Before the advent of drum roasters, it was the common practise to roast coffee in uncovered earthenware tart dishes, old pudding pans, and fry pans in the home over charcoal fires without a flame.

In about 1400 AD, shallow iron dippers with long handles and foot-rests designed to stand in open fires, were used in Baghdad, and by Arabs in Mesopotamia, for roasting coffee.

Pan Roasting

This method involves roasting coffee beans in a shallow pan over an open flame. It’s one of the simplest and most ancient methods of roasting. The beans are constantly agitated to prevent uneven roasting and burning. Pan roasting requires careful attention to colour changes and aroma development, making it a sensory-intensive process.

Drum Roasting

Drum roasting involves placing green coffee beans in a rotating drum over a heat source. The rotation ensures even heat distribution, leading to consistent roasting. This method is reminiscent of traditional methods used in many cultures, where large drums or cylindrical containers were used to roast beans over an open fire.

German Coffee Machinery

The Germans first began to show an active interest in coffee machinery in 1860. In that year, Alexius Van Gulpen, of Emmerich, produced a green-coffee grader; and later (1868), in partnership with J. H. Lensing and Theodore von Gimborn, began the manufacture of coffee-roasting machines. From this start there developed in Emmerich an industry in coffee- machinery building. In 1870, Alexius Van Gulpen introduced to the German trade a globular coffee roaster employing wood and coke as fuel and having perforations and an exhaust.

Van Gulpen and von Gimborn are the two names most often met with in the development of German coffee- roasting machine

Reference: All About Coffee by William H. UKERS