Mr. Jabez Burns was an extraordinary engineer who patented the prototype of modern coffee roasters in 1864. In 1929, our Jabez Burns Number 7 Roaster was built in New York City by the Burns Company, which is still manufacturing quality coffee roasting equipment today. The Kaffeeklatsch installed this roasting plant in 1977, introducing our neighbors to the aroma of freshly roasted coffee beans.
The maximum capacity of this machine is 30 kilograms (66 pounds) or a “half bag” of green coffee. An electric motor turns both the roasting and cooling drums, while a natural gas burner roasts the beans at 400–450 degrees Fahrenheit. Our roastmaster, Grant Heath, weighs the green, raw coffee beans and loads them into the top cylinder where they are tumbled over the flames. When done, the coffee is dropped into the bottom cylinder for air cooling. Because the coffee is roasted in small amounts or “batches, the process is called “batch roasting”.
Roasting coffee by this method is call “sight roasting”, and it is multi-sensory work. The roastmaster uses all of his senses to make sure the coffee is roasted perfectly. He constantly checks for the proper color and aroma and also must listen for the popping sound made as the beans approach the desired roast.
Roasting causes both physical and chemical changes in the coffee beans. Coffee beans change to a darker color as the sugars caramelize with the increasing heat of the roast. They also double in size yet decrease in weight by 16-20 %. In the final stages of roasting, the fully developed beans release the aromatics of freshly roasted coffee.