Physical properties of Sidikalang robusta coffee beans medium roasted from various colors of coffee cherries

Abstract

The purpose of the present study is to investigate the physical properties of medium roasted Sidikalang robusta coffee beans that originated from various colors of coffee cherries. A semi-wet method has been applied for each coffee cherry with a range of fruit ripeness (green, yellow, orange, bright red and dark red). The physical properties measurements include mass loss, mass density, porosity, and water content. After roasted for medium level, the coffee density is difference for each coffee cherries colors namely 0.42 g/cm3 (green cherries), 0.31 g/cm3 (yellow cherries), 0.40 g/cm3 (orange cherries), 0.34 g/cm3 (bright red cherries), and 0.25 g/cm3 (dark red cherries). The mass declined after medium roasted is 16.82% (green cherries), 17.00% (yellow cherries), 18.70% (orange cherries), 18.32% (bright red cherries) and 16.76% (dark red cherries). The coffee beans porosity difference before and after medium roasted is decreases by 13.56% for green cherries and 16% for yellow cherries and increased by 12.22 (orange cherries), 3.44% (bright red cherries), and 6.88% (dark red cherries). Finally, the water content of coffee beans was 8.38% (green cherries), 9% (yellow and orange cherries), 7.91% (bright red cherries), and 10.83% (dark red cherries). The present study concludes that cherries colors have influenced the coffee bean’s physical properties before and after medium roasting.