An “espresso profile” is not necessarily darker: the roasters interviewed by Perfect Daily Grind in 2019 often keep the same temperature and the same time after first crack but lengthen the Maillard phase and the development to make the bean more brittle and more soluble, extraction under pressure lasting 20 to 30 seconds; filter calls for shorter, more dynamic profiles that preserve acidity and origin aromas.

A darker roast is more porous, therefore more soluble, with more melanoidins for body and crema stability, and fewer acids. The residual CO2, which hinders espresso, matters little in filter, except through the bloom (see the cup).

Perfect Daily Grind, 07/08/2019 (Brian Webb, Lukasz Jura, Trey Cobb); Gagné 2021, p. 159

Decaf is roasted differently. Decaffeination by solvent (beans moistened to over 30% water, solvent at 40-70 °C, steam, drying), by supercritical CO2 (above 31 °C, its critical temperature, the training document giving 30.6 °C, under very high pressure, gas washed with water and recycled, costly but judged the best in taste) or by water (baths saturated with coffee compounds except caffeine, up to ten passes, 0.01 to 0.02% residual caffeine, with transfer of some of the precursors to the water, which the activated carbon filters of the Mexican and Canadian processes try to limit) leaves a green bean that is darker, matte, less moist and more porous, which absorbs heat faster, browns well before first crack and cracks almost silently.

Swiss Water (December 2025, with the trainer Rob Hoos) advises a gentle, progressive start, a prolonged development with a steady decrease in gas, and “feeling” first crack rather than hearing it; Sweet Maria's warns that a decaf is not judged by color. See caffeine.

Professional training document, caffeine and decaffeination processes, pp. 2-3; Swiss Water, Optimizing the roast of decaffeinated coffee, 12/23/2025; Sweet Maria's, Roasting decaf coffee (accessed 09/07/2026); Gagné 2021, p. 160; NIST Chemistry WebBook, carbon dioxide, critical point at 304.13 K