BIOACTIVE COMPOSITION OF COFFEE BLENDED WITH STEAMED PVA COFFEE
Up to 20% of Brazilian coffee production corresponds to defective beans (PVA) which decrease the cup quality of the coffee brew. Steam treatment (ST) could be used to improve the quality of low grade coffees, however it could also affect the content of bioactive compounds on the product. In this research, PVA Coffea canephora beans were steam treated (5 bar for 16 min), dried in vacuum oven, medium roasted and grounded. Good quality Coffea arabica (CA) and Coffea canephora (CC) beans were roasted (standardized by color) and grounded at the same conditions of the steamed coffee (SC). The filtered coffee brews (1:10 coffee:water) were prepared as following: (B1) pure CA; (B2) pure CC; (B3) blend CA:SC (50:50); (B4) blend CC:SC (50:50). Caffeine, trigonelline and 5-caffeoylquinic acid (5-CQA) were analyzed by liquid chromatography and, melanoidins, by spectrophotometry. Lower caffeine content was observed for CA brews (B1: 1.43 mg/mL; B3: 1.63 mg/mL) compared do CC ones (B2: 2.62 mg/mL; B4: 2.12 mg/mL); for this heat stable bioactive the coffee species defined the caffeine content. Similarly, the CA brews had lower content of melanoidins (B1: 11.21 mg/mL; B3: 10.64 mg/mL) compared to CC ones (B2: 14.59 mg/mL; B4: 12.57 mg/mL). Lower content of trigonelline was observed in CC (B2: 0.52 mg/mL; B4: 0.45 mg/mL) compared to the respective CA ones (B1: 0.96 mg/mL; B3: 0.72 mg/mL). The same behavior was found for 5-CQA content (B2: 0.60 mg/mL; B4: 0.55 mg/mL; B1: 0.87 mg/mL; B3: 0.77 mg/mL). The results also showed that SC coffees subject to aggressive treatment (ST and drying in addition to roasting process) presented lower content of the thermolabile bioactives (trigonelline and 5-CQA) and melanoidins. In conclusion, the addition of SC on a blend reduced the content of some components but the coffee species present more influence on the bioactive profile.