<![CDATA[ABSTRACTCoffee roasting is an essential stage in coffee processing because it significantly influences the physical properties and overall quality of roasted beans. In drum roasting systems, the rotational speed of the drum affects bean movement and heat transfer, thereby influencing roasting uniformity. This study investigates the influence of drum rotational speed on color uniformity, examines the effect of roasting duration on moisture content, and identifies suitable combinations of roasting time and rotational speed. An experimental approach using a 3×3 full factorial design was conducted with a drum roasting machine powered by a 25-watt DC motor. The experimental variables consisted of roasting durations of 60, 90, and 120 minutes and drum speeds of 10, 20, and 30 RPM. Color uniformity was assessed through digital image processing using grayscale analysis, while moisture content was measured through laboratory proximate analysis based on the AOAC method. The findings indicate that the influence of drum speed on color uniformity varied according to roasting duration. The highest uniformity for light roast was recorded at 60 minutes and 10 RPM, reaching 57.57%. For medium roast, the maximum value of 54.40% was achieved at 90 minutes and 20 RPM. Meanwhile, dark roast obtained its highest uniformity of 56.43% at 120 minutes and 10 RPM. The lowest uniformity, 45.19%, occurred at 120 minutes and 30 RPM. Moisture content generally declined as roasting time increased, ranging from 0.2984% to 1.9432%. All samples remained below the 5% maximum moisture limit specified by SNI 01-3542-2004. Based on the results, the recommended operating conditions were 60 minutes at 10 RPM for light roast and 90 minutes at 20 RPM for medium roast.Keywords: coffee roasting, drum rotational speed, DC motor, color uniformity, moisture content.]]>
