Exploring the effects of roast profiles and grind size on extraction dynamics and volatile fingerprinting in Indian coffee varieties

The extraction process is crucial for optimal coffee quality but remains understudied for various Indian coffee types. This study examines extraction dynamics in Indian Arabica Cherry, Indian Arabica Parchment, Indian Robusta Cherry, Indian Robusta Parchment, and Monsooned Malabar by varying roast profiles, grind sizes, and bean densities. Using a controlled pour-over method (coffee-to-water ratio of 1:17 at 92 °C), we measured Total Dissolved Solids (TDS) and extraction yield across light, medium, and dark roasts and coarse, medium, and fine grinds. Light and medium roasts yielded moderate extraction percentages (19-21%), while dark roasts showed a broader range (17.8% to over 23%). Monsooned Malabar's unique processing led to distinct extraction behavior due to altered bulk density and moisture content. Statistical analysis confirmed significant effects of roast profile and grind size on extraction efficiency, affecting TDS levels and overall yield. Volatile compounds were characterized using an electronic nose (e-nose) system, with heat maps showing distinct extraction patterns and bar charts illustrating volatile profiles.