Innovative baking technology in the 20th century: the baking method using purely hot air flow

Surely, how could there not be innovative baking technology in this era of the twentieth century? In the mid-20th century, two major milestones in the evolution of baking technology from direct and indirect fire to hot air.

In 1934, the Gabe Burns Company developed a prototype of the Thermalo bean dryer, which applied little heat to the walls of the roasting drum, leaving a strong heat to roar through the roasting chamber as the main heating medium. This arrangement allows us to roast coffee beans at a lower air temperature because the fast-moving air carries away the gases produced during roasting and improves the efficiency with which coffee beans are heated. Advocates of the innovative technology have this line of reasoning: "The lower air temperature combined with the relatively fast moving gases burns less flavor oil, so the beans roasted with this technology have better aroma performance."

In addition, in the 1930s, there was a completely abandoned roasting drum structure, but still retain a strong hot air flow while roasting and stirring coffee beans first appeared, this type of air-flow type of bean dryer works in a way very similar to today's domestic hot air popcorn machine: hot air flow can also make coffee beans tumbling and roasting purposes. The term "airstream" comes from the fact that coffee beans churn inside the roasting chamber as if they were a fluid when this type of dryer works. The principle of the air-flow dryer is similar to that of Gabes Burns 'Thermalo: the accelerated flow of hot air makes the baking temperature relatively low, and the batch baking time is shorter. In theory, this method of baking takes less flavor fat.

In the United States today, the most widely used design of an air-flow bean dryer is that developed by Michael Sivetz, a technician and author who has had a profound impact on the American coffee industry. The air-flow dryer developed by Mr. Sivitz works on the principle that a strong hot air flow from below blows upward, and the coffee beans are blown up along the vertical wall of the roasting chamber, and then fall down like a waterfall. In this way, they are continuously stirred to achieve uniform roasting. You can see a picture of one of the Sivitz bean dryers and related instructions on page 55 of this book.

Over the past 50 years, many other airflow roasters of different designs have been developed and gradually become popular on the market, some of which are only a slight change from the patented design of 50 years ago (the design in which the hot air blowing from the bottom of the roasting chamber into the roasting chamber blows the coffee beans upward and finally falls naturally along the walls of the roasting chamber). Others, such as the Roller Roaster designed by Australian Ian Burstein and the System 90 Centrifugal, Packed-bed Roaster by Gabes Burns, are excellent baking collimators that take their line baking concept to heart. There are also some models that show the "airflow roasting process" as a gimmick. You can see the coffee beans tumbling upward in the glass roasting room, which can attract customers 'attention and make them interested in understanding the relationship between roasting technology and taste. These new small shops use airflow roasting machines to simplify the construction of the bean dryer, and the operation process is also automated as much as possible.