Evaluation of Fluidized-Bed and Drum Roaster Performance in Roasting of Robusta Green Bean

The roasting process is essential in producing ground coffee as it is where coffee's distinctive aroma and flavour are developed. There are two coffee roasters: drum and fluidized bed roasters, each with benefits and drawbacks. This study aimed to determine the effects of roasting machine type and roasting level on the characteristics of Robusta coffee. The experimental design used was a 2x3 factorial of a Randomized Block Design. The results indicated that the water content, ash content, caffeine content, total phenol content, bulk density, colour, coffee ground aroma, brewing colour, brewing aroma, bitterness, acidity, and sweetness were all affected by roasting level. The interaction between roaster type and roasting level affected the water content, total phenol content, bulk density, colour, ground coffee aroma, brewing aroma, bitterness, and acidity. The analysis of volatile compounds in ground roasted coffee by hot-air and drum roasters at light, medium, and dark levels revealed 40, 20, 18 and, 46, 48, 48 volatile compounds, respectively. As a conclusion it was found that the type of roasting machine and the degree of roasting have a strong influence on different characteristics of coffee powder, including moisture content, ash content, total phenol content, volatile compounds, bulk density, colour, and sensory qualities like aroma, bitterness, acidity, and sweetness. However, they didn't have a significant impact on the caffeine content.