is one of the earliest industrial devices for roasting such foodstuffs as coffee, cacao, cereal, chicory, malt, and nuts. Roasted malts and grains, when used in the mash, can impart color and roasted flavors to beer. Roasted malt flavor and color are integral to a number of beer styles, especially porters and stouts. Depending on the technique employed, ball roasters can also be used to produce caramelized malts.

Developed in the mid-19th century, the ball roaster’s roasting chamber was an enclosed, rotating, ball-shaped iron container. It replaced the traditional flat, open pan, which was the common roasting equipment in the more distant past. Roasting pans tended to yield uneven results, because some seeds or beans invariably ended up being only partially roasted, while others were lightly to severely scorched. Such over-roasted foods were too acrid to taste pleasant. The ball roaster, on the other hand, needed to be hand-cranked on an axle above its heat source of charcoal, coke, or coal. This caused the contents inside to tumble constantly. The roasting process, therefore, was slow, even, and controllable. Used with skill, the ball roaster could deliver roasted and caramelized malts of consistent quality with exactly the flavor and aroma characteristics desired. The basic technology of the ball roaster has changed little since those early days, except for the cranking power, the heat source, and the capacity. The hand crank is a thing of the past, and the preferred heat source nowadays is gas.

The first patented rapid gas roaster was produced in Germany in 1899. While early roasters had a capacity of perhaps 5 kilograms (approximately 12 pounds), they eventually grew to sizes that could roast hundreds of pounds of malt per batch. In the United States, these roasters were known as “K-balls,” the “K” standing for “kugel,” the German word for “ball” or “sphere.” Some were used in the US malting industry well into the 1990s, but these days the ball roaster is largely used for roasting small-batch coffees. The roasting machines in modern malting plants today are computer- controlled, cylindrical drums that can produce up to 3.5 tons of roasted malt, caramel malt, or roasted barley per batch.

See also drum roaster, roasted malts.