The effects of temperature and roasting time on the quality of ground Robusta coffee (Coffea rabusta) using Gene Café roaster

Abstract

This research aimed to determine the effect of temperature and time of roasting by using the Gene Cafe’ roaster on the quality of Robusta coffee and determine the appropriate treatment to obtain the best ground coffee. The method used in this research was the experimental Completely Randomized Block (CRB) using 2 factors, which were roasting temperature (225°C and 250°C) and roasting times (10 minutes; 15 minutes and 20 minutes). The parameters observed were chemical quality characteristics (moisture content, ash content, caffeine content), physical characteristics (moisture content, ash content, caffeine content and antioxidant activity), physical quality characteristics (yield, colour and browning index) and organoleptic quality(aroma and taste). Data were analyzed with analysis of variance (ANOVA) at 5%significance level by using software Co-Stat and a significant difference data were tested further by real difference test with Honestly Significant Difference (HSD) test. The results showed that the interaction between temperature and roasting time give significant effect on all parameters, such as moisture content, ash content, caffeine content, antioxidant activity, yield, L* value and °Hue of colour value, browning index, aroma (hedonic and scoring) and taste (hedonic and scoring). The treatment of roasting temperature at 225°C and roasting time for 20 minutes was the best treatment to produce ground Robusta coffee with moisture content 2.63%; ash content 4.66%; caffeine content 2.17%; antioxidant activity 50.93%; yield 73.33%; brown ground Robusta coffee (°Hue value = 16.75 and L* value = 13.93), browning index value 232.89; aroma (strong and slightly like) and taste (bitter and slightly like).