult to keep the craft approach. By increments, systems become more automated and gradually, for financial reasons, the human operator is eliminated. In addition to losing their roastmaster, companies at this point also often lose the only person (the roastmaster) who could have helped them adjust and perfect as much as possible, the right automated roast profiles. Quality suffers, of course, but again, the person that would know (again, the roastmaster) has already been shown the door.

To whichever end the technology is being applied, much of it is being developed for existing roasting installations rather than for new equipment. Much of the currently available new equipment, though, is continually being upgraded in the ability to measure and control the parameters of the roasting process.

Also complicating things are those “craft” roasters who don’t believe that any technological advancements are necessary and that all that’s needed for a good roast is a zealously dedicated roastmaster with a good sense of smell, hearing, sight and taste and, of course, a good piece of roasting equipment, preferably of German manufacture and of a 1920’s vintage.

Read on for comments on this most vital issue from some leading coffee roasting experts.

Stephan Diedrich, owner, Diedrich
Coffee Roasters; Sandpoint, Idaho:

“We’ve been getting much more heavily involved in the automation technology and the automatic roast control systems. And with that we have quite a few new things, whether they be small in-store roasters up to the industrial roasting systems. So in automation, there’s quite a bit new that’s there. In roasting technology there is a lot that can be done even with existing roasting technology and really refining it and improving the quality that is produced by any machine - and that is a matter of training people. But with the automated roast control systems that we design, we have different variables that are really based on the versatility that you have with the Diedrich roasters. Most of the other roasters on the market, only have a small fraction of the variables that can be controlled on a Diedrich roaster.

The automation control systems are designed around the controllability that you have with the Diedrich coffee roasters but we’re adapting or retrofitting other machines on the market with the automated roast control systems. The variables we control on the Diedrich roaster are air temperatures, bean temperatures, air flow velocity and time. We can achieve very exact degrees of roast and with the control systems, we’re monitoring or using 15-second check points for all four of those variables. On the big roasting systems we’re getting much more involved in the commercial roasting systems, the industrial roasting systems, the 45 kilo through four bag roasting machines and that is the essence of what we are doing in new areas at this point.”



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