Roasting coffee is not so difficult a matter as is often claimed by operators and "experts" who seek thus to magnify their importance; but it is nevertheless a process about which a great deal may be learned in the school of practical experience. With one of our modern machines anybody with ordinary intelligence and nerve can take off a roast after one trial which would pass muster in many establishments, but that same person applying himself to the roasting job for a week will either be turning out vastly better roasts or will have demonstrated that he never can excel as a roasterman.
Modern coffee roasting machines provide for easy control of the heat (from coal, coke, or gas fuel), for constantly mixing the coffee in such a manner that the heat is transmitted uniformly to the entire batch, for carrying away all steam and smoke rapidly, for easy testing of the progress of the roast, and for immediate discharge when desired. The operator's problem therefore is the regulation of the heat and deciding just when the desired roasting has been accomplished.
If all coffees were alike, roasting would soon be almost automatic. In some plants most of the work is on one uniform grade or blend. But coffees which vary greatly in moisture-content, in flinty or spongy nature, and in various other characteristics, will puzzle the operator until he establishes a personal acquaintance with them in various combinations in repeated roasting operations. The roasterman therefore must be able to observe closely, to draw sensible conclusions, and to remember what he learns. Roasting coffee is work of a sort which anybody can do, which a few people can do really well, and no one so well but that further improvement is possible.
There is no absolute standard of what the best roasting results are. Some dealers want the coffee beans swelled up to the bursting point, while others would object to so showy a development. Some care nothing at all about appearance as compared with cup value, while others insist on a bright style even at some sacrifice of quality. Business judgment must decide what goods can be sold most profitably.
The loss of coffee in weight in the roasting operation, or shrinkage as it is called, is a matter which offers opportunities for false claims of advantage in roasting processes. Anybody can see that if just as good roasted coffee could be produced with a lessened shrinkage there would be a chance for a decided increase in profits. It is a sort of finding-money proposition which always turns out to be too good to be true. The purpose of roasting coffee is to produce an article entirely different from green coffee, which is accomplished mainly by driving out moisture. If coffee is roasted thoroughly, inside as well as outside, so as to give the greatest roasted coffee value, it must sustain a proper loss in weight which there is no legitimate way to avoid. The amount of shrinkage varies a great deal with the kind of coffee and its age, also with the kind of roasting desired.
Adding a little water to the coffee at the end of the operation has the advantage of checking the roast at the desired point and helping to swell and brighten the coffee, but it is a practice which is sometimes abused by soaking the coffee with water so as to reduce the shrinkage. This is done either dishonestly, to steal coffee which belongs to somebody else, or foolishly; for the heavier coffee has a lessened cup value which more than counterbalances the apparent gain.
A Typical Coal Roaster
A typical United States coal roaster is shown in the accompanying cut. It is the latest form of that type of Burns machine which requires a brickwork setting. The picture shows the roaster ready to operate, except for smoke pipe and power connections.
