Various coffee dryer systems are available, with older models often being converted grain dryers, though these may lack the efficiency of newer horizontal barrel dryers. Modern coffee dryers are specifically designed to enhance efficiency and uniform drying by ensuring thorough mixing of the coffee during the drying process. The primary aim of using mechanical dryers is to accelerate the slowest phase of coffee drying, typically when moisture content ranges from 15% to 11%, thus aiding in preventing fermentation.
In certain high-humidity environments, the entire coffee drying process must occur within mechanical dryers to maintain control over moisture levels. It is crucial, however, to set mechanical dryers at temperatures no higher than 40-45°C. This is a vital consideration when purchasing coffee that has undergone mechanical drying. Elevated temperatures can have detrimental effects, such as killing the germ and compromising the coffee's flavour potential. Additionally, at extreme temperatures, the coffee bean may crystallise. A dramatic illustration of this is that the crystallized bean, when subjected to force like being smashed with a hammer, breaks like glass. Therefore, adherence to appropriate drying temperatures is essential to preserve the quality and flavour profile of the coffee beans.
