Evaluation of far infrared technology in coffee roasting for improved heat dynamics energy efficiency and sensory assessment

Abstract

The rotating drum roasting method is currently among the most prevalent roasting systems used throughout the industry. The drum operates with heat conduction that develops when coffee beans touch heated metal surfaces while relying on heat convection for circulating hot air across the surface of the beans during roasting. However, no research has yet applied the use of irradiation in roasting machines. This research investigates the heat radiation of far-infrared heaters in a roasting machine by installing the FIR heaters in the center of the roasting drum. The electrical power of the FIR heaters is set at 5 levels, namely 1,000—3,000 watts per step, increasing by 500 watts respectively. The results showed that the coffee beans are exposed to greater heat and roast faster as the power emitter is increased. During coffee roasting, radiative heat impacts the process to a greater extent than convective heat does. Surface area influences how effectively they operate because larger areas transfer heat more efficiently. The roasting process takes a shorter time when performed on surfaces that have high emissivity, but beans with reduced surface exposure need longer roasting periods. This research can be utilized to identify suitable conditions in the roasting process by employing a combination of irradiation techniques and heat conduction in the roasting machine.