Effect of reversed coffee grinding and roasting process on physicochemical properties including volatile compound profiles

The conventional coffee roasting process includes roasting, grinding and extraction. Current study developed reversed coffee roasting process: grinding first before proceeding onto the roasting process. The physicochemical properties and volatile compound analysis were conducted on coffee prepared with conventional and reversed coffee roasting process. Two coffee samples, including coffee powder roasted with conventional process (C, control), and coffee powder prepared by reversed method of grinding and roasting (R. reversed). The L* value of commercial coffee was used as an index of roasting time and temperature. The particle size of R was significantly lower than that of C (p < 0.05) by 21.0%, respectively. The amount of trigonelline in C (264.23 μg/g) was significantly lower than R (p < 0.05). Other characteristics including L* value, moisture content, and pHs were not significant different between two coffee samples (p > 0.05). The volatile flavor compound profiles of two samples were slightly different, indicating potential flavor differences. Industrial relevance This study demonstrated new coffee roasting process, which is different from conventional coffee roasting process. Finding from current study suggest using the reversed coffee roasting process for commercial usage in coffee roasting process.