Effect of steam treatment on the profile of bioactive compounds and antioxidant activity of defective roasted coffee (Coffea canephora)

The article evaluated the influence of steam treatment (ST) on Coffea canephora defective beans regarding the profile of bioactive compounds and the antioxidant activity of roasted coffee. Defective crude beans were treated following a full factorial design 22 with the variables steam pressure (2-8 bar) and process time (3-29 min). The steamed coffees (SC) were dried, medium roasted and grounded. The ST affects (P < 0.05) the contents of caffeine, trigonelline, chlorogenic acids, melanoidins, cafestol and 16-O-methylcafestol. In general, the ST decrease the bioactive compounds and antioxidant activity compared to control sample (without ST). The profile of compounds for the SC roasted coffee depended on both ST and the subsequent roasting process. The bioactive compounds content in roasted SC were higher in conditions that combined a more drastic ST (8 bar/29 min) with a shorter roasting process, or a mild ST (2 bar/3 min) with a longer roasting process. ST with longer times and low pressures should be avoided to prevent the loss of bioactive compounds.